Monday, December 3, 2012

New Idea for Tune-able board

Hi All. 

Well I’ve been offline for quite a while now. I’ve had some family sadness going on that took a great deal of joy out of most things. I have to say that I became very aware of the therapeutic power of being out in the ocean, cruising around and just taking in the majesty of it all. So as life moves on towards its different normal I’ve found myself thinking about a new board and stumbled on an idea that I’m really excited about.

I had a bit of an ah ha moment when I was thinking about how flexible my light wind board is and how that is limiting its pop-ability – build a external plate to screw to the the middle to stiffen it. Then I realised this idea could have some other very cool applications.

Here’s the idea. Continue to build the simple flexible cores that I have in the current light wind board but add, say, 4-6 additional inserts distributed around the middle and along the centre line. Plates with different amounts of concave, stiffness and rocker could be bolted on to the mid section to affect those same things in the board. For example, if the core has 0mm concave then lateral ribs with any amount of concave you wanted could be built and screwed to the mid section on the top of the board. You could even put them where the handle inserts go. Make them stiff enough to pull the concave into the board and there you have it. Instant concave!

The same would apply to plates that could stiffen the mid section, or add/ flatten the mid section rocker.
The tuning plates extended to near the edges of the mid section you could also use the plate as a place to secure hard wearing c-section material over the rails of the board so that you could ride over things like pvc-pipe rails and jumps. If these edge protectors were thick enough on the underside of the board, they could act like a channel and help when riding fin-less.

So the two key uses for this:

i)                    Prototyping: for DIY’ers tweaking the concave, rocker and stiffness means building a new board for each configuration. However, getting the right amount of each is as much art as it is artJ. Tunings plates could be built to quickly and very cheaply vary these parameters so that you could properly test out what they do and what you like.  For stiffness you could build up the plate by successively adding more and more thin plates of the same shape. It might also be possible to incorporate a some kind of tensioning device like a spring that you could tension up and down with a screwdriver so that you could continually vary it.

ii)                   Once you’ve got a ‘quiver’ of tuning plates you could then swap them around on any given day – wake style in the morning, flexible board for riding chop, dead flat board for light wind or free-styling......big concave board just to see what the hell it does!!

In theory it seems that it might be possible to tune the one core to be specific for different styles instead of having one board that trades off style-specific features to make it more general purpose.

Even better than all of this is you could serious bling up the tuning plates: the outline of them, what they’re made of ( aluminium I-Beams, hard-woods, plastic) you could even make it furry if that was your thing!

A construction issue that will take some thinking about is how to reinforce the inserts to protect them from the lateral forces they’ll be subjected to. At the moment the forces are largely all perpendicular to the board. The lateral forces may well loosen the inserts unless the forces are distributed over a larger area. Maybe with base plates or connecting stripes over the bottom of the inserts.

I’m very excited about this idea. I’ll post more as the idea evolves.

Friday, October 12, 2012

More CNC friendly Board-Off

During the week I replaced the macros for exporting the board outlines as DXF files which hopefully mean that the outline generated in BoardOff can be used by CAD/CAM software without any modification to drive a CNC machine.

It turned out to be easier than I thought. I just created a basic DXF drawing in ACAD9 with the types of lines, curves I wanted to added. This gave be the nasty, in coherent header and a proforma for each of the curve types I needed. A bit of cutting and pasting to turn it into VB and ta daaa

 Previously the outline was made up of 1mm, seperate line segments. When I tried to load it into Mach3 (Shareware CAD/CAM software) it didn't create a tool path correctly. With the upgrade I've changes to a new type of DXF entity called a polyline which is a single line made up of a long list of coordinates - much like G-Code which is the language of CNC control.

 LazyCAM, which is the tool I used for creating the G-Code to import into Mach3,appeared to create a sensible tool path and didn't miss anything. Yet to be tested on a CNC but I'm hopeful that the output from BoardOff can be loaded into a CAM package without modification.

 So far, I've only upgraded the outline template. The plan is to do a bit of work on the rocker jigs and explore whether its possible to generate a 3-D surface for the rocker table. From what I've read you can take a grid of 3D points and create a topological path to pass a smooth surface through them - which sounds like a 3D spline fit. It might be possible with BoardOff to pull out the vertices for 1mm x 1mm tiles (a POLYMESH in DXF speak) and use that. Not sure how smooth the surface would be though. Maybe enough if your willing to clean it up a bit before using it.

  Screen Capture BoardOff output in LazyCAM

Wednesday, September 12, 2012

Controller Working!!!

After months of this project being a work in progress, the pressure and temperature controller finally got completed today and....... wait for it... it damn well worked!!!!

I'll be able control the vac pump without the need for a manual regulator and heat blankets including creating safe ramp-up profiles and log all the data for future reference.

Check out some more photos on the forum under 'Equipment Projects'

Monday, September 10, 2012

Heat blanket stage 1

Yesterday I had a chance to pour the main area of the heat blanket. I cured it with out any pressure on it and so unfortunately it picks up a few wrinkles from the protective plastic I laid down on the work surface. However, it only has 660gm of rubber in it so I have some left over to try to remedy it.

Check out all the details on the Equipment Forum here. Construction details

Saturday, September 8, 2012

Heat blanket under way

 I've gathered all the bits I need for the heat blanket and will start making it in a couple of days. I've uploaded photos and discussions on the forum. Check it out here >>Heat blanket kick off

Thursday, September 6, 2012

First project to find a home here - Thanks Mikelli

We have our first project to hit the forum - a board close to my heart - a light wind machine!! Thanks for jumping on board Mikelli and we're looking forward to watching your progress.

Check out Mikelli's 'Door' and see what you think!

Tuesday, September 4, 2012

New forum on site - BETA

With approaching 100,000 visits there are clearly loads of other kiteboard projects out there that are not getting the publicity they deserve so I thought it would good to add a forum to the site so that people can use the site to more easily share their projects and knowledge and generally show off their pride and joys.

You'll see in the pages listed over on the right hand side the new Forum page.

  Forum Page

Because the forum is hosted elsewhere (Nabble) you'll need to register for the forum even if you all ready subscribe to the blog.

So please jump and register on the forum and start a new topic in which ever forum makes sense and lets start building an more interactive community. Please pass the word around to anyone looking for a project home-away-from-home for the board building projects.

Monday, September 3, 2012

Silicone heat blanket

After running the numbers I realised that I wasn't going to be able to run the 200C blanket from domestics mains supply so a change of plan. I'm going to make 1 kW blankets that should be enough to reach 100C which should cover of all the epoxy curing needs. The dye sub heater will have to go on the back burner for a while.

So here the revised numbers for the blanket

150 x 50 cm usable area. 6 separate circuits in parallel each with 6 lengths of wire in it. I bought some 32 gauge wire (0.2mm dia) on ebay from the US which has 34.68 ohms/m resistance for about $4 for 10m.  I've ordered 2 kg of Mold Max 40 from in South Australia for around $50/kg. This is a condensation curing ( tin catalyst as opposed to platinum) 2 part silicone rubber that has a max temp rating of 205C which is more than enough for the spec'd down blankets.

