School boy error

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Rupert
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Post by Rupert » Thu Sep 01, 2005 5:56 pm

Just before we went away, I started shaping a new centreboard. left it for 3 weeks, and I'm sure you all can work out what happened, though it didn't occur to me in my hurry to leave. Anyone any ideas how to un warp a centreboard in a day? Or anyone got a board for sale to fit a ToY? Might be Saskia coming to Bowmoor after all, as I've not time to make another before then, with many other things to do...
Rupert

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Ed
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Post by Ed » Thu Sep 01, 2005 7:04 pm

Which way has it warped.....across grain or down length?

presuming across grain which is more likely....it is possible....

1) soak it in bath of hot water for an hour or so then bring out clamp flat and let dry.

2) wet convex side and then put out in sunlight for an hour or so....but keep a watch on it.

3) (not for the fainthearted)....if nothing else works, and it is quite strong, in otherwords you can't bend it back by hand.....put it back through the thickneser.....get it flat....and then start again with either a thinner board or build up thickness with a layer of veneer/extra glass.

I have had limited sucsess with this kind of thing.....wood does move....but can be persuaded to move back....as you know of course!

Once you have got it flat (and dry), chuck on some epoxy and cloth quick.....maybe even some uni-carbon.

think it is like fixing a mast.....sometimes it works....and sometimes not!!

Tell me how you get on, I have got a jollyboat board that I have had to revert to method 3.....its flat, but only about 10-12 mm thick at present.....sposed to fit into J3's very thin case....still might be interesting....or maybe cost a fortune in carbon!

Good luck

eib
Ed Bremner
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chris
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Post by chris » Thu Sep 01, 2005 8:07 pm

A steamy stripper (sorry - as in a wallpaper stripper) can give enough steam to bend (or unbend) things. For wood fibres to slide to a new position they should reach 100degrees. bend it beyond the straight position so that it can settle back. Steam the inside of the curve ie the side you need to shrink.
Then trim up again.
In all probability this may only be 60% successfull as a permanent cure.
Quarter sawn timber should be more stable but many decent boards are not!
I'm sure you'll have it done by Bowmore. If you only go round in circles we'll understand.

Rupert
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Post by Rupert » Fri Sep 02, 2005 8:49 am

Thanks guys - I'm at the point now of deciding to do the job properly and make a better one, and bring Saskia along, rather than waste time on a lost cause...Time to start looking for a sitter for the kids...
Rupert

Garry R
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Post by Garry R » Fri Sep 02, 2005 8:55 am

Put one child at each end of the board with a large pile of crisps, coke and BigMacs in the centre. Tell them it's a new see saw game and they have to sit there for the weekend without moving. By Sunday night the board will be straight and the kids will have been taken care of!!! When they inherit the ToY they will appreciate that it goes in a straight line due to their efforts!!

JimC
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Post by JimC » Fri Sep 02, 2005 10:21 pm

How shaped is it at the moment? What's the core made of? If its a single piece you could try cutting it into lengthwise strips and 180 rotating alternate strips then reshape it. You'll still lose a fair bit of material reshaping but at least it won't warp again. Then glass/carbon coat up to size.

Brian E. Evans
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Post by Brian E. Evans » Sat Sep 03, 2005 7:51 am

At this stage of the game it may be too late for the weekend. If you have a heat gun or a very powerful hair dryer, you might try soaking the board in water, then wrapping it in a wet towel then heating the toweling until it just starts to scorch, keep the gun moving so you do not overheat any one spot.I use this technique for bending plywood. Dont forget to apply your bending/straightening load as you do this and keep it there until the wood is cold again. If that does not work , throw it in the corner and ignore it for three weeks, when you come back it may be straight.
B.E.

Rupert
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Post by Rupert » Sat Sep 03, 2005 11:28 am

Thank you for all the advice...oddly, the final one is the one I'm going for, leaving it the other way up...the board it is made from is an old blank Mark found me, and I don't think it is worth the cost of the glass and resin putting it right. I'm on the look out now for an old board out of a dead dinghy, as this is a deliberatly low tech boat, and I'm avoiding both sheathing anything and also avoiding as much work as possible... A scorpion board would be about right, but anything could be converted.
Rupert

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