Dean in WA has got a great set up that is well worth checking out. He's a perpetual innovator!
http://downunderbloghr.blogspot.com/2011/11/vacuum-bag-vreca-za-vakum.html?showComment=1321703327378#c6423100218731273409
I love the rocker table idea. He basically took a plaster mould of an existing board and tada!!! Instant rocker table which can be placed completely inside a sturdy vacuum bag - no clamping, no jigs. Brilliant!!!! He' used 1mm vinyl for the vac bag.
I've been thinking that it would be a lot easier with my set up to lay the board up with the acrylic part of the rocker table surface flat. Put the whole thing in a vac bag rather than fuck around with tacky tape and then clamp it down. I'm thinking that the vinyl would be strong enough to take the pressure of the jigs clamping down on it. Provided that there was plenty of bleeder material to soak up the excess resin then the bag would be reusable.
In the video by Fibre and Foam ( search youtube for it) her used vinyl for the vac bag too and it worked fine. However, he put the vinyl directly onto the board surface without breather/bleeder material and it left a ripple effect on the surface of the board because without the breather material, once it comes in contact with the resin, the resin is sticky enough that its nearly impossible to apply enough force to stretch the surface tight.
Thanks Matt.
ReplyDeleteThe plaster mold + vinyl vac bag worked well and my board is finally glued (in an 'oven' at 50C, but had drama with all of this:). Vac bag is reusable, no probs.
Yes, forgotten to add breather:( Added only bleeder fabric and it's true, it didn't glue well with only the vinyl pressure. But I'm not worried since this is around the top bamboo ply, so can easily sand it off.
Interestingly, it didn't stick only on a few small areas and where the vinyl didn't bend (breather, breath..:).
The rest is like a glass. Looks well done and glued. Will see. Might vac it again at 10-15inM...Is that enough pressure?
In overall I'm very pleased with a first run! Flex and rocker is great, concave will fix (if I decide to), and the board is light (2.5kg).
Dean
PS Not sure about 12mm ply. Top surface under concave will be under tension, bottom under compression. The wood grain should be vertical to tension, not longitudinal like on my board as well. To solve this, I might glue a small squarish ply on top with a vertical grain.
Or, make a rocker and than sand out concave? Plenty of space in 12mm :)
Well done!! Can't wait to see it on the water!!
ReplyDelete2.5 kg is a great outcome and especially so because its made from ply.
What sort of bleeder material did you use? I splurged and bought some proper stuff for $5/m !! and it left a very fine imprint on the surface of the board which would have been perfect for paiting resin onto. However, I tried vac film straight onto the board (as a seperate and final finishing) and it had lots of wrinkles in it - wrecked the look of it. My learning was to hand finish the surfaces and not try to get the film/mould to do all the work.
I'm going to use Paulownia not ply. Its feels like a dense balsa wood. Its very light but you cant just cut through it with a Stanley knife. Was the vacuum pressure you used enough to bend you board flush to the rocker table??
Cheers
Again having problems with comments:(
ReplyDeleteWhere did it go?
Anyway, the bleeder is very, very slippery on a touch and got it from my local shop. Think it's much cheaper. No wrinkles, and yes, very fine imprint.
Vac around 15inHg was enough to make a rocker. More than that was needed for concave.
Since I was running late, the vac pump was working no more than 10 times by a few minutes:)
But it was quite cold, around 10pm, when I got the vac bag solved, so I recon epoxy was still somehow workable. Than I've put 'oven' on top, applied pressure and after 12pm left it as is in the 'oven'.
This would suggest that the 'oven' did a job in about 2-2.5 hours since after that there was no vacuum in a bag and the board is still in a perfect shape!
Flex is just phenomenal! It's exactly the same as my commercial board, comparable in a mm!