I had originally order Mold Max 60 which is rated to 293C but changed that after running the numbers on the hotter blanket. BTW the 40 and 60 refer to the hardness of the cured rubber on the Shore A hardness scale. 40A hardness is about the hardness of a pencil eraser, 80 is the hardness of a car tyre so 60 is in the middle.

On is seem that the blankets are coming in under 3mm or so. There are typically 2 layers of fibreglass with the resistance wire in between. This gives electrical insulation and makes for a strong finished product.

At the lower temperature of 100C it should be ok to solder the resistance wire to a mains input wires. I believe that solder typically melts at around 170C or so. The best idea on seems to be crimping the resistance wire into aluminium tubes and soldering the tubes onto a bus bar of some sort. Still seeing if there is an easier way to do this and make sure the wires remain well insulated from each other.

Tuesday, August 28, 2012

Dean Delivers

Check out the Shinai board that Dean built! Bamboo and Paulownia with home made fins!!Looks awesome.

The outline was based on the 'B8 WakeUp' design created in BoardOff. The plans are available in the Board   Project Plans on this blog. Deans doing a great job of documenting his projects and trying some innovative things in construction process.

Heater blanket project

I've started putting the controller together that was designed by Nik Stanton, a engineer (see previous post). Soldering surface mount component is one tough gig but I am getting close.

The controller plugs into a standalone, single chip computer that I built from a kit called the 'Maximite'. Its a very cool little device that has a built in BASIC interpreter and 20 I/O pins that you can individual configure as digital or analog input or outputs. This is the 'intelligence' and the controller I'm soldering up will allow 3 mains loads to be switched on an off based on 2 pressure and 4 temperature sensors in the controller.

One load will be the newly acquired vac pump and the others will be for heating. Originally the idea was to use 500W workshop lamps as the post curing temperatures for the resin I use is only <50 degrees. But then I came across this thread on the ski-builders website for people building their own silicone heat blankets.

One guys, a kiteboard builder!!, also used his as a dye sublimation press which requires around c. 200 degrees C. So the blanket has the potential to be used for curing and doing graphics. A double whammy!!!

The blankets are pretty straight forward. Resistance wire sandwiched between fibreglass matting and wetted out with 2 part silicone rubber that you can get from mould making suppliers. A light dimmer can be used to control the maximum temperature. I'll be able to use the new controller to switch the blanket on and off to maintain the temperature. You can buy standalone PID controllers or you might even be able to get a timer to switch it on and off on a regular cycle once you know how fast the heat dissipates in the mould.

I think the blanket will end up costing around $100 dollars, most of which is the silicone. I believe it will be necessary to use Addition Curing Silicone Rubber as its rated to a higher temperature due to the platinum catalyst it uses. I believe this is what is used for low melt temperature metal casting.


1. Ni-chrome resistance wire ( about 60m for my 150x50 cm blanket). I've order 32SWG which has resistance of 13.68 ohms/m and will space the wires 1.5 cm apart. Ordered from the states via ebay for a total of $14!
2. Fibreglass matting, 2 pieces the size of the blanket plus extra length to accommodate the connectors
3. Drywall tape - this is the fibreglass tape used on Drywall ( Gyprock here in Aus). Used for holding the heating wire in place prior to pouring the rubber.
4. 1-1.5 kg of addition curing silicone rubber. On skibuilders, people are using rubber with a Shore A hardness of around 40. My local sources only stock 28A but given I am not using a press I am not too worried about the mechanical resilience of it. Goes for about $65 / kg but is much cheaper than buying silicone rubber sheets. I did come across some Teflon rubber BBQ mats on eBay that are 150x50cm and would b perfect but the challenge of bonding the fibreglass/wire element to it has got me stumped.
5.  A connector bar for the mains. For less than about 150 degree you could solder the resistance wire (or at least solder tube crimped over the end of it ) to a bus bar of some sort. People appear to have used Aluminium strip but am a bit iffy about that for 200 degrees.
6. Circuit break is probable a very good idea too in case it shorts ....

UPDATE: It seems that you get to 200 degree c you need power density of 0.5 W/ cm^2. Add that up over the size of the proposed blanket and it translates to about 3 W/in^2 or 3.7KW. It seems that the highest rating for a single outlet on the mains power is 2.4kw. However, this limit may be due to the rating of materials in the outlets themselves as its clearly possible to have more than one heavy use device running at the same time in the house. So this may mean that I need to have 2 circuits in the blanket each with a separate plugs so it can go into two outlets to get to dye sub temps. I need to check this one with an electrician. If not possible to do this economically then I will change my plan to make 2 x 1 kw blankets. Based on the ski builders thread this is enough to get to 90 degrees C no problem which will cover off all epoxy curing , maybe even re-gelling pre-preg resin and the dye sub press will have to use some other tech.

Friday, July 27, 2012

Avoiding voids in the laminate

Its been a few months since the last chance I had to spend time on the boards and lots has been happening. Have been fitting out a van to be a mobile home for our now regular trip to Far North Queensland 3000 km from home.

Arrived in Cairns about 3 weeks ago and the trade winds have been kind. Have had a good number of sessions and a good number of rest days. I've only been riding the 137x44cm Fat Boy board ('the board that should have never been'). I can not sing the praises of this board enough. I've had at least twice the amount of time on the water as any other kiter and when the wind picks up to 20+ knots there is no problem holding it down and have even landed more and better Raley to blinds than before. I shifted the foot pads down towards the heal side edge which moved it maybe 1cm or so and the ability to load and pop has been greatly improved. I've going to experiment with this design some more when I get back. I'm going to leave the outline the same but just play with stiffening it in the middle by changing the reinforcement material.

Anyhow, have been chatting with Juko about avoiding voids on the surface of the board. He suggested using the 1 oz CSM tissue ('scrim')  that I tried working with in the Mini-Me's pre-cured top and bottom sheet. The issue I had with that stuff is that the binder in the tissue is so light on that as soon as I touched it stuck to the tools and was pulled apart. However, Juko's tip was to put the tissue down and put a layer of reinforcement over the top before wetting it out. According to Juko the voids are due to the resin in the cloth being wicked away  along the fibres which leaves voids where they intersect. The tissue is CSM so the random orientation doesn't suffer from voids like woven cloth and so you end up with a better finish.

Monday, April 30, 2012

B8 WakeUP - Wake style board

Had a fantastic 20-25 knot, messy surf session on Sunday. I took the light wind board with 2" fins and 10m RPM and the combo was great. Despite dubbing the Lightwind Board the 'Board that should have never been' its turned out be the best performing board I've made so far - a genuine all-rounder with great light wind performance along with some of the trade-off's that you get for 'All rounding a board'.

In particular, it makes chop almost invisible because the board is thin ( 6mm) and very flexible. The flex is not in the tips but in the middle as the tips are the same thickness all the way along. This means that the when the tip is loaded up it transfers the load along the board to the middle. This means that everywhere along the length of the board absorbs the impact of the chop rather than the tips taking the lions shares as would be the case for typical profiles. The trade off is that the board does load and pop as well because ( from what I have been told) much of a board's pop relies on stiffness in the middle. Maybe so that all the energy when loading up is stored in the kite lines and not in the board as it deforms. As a result you need to drive the board through with your legs to get the rotation and let the kite provide the lift rather than being slingshot-ed by the kite lines as you release from the water. This is actually very good in light wind conditions when you can't load the board but in stronger winds not so good.

