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 Alibaba.com) 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.

http://www.happymonkeysnowboards.com/MonkeyWiki/Equipment_Overview

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

Freelancer.com

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 freelancer.com. 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