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