The width is also a bit challenging for loading the board up in stronger winds. The force you can exert at the rail with your heals is around 1/2-1/3 of what you can do with a 39-40 cm board because the distance form (my) heal to the rail in a 39cm wide board is about 2cm while on the 44cm boards its more like 4-5cm or more than twice the distance hence 1/2 the force. Basically, the board wants to lay flat. This also makes me think that choice of board should not only take into account your weight but also your foot size. Anyhow, this was the inspiration for trying something more along the lines of a Darkside (slingshot) style board: long with lots of rocker but not unusually wide.

So I've put together a design in Board Off for a 138 x 41 cm 40mm rocker and no concave. The Darkside used 0.75" fins ( basically nothing there) but for choppier conditions I'm going to put 1.25-1.5" fins.

All the details and the design are in the Board Design page on the right hand side at the bottom of the page. B8 - WakeUP

Haven't decide the core profile yet. By not using concave the board will be materially less stiff and so I'm thinking to increase the middle thickness a bit with a 7mm core and some more carbon in short sections of just in the middle and leaving the tips at 6mm. Preliminary Flex modelling of the board suggests the additional carbon (additional to the B7 Lightwind Board) might stiffen it too much and loose the chop handling. Still playing with it.

Tuesday, April 3, 2012

Fabric and Urethan precured topsheets + Rail trimming

Precured topsheets of fabric and urethane - no glass in the pile. This looks like a better approach to topsheets compared to the heavy version I made last time using fibreglass

Also, check out this skateboard making video at around the 3 minute mark for a great setup for trimming the board using the original template.

Monday, April 2, 2012

Pressure & Temperature Controller

I recently used one of the leading crowd sourcing sites to find an electrical engineer to design a controller unit for a planned upgrade to the rocker table. I realised after seeing the homepage on that I am indeed a late comer to the party as the number of projects completed is a touch over 1.5 million.

The project was to design the controller and PCB for a temperature and pressure controller unit that would interface with the recent microcontroller based, standalone computer kit that I put together called the Maximite. The controller needed to be able to take input from 4 temperature sensors and 2 vac pressure sensors and be able to switch 3 independent loads of up to 1 kw each (heat lamps, vac pump + 1). The Maximite will provide the intelligence for the controller as well as being able to log the temperature and pressure data.

I posted the project on Freelancer and within a matter of 1/2 hour bids started to come in on the project. The bids varied widely in price and presentation. I eventually awarded the project to an electrical engineer in the UK - Nik Staunton. It was an interesting experience as Nik's bid was higher than most of the other bids yet when his proposal came in it took almost no time to decide to award it to him. Its a very interesting thing about how we make such decisions. In this case I was looking to hire a supplier I have never met and will never meet, who I never heard of and through a site I have never used before. Part of process was actually working out how to select someone although the search was a subconscious one.

Its interesting the cues you take in when you think your asking 'who' but actually trying to answer 'how'. Like gazing into clouds our minds are able to construct a reality based on light and dark spots in fog and so too I found myself building solid pictures of the bidders based on the oddest cues, plus I have an underlying desire to take a risk out of respect for this brand new world of procurement. Then Nik's bid came in and was at the higher end of the bids but included a professional scope of work that demonstrated an understanding of the project and a familiar level of professionalism and it was then that I realised that Freelancer is not a brave new world its just a different way of the doing the same common sense thing I would do if I was hiring someone down the road - paying to minimise risk; minimise the risk of being electrocuted, the risk of getting a dud product, the risk of my $$ disappearing into the ether.

So to the credit of my 'Ah ha' moment Nik delivered the project  ahead of schedule and with supporting documentation, bill of materials and all the files that I needed to get the boards made.

A very good first experience and one that I plan on repeating.

As for the board, I found a local manufacturer who will make the bare boards ( no components) at $130 for 2 ( most of which is set up cost) - very reasonable for prototype boards. I'm yet to price the components.

If you are looking for a bespoke electronics project I can highly recommend Nik, as I've done online ( I promise no kick backs here just wanting to share my successes with others) or via

Thursday, March 22, 2012

Uploaded 1:1 Plans

I've moved the pages tabs to the right side and added a new page where the 1:1 scale plans for the boards and rocker jigs can be downloaded directly. I have also added a new version of BoardOff that has a few bug fixes and has an additional chart showing the contribution of each component of the construction to the stiffness of the board.

Thursday, March 15, 2012

Navis Boards - A rare glimpse into the building of a board business

Over the last few months I've had the rare privilege to take a look inside the making of a kiteboards building business - Navis Boards which is going live in mid-April.

This is not a case of a back shed operator trying to build one board for himself and one to sell. No indeed. Mirsad Cviko, based over in Sweden, started with passion for kiting, a blank sheet of paper and in the middle of a one of the poorest economic climates in most of our memories secured a financial backer, went about researching the hell out of how to make the greenest kiteboards around and started to source and build industrial strength equipment which recently all came together for a first test pressing.

Part of the Mirsad's great story owes a debt to global trade made accessible to anyone with a Commodore 64 or better:) . It's made it possible for a startup on the banks of the Baltic Sea to source niche products from far flung corners of the world. Bio-epoxy from the US, Paulownia wood from Slovenia, Basalt Fibre ( yes that's right spun volcanic lava that requires no doping with nasty impurities to enhance its properties likes fibreglass does and it's 100% recyclable) from Europe (and I jumped on the bandwagon and looked at sourcing some from China via and accessories from Taiwan!!! Maaate, every board is a little slice of the united nations in kiteboard form:)

One of the other things that has been impressive to watch is how he's been able to reach out and engage his very talent group of friends and family. Engineers to put together this pneumatic press capable of 90 psi (i.e around 36 tonnes of force over the surface of the board) from the mother of all I-beams,

Dad helped properly wire  this dual PID temperature controller for driving the silicon heat blankets for speeding up curing while toughening the resin ....

 ..... and not only are there techo's but there's artist among them as well

 Its easy to get excited about a project yourself but to be able to get other people excited about it is a credit to his leadership skills. And here's the kicker... Mirsad is an engineer and being an engineer myself I know that people don't often compute so he's obviously got both sides of the brain working on this project.

And here's what is all about..

Great work Mirsad. Looking forward to seeing the first board roll off the production line!!!

Wednesday, March 14, 2012

B6 - Mini-me off the table

So finally off the table and cleaned up ready for drilling.

The bottom came out very smooth. Putting down the coat of resin first and letting it cure worked well. No sign of the uneven surface of the core due to the carbon tape. Color came out a bit blotchy. This is the second time I've had the white pigment separate out under pressure and I'm starting to think that the pressure is sufficient to cause the different molecular weight components to separate.

Interesting also to note with the topsheet, pre-cured skin which cured for 24 horus before I put the white fill coat over the back still ended up having the white fill coat diffuse through into parts of the encapsulated graphics. I guess this shows that even though the resin appears to be cured it is still in a fluid state for a long time albeit a very viscous one. The only way I can see to fix this is I continue with the pigment in the resin is to speed up the curing by elevating the temperature for post -cure. the better option would seem to be to use opaque material as backing for the pre-cured skin.

