Bending plywood Paipos

What works and what doesn't. Share design ideas, references and contacts for paipo board builders.
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Interests: Building Paipo boards! I’m building one for my husband and looking for some more information

Bending plywood Paipos

Unread post by amberswoodshop » Wed Feb 12, 2020 2:18 pm

Hi all!
I am in the process of making a Paipo for my husband! I’m using 1/2” marine grade Douglas fir plywood. We have the shape cut out, tracing a borrowed Paipo he likes. I was able to get 4 out of the full sheet of plywood. The first I bent using a lot of hot water and a lot of weight. I’m worried I used too much hot water as there are little black spots on it now that don’t entirely sand off :?

How have you bent plywood? And how long have you left the weight on it? I left the weight on overnight and I’m concerned that that’s what caused the black spots, water trapped under the weights. Also what kind of finish is best? I have a can of Thompson’s water seal leftover from a previous project, I was thinking to use that. And my shop isn’t set up for fiberglass yet so I can’t glass it. Any advice would be greatly appreciated!

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Re: Bending plywood Paipos

Unread post by bgreen » Wed Feb 12, 2020 4:38 pm

Why don't you send some photos. I've never tried to bend plywood, but the archives have some information. Your husband is a lucky guy.

There are 3 basic methods to bend ply: 1) soak as you did, 2) steam and 3) clamp.

1) From Poobah 2010
I've been out of board building for about a year, and now I'm dropping back in with a poplar and pine psuedo Penzance paipo. The perimeter was pirated from an old Penzance board...a Crest model from the West Cornwall Woodwork. My Cali version of a Cornish board is made of poplar 1 x 12, rather than the marine plywood of the original.

Boil bending the nose got me very close to the 1 3/4" nose kick of the original. I got 1/8" more and I'm not done with the final sanding yet. I soaked the nose end of the board for three days in a rain barrel (nonchlorinated water.) Then boiled the nose in a large pot of regular tap water for about 30 minutes, and then clamped a curved (shaped) chunk of 2 x 6 redwood down on the top of the nose. The edge of the bottom of the nose rested on a curved chunk of 4 x 4 redwood.

2) Clamping method. ... t=10#p2780

The French and Spanish used presses: ... soro.shtml
They glued their own ply.

3) Boiling water. ... -cope.html
The original parallel-sided boards later gave way to tapered models ( see cutting plan ), which still made 8 boards per sheet.
After cutting them out with a saw, the board`s noses were wedged into the tops of drums of boiling water for an hour : `Getting the nose kick was pretty crude, really. Bert had some long pole ladders where we would jam the hot and wet nose down under one rung, and pull down and tie the rest of the board against the ladder with rope. Just one long ladder could take a dozen or so boards tied down in a row. A day or two later they were bent for good, and dry, and could be untied and finished off.`
They didn`t use a jig or mould to get the nose kick, as these would stop air getting to the wood and drying it out. However the `ladder` method produced many different radius curves, and in different places along the boards - it all depended how much nose was jammed under the rung, and where and how tight the ropes were tied. Due to this variety people now assume many companies were making boards. No, there were only a few.

4) wikihow

The shorter the board, the less need for kick.

Finishes. varnish, resin or tung or a linseed mixture are all options.

More build info here: ... =569#p4839 ... aipo-board


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Re: Bending plywood Paipos

Unread post by GeoffreyLevens » Thu Feb 13, 2020 11:53 am

The glue up your own I did once. Forget what glue I used but got thin sheets of luan I think. Laid each layer cross grain to the previous one. I used shims, 2X4's, etc on garage floor to create a "rocker table". Slathered on the glue and put the stack on the shims. Weighted w/ sand bags, kettlebells, whatever I had around at the time. Tapped and nudged shims to adjust the way I wanted it. Came out quite well.

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Re: Bending plywood Paipos

Unread post by Atlantasurfer » Thu Feb 20, 2020 8:40 pm

For sealing ply pianos Spar Urethane is close to perfect.

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Re: Bending plywood Paipos

Unread post by Uncle Grumpy » Thu Feb 20, 2020 9:22 pm

Works pretty good on Paipos too. ;)
Paipo surfer in repose,
Nose on the nose,
No grunting he-man pose.
See how fast he goes!
What is it he knows?

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Re: Bending plywood Paipos

Unread post by zensuni » Sat Apr 18, 2020 10:38 am

That's a great gift for your husband.
I bent plywood once for a paipo, I just put boiled water on the board and bent very hard for like 20 seconds. You want to bend hard but not too much otherwise the board may crack.
For the next boards I didn't bother to bend the nose, I think it is useless most of the time as long as the board is not too thick. Plus the plank has already naturally a rocker most of the time.

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