Overall there were a lot of improvements in finished product that I'll carry over into the next one. Two things of note straight away that did work.

i) I layed the board up on a flat table and then bagged in and evacuated it down to c 20 in Hg. This meant that when I bent it into the rocker table the top skin could not slide over core and so it buckled. I noticed this while it was under the vacuum but it was too late by then. The buckling is very obvious in the right light. Fortunately it shouldn't affect it structurally as the potential voids underneath are filled with resin

ii) With an impervious top sheet almost no resin was squeezed out from the top of the board. This was exacerbated by the curves on the top with the surface stepping down from one layer to the next. This seems to have created a resin trap for resin being squeezed out and around the contours there is a noticeable deposits of resin under the topsheet. Also the board turned out heavy as a result of this and the extra resin for the topsheet and the 'gel coat' bottom each of which used around 200 gms of resin. As a result the board came out at 2.7kg without accessories. Well over 500gm heavier that other similar efforts.
Ripples due to 'pre-clamping' the topskin to the core before bending in rocker table. Pink color is courtesy of Picassa!

Do's, Don'ts and Don't Knows to follow.

Tuesday, March 13, 2012

Gathering intell on abrassion resistant materials

I've added a new page to the blog 'misc. tech stuff' to collect together info on abrasion resistant materials for use as a bottomsheet alternative to UHMW or PBT (which I can't source). I'm hoping to find something to play with in the home lab. Heat bonded nylon (although nylon does absorb some water) and sintered HDPE (after being ground up) seem to be the front runners but just researching at the moment.

Also, if you're an equipment junkie check out the great resource that Mirsad at Navis Boards put me on to.

Saturday, March 10, 2012

B6 'Mini-Me' under the pump

Started putting the next board together last night.

I previously poured the inserts and left the core in 4 pieces to help put the concave in it without having to fight against the stiffness of a single piece core.

In the B5-Light Wind board I used 50mm strips of 6mm core and this worked well. I left these as 100mm widths just to see if it still preserved the concave as it did previously.

The set up this time is

4oz e-glass pre-cured topsheet with encapsulated graphics printed on tissue paper
450 gm stitched e-glass ( this stuff is a pleasure to work with)
2x 65mm uni-directional carbon stips the full length of the board including over the tips
8mm paulownia wood core thinning to 4.5mm at the rails
4.5mm ABS plastic rails abraded but not heat treated.
2x 65mm uni-carbon strips
450 gm stitched e-glass
160 gm e-glass
pre-cured 'gel coat' of epoxy with white pigment (left to sure for 2 hours before dong rest of lay-up)

'gel coat' of epoxy - c. 200gm.

Although its not recommended on the forums due to chance of explosion, I heated the 'gel coat' resin in the microwave for 30 seconds and then let it stand for about 1 minute so that it would start to thicken before I applied it to the surface. The reason is that the FGI resin thin enough that it pools on the perspex rocker table top. Letting it thicken, paint it on and then paint over any holes that opened up in the coat ( this happened for about 10 mins) allowed me to get a full coverage on the perspex.

The kit of bits
Under the pump
Then I just assembled it all and put in under a vacuum.

I used 200 gm resin for the bottom 'gel coat'
450 gm resin for the 160gm and 450 gm glass on underside and for gluing the core and rails in place.
50gm of resin to make filler with q-cell to put around the area where the two decks joined as I wasn't sure whether the top sheet would bridge over this join so I wanted to make sure there was something there to fill the void
300 gm of resin for final 450gm stitched glass.

So it was a fairly resin rich layup this time. A reasonable amount should be squeezed out but I wanted to saturate things because I wanted the resin to push into the joins between and around the core pieces.

I layed the whole thing up flat and then put it into the bag and evacuated it before moving it to the table. This turned out to cause a problem with the top sheet. I took the pressure to about 20 inHG (2/3 atmos) and when I then clamped the board into the rocker table the topsheet buckled, presumable because it was clamped too tightly for it to slide over the rest of the layup. I think that the area under the buckled area should be filed with resin because it was pretty well sealed so there was no way air could get sucked in. Only time will tell. If it has an air void then this is where the baord will fail.

Its been under the pump for about 12 hours now and I'll going to leave it for 24 before I take it off.

It was a slow layup this time at 1 hr 45 mins but it was a cool night so the resin was still workable. However, the process of assembling it as a kit doesn't seem to have improved the process greatly in my set up because the hidden time sink is designing the templates and moulds etc to deal with the poor tolerances that I can achieve in my set up while the pieces fo 'tools' still functioning as intended. For example, the mould piece that clamps the rails to the core and holds the core together from the sides needs to accommodate rails of slightly varying thickness and moulded rail pieces that don't quite conform to the outline of the core. This means endless tweeking in situ which is time since. I think that v. tight tolerances are key to making this approach a net benefit.

Also, the reusable vac bag hasn't proven to be a great success either.  I've used vynl table protector (1mm thick) and despite the apparent strength of it it is relatively easy to puncture and so I have had a real stuggle to maintain a good seal on it. This is another tick for pnumatic presses. I have been thinking about possibility of pouring concrete moulds........

Time to do some rethinking.......

Thursday, March 8, 2012

Wow. I wanted to make a temperature and vac pressure controller to use in the Maximite, standalone PIC based computer that I built from a kit a while ago. I wanted to be able to monitor the temperature and switch heat lamps on an off as well as keep the vac pressure within a range rather than at a set point.

Although I spent 5 years studying electrical engineering I can't design electronics to save my life so I thought I try outsourcing it via Its the first time I've used it and after posting it up last night I now have 10 bids on the project from 6 different countries from people who've done electronics design up to military hardware levels!!!! Wow!!! Stay tuned for the outcome..

Monday, March 5, 2012

B6 Mini-Me underway

The light wind board has been going so well that I decided push ahead with the scaled down version for bigger wind and see what characteristics carry over as size reduced. Re-templated and cut it out on the weekend.

The core will be 8mm thick so it meant creating 2 decks which means that there is the extra step gluing (and waiting) which I've wanted to avoid. Only remedy would be to use thicker core material and work out some way of routing the top deck contours.

I've haven't glued all the planks together to form the core, just built up the two decks so there are now 4 pieces. Assembling the pieces at the time of the lay up seems to work well to reduce spring back of concave and so I'm going to stick to that process here.

The cut decks prior to gluing together

Glued and under the vac bag.
The target board design from BoardOff

Sunday, February 26, 2012

Started desktop version of BoardOff

I've decided to put together a desktop version of BoardOff design tool with the goal of making more intuitive to use than the Excel workbook version. It will have the same main section (outline, rocker, flex) but I'm going to try to improve each of these over time but adding visual design tools, improved flex modelling and improved easy of comparing different designs.

I'm going to use C#.NET because its the only language I don't have a really step learning curve with so it means that it will run on windows machines and because its not a WPF application it means that for folks using other operating systems you should be able to run it if you install MONO ( the open source .NET libraries).

So, it anyone has any suggestions on functions and features to add then please send them my way so I really make it useful and powerful.

Saturday, February 25, 2012

Pre-cured sheet

I just finished my first attempt at pre-curing a topsheet and it turned out okay.

I bought 1oz surface tissue which is 1oz CSM matting. It has a small amount of binder in it but as it turns you out can't wet it out with a squeegee or roller without it coming apart. So I had to do some remedial work real time.

firstly , I masking taped some plastic film to a sheet of Perspex. Then, I painted a good layer of resin on the plastic to help avoid air bubbles on the underside of the first layer of glass. I figured the surface tissue would be thin enough to not need wetting out first. I've seen in a video RoadToRoad sent me that the key to a mirror finish is to put resin on the surface first, wet out the glass on a separate table before placing over the wet surface.

So I placed the surface tissue over the wet plastic film and poured 80gm of resin which should have been plenty but it seemed like it was only half as much as needed. I suspect the resin ratio for CSM is much higher. Anyhow, I placed the surface tissue down and poured the resin on. that's when I realised I couldn't spread the resin out. it pulled the surface tissue apart and the fibres balled up like fairy floss. So to fix it I decided to push ahead with the whole layup and hope the vacuum would be enough to push it through, which it mostly did.

So here's the pile from bottom up:
  1. plastic film stretched and taped on flat surface
  2. liberaly coat of resin on the plastic to reduce bubbles trapped under the subsequent layer of cloth
  3. surface tissue (I'll try to get some scrim next time which apparently is like fibre glass gauge and wets out easier.)
  4. graphics printed on tissue paper
  5. 4oz e-glass (next time I try wetting this out seperately)
  6. Peel ply
  7. let it cure under vac.
  8. painted white fill over the back. I used resin with pigment but I was wondering if painting it with epoxy spray paint might also work?
I worked the layup very hard with a roller. There were loads of air bubbles in the weave, so much so that it was like a resin froth on top. I suspect it was air in the CSM glass. I put a layer of peel ply over it all and smoothed it out by hand. I was thinking of just leaving it like that by after 15 mins the edges of the tissue paper that the graphics were printed on were still clearly visible. So I decided to put it under vacuum without any breather material because I didn't want to loose too much resin. I put a loop of felt underlay around the perimeter of the table surface so the bag needed to stretch down to reach the layup.

Vac bagging seemed to be the right move because only after sometime under the vacuum did it vanish. I'm wondering if this is because of the spray adhesive I used to stick it to paper to print on creating a barrier for the resin to soak through.

After it was all cured, the finish on the surface was good but it was milky in places which is from the fine air bubbles. Happy to say that the surface was void free so coating the surface with resin seems to have helped.

I then mixed up resin with white pigment (5%) and painted over the back with a foam brush and let it self settle.

Turned out well. Really flexible, check out the picture of it draped over the table. No concerns now about whether it will conform well with a 3D surface. There were some streaks for uneven thickness of the fill coat I painted over it to get the white background. This probably means that the resin was going off before it had a chance to self level out. It was a hot day so this was probably the cause. Next time I'll try a sponge roller and see if I can get a better result or maybe use gelcoat.

Thursday, February 23, 2012

Thinning on top

For the next board I'm going to make it a bit thicker because I'll be using it in higher wind conditions and in the surf so I want to make sure its up to the task. It's still only going to be 8mm thick but the 33% increase will increase the stiffness of the unlaminated core by around 60% which means around 30% stiffer overall.

My dilemma has been that I've previously tried thinning the 6mm planks that I have using 40 grit sandpaper on a random sander and also using an electric plane and with my emerging woodworking skills the result has been uneven or excruciating long.

To get the 8mm I've decide to thin all the 6mm planks to 4mm because this will mean they are the same thickness as the rail material I'm using so no problems of having to sand it down to avoid bridging and 2mm veneer of paulownia seemed too flimsy to work with and I imaged it would be easy to break. Also, 2 layers of 4mm will be relatively easy to bend while they are not glued together.

So, I took the idea that Fibre n Foam showed in his video of making a jig for using the router and clamped it to the table saw table I made for the HandyCut saw. I used the rail material to set the depth of the router and whao hoo, homemade thicknesser.

The first piece I did was a bit uneven. Only a fraction of a mm but enough to see the obvious furrows. The 4 tips I picked up which lead to the last 2 planks looking almost perfect where

i) make sure you clear the saw dust and shavings off the surface the plank passes over. This is enough to cause the furrows as it makes the surface uneven

ii) make sure the wood plank is pressed flush against the sliding surface by bending the the end of the plank up and so forcing the section near the router bit hard against the surface. A better solution would be to have guides either side of the router to force the plank hard against surface. I'm thinking HDPE strip held down by a compressed spring would be perfect.

iii) If you stop or take pressure of the plank around the router area the bit can easily lift up slightly and the router will put a crop circle on the wood. Feed it through continuously and at a constant rate.

iv) The largest router bit I could find was only 20mm diameter and so I had to keep repositioning it. It only dawned on me half way through that each time I repositioned it I could turn the board around and thin out same section on the other half of the plank. This sped things up.

The final plank was near perfect. The surface was roughed up a bit but I left some extra thickness on there to let me sand it down later.

Sunday, February 19, 2012

Video Guides to BoardOff (WIP)

BoardOff has been downloaded over 1000 times now but there is relatively little in the way of user guides so I've finally got around to starting some tutorials on how to use it. I've done a few screen movies and will keep building the library of videos until all the basics are covered.

I hope you find them useful!

 BoardOff Video Tutorials

Saturday, February 11, 2012

B6 Design - Mini-Me

For the next board I was going to try the light wind board again but this time getting the process right. I still will do this but I'm quite keen to try a scaled down version. Here's a mockup of the design for the next board. Its 130x41cm and othersiwe exactly the same parameters as the light wind board.

I compared this to the Lunacy and its turns out to be very similar. However, the lunacy has very little rocker and is around 11-12mm thick. My version of it will have the same rocker /concave as the lightwind board (now that I have the jigs all set ) and will be be thinner. Hopefully this will help it in the surf and the chop an bit more.

Am going to try to get the production process running a bit smoother this time and hope to pre-cure the topsheet.

Light wind maiden voyage

Hey, I got to test the light wind board in around 15 knots on choppy water. Didn't break!!

Here's a few observations. I can't connect all of them to a feature so all input is welcomed.

i) Very smooth ride, zero spray in the face. I put this down to thin board (6mm) and 30mm rocker which is more than any board I've had before.

ii) Amazing upwind. Tracked up wind better than people on same size kite on surfboards. Strange thing about it. It didn't feel like it was trucking up wind. Normally a lot of force and edging hard is associated with tacking hard upwind but this didn't. I put it down to the very straight rails.

iii) Skatey feel. The extra width (44cm) made it difficult to hold the rails down because of this. The extra distance from my heal to the rail is too much to be able to edge hard. Although its the width that is the driver of this I think the real variable at work here is the distance from heal to edge which depends on your foot size.

Because the board flattened out it slide out easily. Landing jumps  was tricky because it was hard to get the edge it and so the only way to land was to land with the board pointing down wind. I watched another couple of people ride it and the same thing with them. I'm going to increase the fin size ( its got 1.75" fins but am going to put 2" fins which are proportionately larger than the size increase). Other then move the footstraps to one side in the next version and maybe channels I don't know what else could be done.

iv) Light wind coasting - it planed with almost no forward momentum at all. Great light windness

v) It rode over chop without any spray at all but wasn't exactly comfortable. I felt every bump. Each piece of chop was like a ramp and board jumped over each one. The board didn't cut through the chop with a sense of stability like the flatter boards I've ridden. This could be for a few different reasons:
i) The rocker is curved in middle then straight. The straight section would be hitting the chop at a steeper angle than my other flatter board. Maybe this pushes the board up more.
ii) The concave profile is set up so that the concave is largely gone by the time it reaches the footpads. This means that the tips are flat which I believe doesn't spill water as well as concave surfaces.
iii) The thinner board being more flexible than the others means that the tips bend up then recover with bigger amplitudes so you have the chop plus the vibration of the board together.

Not really sure. Could just be as good as it gets. Don't know...

Overall, I'm very happy with it. Landed a few big jumps and it felt tough enough. I'm still tentative about taking it into the big surf. The plan for the next board is to reuse the outline but shrink it to 130x41 and add an extra 2 mm thickness in the middle to stiffen it a bit. Will be interesting to see the impact of reducing the size.

vi) You're definitely aware that its a bigger board. Its takes more to turn it in the air and it feels heavier even though it 3.5 kg (with accessories) which is very similar to my other board. The dimensions must just give it more inertia.

Wednesday, February 8, 2012

QR Codes

These QR codes are great. Discovered that the free scanner I have on the iPhone has a creator as well. The QR codes themselves look cool so thought it would be fun to create some and use them as graphics on the board. The QR codes can containn text or direct you to a website and an number of other things. I though it would be cool to have link to the construction photos of the board and also a write up on the board details.

Here's is the text for the board description. It seems that the more text you add it just adds more QR codes nested in the overall image. Not sure the limit.

Just scan it with you QR scanner

Some more

Monday, February 6, 2012

The board that should never have been pt.2

So there I was, staring down at my precision designed, poorly executed, slick looking wobble board. To coffee table it or not?


Attempts to repair it

Things left out were footpad reinforcement patches and the unidirectional carbon cross straps (65mm). Easy enough to add on and it had been less that 24 hours since the last layer wet down very little surface prep needed. All good.

So why not add the graphics too. Hey, sure. They needed a white background to cover over the carbon so I'll give it a white back ground too. Hey sure.

The plan was to wet out a layer of 4oz glass with clear resin and place graphics down, let that cure a bit and then put a coating of resin with white pigment. So I wet out a layer cloth for the bottom, lay down the carbon cross straps and placed the board on top of it. With the carbon straps being about 0.25 mm thick, this was about 0.5mm where the crossed. With the board laid on top and the perspex underneath, this left the board standing off the surface of the rocker table in a large area around where they crossed. As a result the resin pooled and the vacuum was of no use in removing any air bubbles in the vicinity of the carbon.

Here's the result which gets uglier the closer you get.

You can see the white resin that's pooled around the edges of the carbon giving it the halo effect. This resin has lots of voids in it.

So then I wet out the top layer of glass on a piece of release film and laid the graphics down. This went well and the tissue paper around the graphics vanished and there was no visible diffusion of the ink  (standard ink jet printer ink from Coles supermarket). I had visions of letting it mostly cure and then putting a coat of white resin over the back but I realised I had already put the bottom skin down so I didn't have long enough to wait for it to go off and so I gave it about 1/2 an hour before I added the white resin. This wasn't nearly long enough and as soon as this piece got transferred over and laid down on the top surface of the board, the white resin started to diffuse into the graphics, almost completely obscuring them.

The the final screw up was to use felt carpet underlay as the breather material once I had put everything under the vacuum. Turns out the felt underlays density varies a lot and as a result the denser parts pushed the white resin away and it pooled under the leas dense areas. As a result the board came out with what looks like leprosy with the carbon plainly visible through the blotchy white resin.

Close up of blotchy resin showing the diffusion of white resin into the graphics.
 You can see in the above photo the behaviour of the colored resin. It gathered in the foodpad support areas but was squeezed out of the layer between the partially cured topsheet and the previous top surface of the board.

A closer inspection also shows lots of voids on the top surface. While I worked on the topsheet to get air bubbles out it seems that the lack of bleeder material on top of the glass gave it zero tolerance. The bumpy breather material then seemed to force all the air bubbles into larger voids areas from which the air could escape.

The Don'ts

  1. Don't skimp on your planning. Might be worth listing all the steps and checking everything is ready prior to pouring the resin. Once the clock starts ticking its easy to get distracted and forget a step or two. This is especially true when there is more than just putting the laminate on.
  2. Don't rely on non-cured resin to make carbon invisible
  3. When creating a top sheet on a smooth surface (and especially if vac'ing it) then there seems needs to be breather /bleeder material on one side to give the air bubbles an way to exit. My only concern here in creating pre-cured topsheets is that the breather material may wick too much resin out and leave the top sheet dry. This will need a bit of experimenting.
  4. Given the time and pressure in these process, colored resin will diffuse into resin that is not fully cured so don't apply a fill color over your graphics until the resin they are encapsulated in is fully cured.
  5. Where the thickness of reinforcement materials is not uniform across the entire surface of the board then you need to make sure the table surface or the vac bag can conform to the shape so that resin doesn't pool. On the underside of the board there will need to be something that can, in my case, accommodate a 1/2 mm bump. Maybe some dense rubber matting.
  6. Don't use breather material that is not uniform in density, it will give the board leprosy.

Wednesday, February 1, 2012

The board that should have never been Pt. 1

It all started out fine. The goal, to be able to assemble and glass the board in one pass. I pre-made the inserts, rails cut to size and flame treated, stitched 450gm glass so only one pass was necessary, moulds to hold it all together.

And was I focused, oh yeah. The steps were almost choreographed. So focused and impatient that I ended up forgetting to insert the carbon tape and the footpad reinforcements and the white pigment!!!!!! So I ended up with an efficient, good looking wobble board

....But lots of good things came out of this . One of them was not the board (it's a real pig) but I tried a lot of new things with this one. Some worked brilliantly, some limped over the line but have potential and some ... na.

So the score is:

Do's - 50%
Dont's - 30%
Do know's - 20%

First things first

I started the clock ticking and poured the resin. R180 from FGI with slow hardener because I wasn't sure how long it would take. Pot life is about 40 mins but this extends to a couple of hours workable time once its spread out and the heat generated by curing can easily dissipate.

First I applied just a single layer of mould release onto all the mould pieces.

Then the glass and mould over the top.

Note the Velco (top and bottom) used to hold the mould pieces together. Reusable and strong and can be easily adjusted.

Then it was time to put all the pieces together. This took about 40 mins. I used a paint brush and fingers to get resin into all the joins including the inserts and rails etc. One of the snags was that because I was thinking that the wood grain would just show through, I could not mark the planks in order to make sure they went into the right place. The board is not completely symmetrical so it mattered where every piece, including each insert, was placed. I spent a lot of time working out where bits when. I think next time I need to stick something on each piece to remind me were it all goes. How to do this without contaminating the surface?? Don't know yet. Possibly using Super 77 spray adhesive which Dave tells me works a treat and doesn't interfere with the epoxy bond to the core. Brokites also use this stuff to stick the carbon cloth in place. I could stick tags on and pull them off once its laid down. Doing this would have saved about 15 mins and some angst.

I spent some time preparing the rails. Abraded them and flamed them with a propane torch. 2- 3 close quick passes with some time for them to cool a little in between passes as the plastic will distort. The surface of the plastic at the end felt cindered almost a little chalky. I was careful not to scorch it as I had seen in previous experiments that as soon as you see brown scorch marks on the outside then bubbles will have already formed inside and the plastic will be brittle.

No photos for this stage cause I was focusing (too) hard.

After all assembled on a flat surface I put the next layer of glass, peel ply, paper towels (bleeder material stand in) shade cloth ( a tip from Dave that this stuff makes for great breather material and it did.

Into to full vinyl bag, sealed with packing tape and evacuated it to 80% of vac . At this stage , still on the flat table.

Then I moved the whole lot onto the rocker table jigs which I had covered with felt carpet underlay to reduce the chance of puncturing the bag. Then clamped it down using ratchet straps.

From the first resin mixing to now was 1 hour 33 mins.

With the core not being pre-glued flat, the concave profile across the board was exactly as designed and virtually no spring back given there was not stresses locked into the board width-wise.

24 hours later...

Because the mould pieces around the heal and toe side where the same thickness as the rails it was very little resin caked on the outside of the rail and this also meant that the excess fibreglass could just be trimmed with scissors. The pictures about are of the board straight off the table after trimming off the excess.

The trick I picked up was to put the excess glass away from the mould pieces first so that there is only a little bit of glass overlapping from the rails to the mould. Do this all the way around because when you do this you can then very easily just snap the mould pieces away from the board with the risk of delaminating the rails which is always a risk given that even under the best preparation the glass plastic bond is still not great.

With a core thickness of only 6mm and 450gm/m2 cloth top and bottom the board was very flimsy; very little stiffness lengthwise and in torsion. The unidirectional carbon straps in an X layout were the key to locking it all into place but without these nada.

So decision time. My wife suggested turning it in to a sign. I suggested that was inappropriate and asked her to please leave the room:)

With just a single layer of wood and the more economical glass it is the cheapest effort so far but I decided to go ahead and try to fix it. Nothing ventured nothing gained. In hindsight a nice sign might have been the way to go...

Wrap up of the good 50%

Full bag - yep. Reusable, no wasted tacky tape or vac film which saves about $15-$20 given the small quantities I buy, reliable. If the board has more curves on the top it might have been necessary to add some pleats to the bag to have some excess to conform to the curves as it doesn't stretch very well. With the table surface fully enclosed in the bag the chance of the table being distorted is greatly reduced as the forces top and bottom are balanced. In my previous attempt the force was just down on the board which meant that the table could bend up to meet it and concave disappeared

Mould pieces - yep. Allowed the held everything together very tightly, reduced drastically the amount of effort needed to clean the board up after coming of the table. This is especially true compared to puring the rails and then having to cut the excess wood and glass off. Also allowed the whole 'kit' of core pieces to be really squeezed in together tightly ( and even more so when you bend it into the rocker table as there is some compression even with the slight curves baked into the board) which helped get a good bond but also helped make up for the inevitable gaps due to the slight mismatches between rail and core.

Laying it up flat first - a very solid base to work from and so was just easier to work. Certainly made it easier to work the resin in with the resin roller. Gave much easier access to the work space. Generally just more convenient. Clamping it into the jigs after laying it up flat was easy and again very convenient.

Shade cloth for breather material - yep. Worked great.

Using a fibreglass roller to work out the air bubbles   - yep, again worked well. I have since found out that it might also help greatly to put resin down on the rocker table surface first and wet out the glass on a separate table before laying it over the resin'd surface. This was there are no air bubbles to start with so no change of ending up with the voids on the underside. The top side is a different story and in the absence of plastic topsheet material, pre-curing seems to hold the greatest hope for a shinny finish with graphics and an opaque background.

Assemble in one pass - hmmm. It added more work and time pressure to the layup but it was very efficient to do it all in one pass. For larger volume production runs I think that pre making a kit is probably critical as it will allow processes to be run in parallel rather than in series which is the time killer. However, for 'micro' quantities of production I think there is a middle ground needed if the board shapes are more complex ( surface profiles etc). While it did eliminate the waiting periods for letting inserts cure and then rails stick an then the core planks to glue, I think it would be a bit more difficult to shape all the pieces if the board had several layers. I need to think this through some more because each example against I come up with makes me think of a solution to. Here are some of the issues and resolutions that come to mind

i) Difficulty managing multi-deck shaping because of the large number of unsecured planks of wood - solution use wood the thickness of the board and cut it into narrower strips ( 25 mm). Make them longer than the board and tack glue them or clamp them at the very ends only. Then you could shape the surface, then route out using the template and clamp the pieces in place with the mould to continue working it around the rail areas.
ii) Fine tuning of inserts needed when they are not poured into the core. Just get the sizes more accurate when making the inserts outside the board. Either make the holes in the template a little oversized as the bearing on the router necessarily makes the cutting surface stand off from the template a small amount , enough to required hand working of the inserts to get them to fit. Could use round ABS plastic rod for the inserts as per The mighty might brokites.
iii) Mismatch of the core with the mould - don't screw the mould up in the first place. Make sure the rail widths are exactly the size of the router bit. I feel another home made tool coming on here.

The pro's for this process is that its possible to stockpile many of the pieces needed and then produce a board quickly as needed. Where there is a desire to make a number of the same or similar boards, this hands down necessary. For one and two off's, its a great deal more convenient and fits better with the pieces of time I have available to work on it and a desire not to have the long series of wait times. Both both cases the lack of lateral stresses baked into the board means your concave with survive the test of time.

Con's are that you need to be much more accurate in making the various components otherwise the efficiency gains are lost through having to tweak every bit to make it fit properly. It also potentially makes the shaping process a bit more difficult unless you can find a was to hold all the bits together when shaping it.

I think I am talking myself into persevering with the approach another couple of times.

Next post will be the on the Don'ts....

Monday, January 30, 2012

Peel Ply FYI

Not that this all that relevant for kiteboards but I thought that this was interesting none the less.,%20SAMPE%20(Anaheim)%20MDC%20950072.pdf

In a nutshell it says if you are going to laminate over a cured surface that has had peel ply used over it then you have to clean and sand it v. vigorously as the release agents used on nylon release films will contaminate the surface and cause a weak bond.

This came up in the context of looking at precuring topsheets and playing with the idea of making the skins with peel ply incorporated as part of the 'stack'. That is

- fibreglass scrim or surface tissue ( <2 oz)
- graphics
- nylon release film

The release film being used in place of layer of glass so that a colored background can be applied to the decals instead of having to apply a second, coloured layer of resin after the resin in the surface tissue has cured.

Apparently non-coated nylon will chemically react with epoxy though would have thought that it might need to be done at elevated temperatures to get this to happen or at least insulate the curing stack so that the heat generated during curing can be held in to assist the process.

Maybe using densely woven but thin cotton material might be a better option.

Pre-curing topsheets

I got some great help from XSWind on kiteforum re pre-cure topsheets. Here's the link

... and here's the guts of it.

The purpose is to obtain a thin skin which is resin as that is the only way to obtain a full and deep gloss/sheen.

The topsheet is wetted out on just a sheet of normal glazing glass and then vac bagged flat, there is a or two trick here but I will leave you to discover them to make it perfect.

yes I vac bag mine.

The objective is to make a cured and finished thin laminate.

Thickness is up to you but I normally do a 2oz or thinner scrim layer with decals next followed by a layer of 4oz. Leave to sure then bond

If done right you end up with a completely finished fully glossy outter surface to your board.

Once the topsheet is cured leave thay Maylar if you like sheet attached, dont remove it.
skuff the top sheets bonding side with 40 grit and clean the dust off. Now simply go to your rocker table lay up the normal structural layers and put the pre-cured top sheet on and after the normal vag bagging process has been done, you can remove that film layer to reveal the goodness.
Another tip is "a simple addition to the pile before bagging"

Friday, January 27, 2012

Full Vac Bag

Here's a couple of shots from yesterdays activities. Below is a shot of the dry fitting with the board and mould fully enclosed in the thick vinyl vac bag.Velcro is used to pull the two parts fo mould together tighly. I tried bending the board across the width to length wise to see if the gaps between the planks would open up. They stayed together well enough and I'm guessing if small gaps to open up they will be filled quicly with excess resin from top and bottom.

Here is a visual of the problem I mentioned yesterday about the lack of tight tolerances on the core mould due to me getting the rail width mismatched with the diameter of the router bit and so having to 'hack' it.

I decided to try to have a bit of fun with graphics rather than get to artistic at this stage. I've printed the images on tissue paper and am just working out the best way to add them. The options are to pre-cure a top sheet and put the graphics on the back. Only drama there again arises from mismatched rails.They were 4.5 mm this and the core material is 6mm. So, I've have to do a bit fo profiling on the core and there are a couple of compound curves there I'm worried will cause too much bridging. Alternative is just to use peel ply in the vacuuming and then lay the graphics on top and follow it with an coat of epoxy. The down side there is that it will require elbow grease to get a good finish.

I'd love to try the pre-cured but we'll have to wait and see if I'm up to the challenge.

Thursday, January 26, 2012

Graphics and topsheet finish


After chatting with Peter on the blog and looking around on kiteforum, I think I've finally got a way to make the finish in the top of the board glassy right off the table.

If you search 'Porker' on the kiteforum board builders forum you'll find a really great looking board with a gloss finish right off the table. The maker doesn't give any details of the actual steps except to refer to it as 'pre-cured'. Eureka!!!

I'm guessing this just means a light ply of glass layed up on a sheet of plastic to get a mirror smooth finish on one-side, the side that will face up. Once this is cured it can be used just like the topsheet material Durasurf or PBT which has proven very difficult to source in small quantities in Australia.

So my thinking is just wet out a think layer of 3 or 4 oz glass on a perspex sheet, place a layer of peel ply over the top to blot away the excess resin and leave the surface rough so that you get a good mechanical bond when you use it as a top sheet. But wait, here's the rub. If you use clear resin first, lay the encapsulated graphics down ( I've printed them on tissue paper) then peel ply it. Give it a few hours and then apply a coat of white resin , peel ply it again. By letting the clear layer cure first, the white resin over the top of it won't infuse into the graphics like happened to me last time when I only left it a half hour or so. Any the opaque background means that you won't see any of the voids etc in the layers of laminate when it placed on the top in the lay-up.

Bit fiddly but it means that the topsheets can be made in advance and stock piled.


Core setup

Today I cut the core out and did the first dry fitting of all the bits I put together so far.

The overarching goal for this evolved to be more about getting the process of making the board run smoother and try to eliminate the multiple curing cycles needed for inserts, rails etc by being able to do them all in one go. While in principal the approach of putting a kit of pieces together and then gluing everything together at the same time as doing the glassing is right approach, I've come to realise that efficiency is lost if the pieces you create are not within very tight tolerances. For example, i used the same size speed bore for the moulds to make the inserts as I did for drilling the insert holes in the template for the board. However, it turns out the the moulds for the inserts where not drilled vertically, just a little bit off but enough that each of the inserts needed to be sanded to fit and I lost about 1 hours and did lots of fiddly dusty work. So, next time round I'm going to focus on getting the tolerances on everything very tight.

Anyhow, had a chance to tinker today. Cut the core and did a dry lay up of the core 'kit' and tried a new reusable vac bag made from thick vinyl.

First thing was to put double sided tape down to hold the loose planks while i routed around the template

Then without any sanding I did a dry fitting to see how tighly the whole thing would hold together and if enough pressure was being applied to hold the rails on.

The pieces of the mould are pulled together using gaffer tape. Soon after this shot, the tape tore under the pressure. Then I had the ah moment and stuck some Velcro ( hook and loop) at both end. Worked like a charm. Was adjustable, strong and when is clamped down inside the bag, it hold tight.

The core needed a bit of trimming here and there. This was because I made a mistake when I got the rails material cut. I got 10mm strips but my router bit is 9.5mm. This was enough to require re-routing the moulds to accommodate the larger rails and of course the freehand work was a mess so the rails were not a tight fit straight away. After about 1/2 of work it was all good.

I put the mould and core inside a full bag mag of thick vinyl. The long sides I sealed with tacky tape but just used masking tape at the opening where I put the board into. Sealed very well and was easy to under. I went with the thick vinyl because the plan is to lay it up flat, put it in the bag and evacuate it and then form it in the jig. Having the full bag means that I won't have the problem of the table surface bending because this time the clamping pressure is on both sides. There will be a lot of pressure on the bag at the points where it lays on the jigs so I thought that think vinyl was the way to go.

I made the bag very oversized. The vinyl seals to itself very well and so the oversized bag, I suspect, help get a really good seal.

Monday, January 23, 2012

Graphics and substitute reinforcement

Philip the kite surfboard maker gave me a tip on doing encapsulated graphics. Print them on tissue paper using an inkjet printer. To make sure the tissue paper feeds through the printer without getting crumpled you can spray an A4 sheet of standard paper with a very light coat of spray on adhesive such as kwik grip in an aerosol can( that you can buy from Bunnings hardware) and press the tissue paper onto it. Worked like a charm.

I guess you need to make it very light so that you can peel it off again and so that you don't make it water proof. You can encapsulate the tissue paper between layers of glass or just press it into the top before you bag it. Apparent both work well and for the top surface, at least, the extra scratch resistance of encapsulating it is probably not an issue.

I was going you 2x200gm layers of eglass on this board but in persuit of the goal of reducing the number of steps I 'lashed' out and bought some 450gm 0/90 stiched e-glass. This should be stronger than the 2 layers of woven e-glass because stiched material is basically 2 layers of unidirecetion glass with a small about of bonding agent and then layers stitched together. This removers the crimp that reduced the strength and effective elastic modulus of the reinforcement.

453 gm stitched e-glass
It comes in 1270mm widths at FGI and this turns out to make it more economical than buying the 200gm woven fabric because its wide enough to use for at least 2 boards if not 3 whereas the widths the 200gm came in meant that it was enough for one board width and a lot of wastage.

However, this is likely to make the board stiffer than BoardOff would estimate because the 50% reduction in the theoretical elastic modulus of e-glass used to model the woven fabric will probably underestimate it for this fabric. This means a stiffer board.

I was eyeing off the triaxial glass but the lightest weight is 750gm/sqm which would translate into about 1.4 kg compared to around 800gms. Given its a light wind board the extra strength and weight might be overkill.