Replies

1. 
   RickL | May 17, 2004 06:37am | #1

   This was on the Fine Woodworking site a while ago but not anymore apparently. It's an approximation but it's worked for us. Thinner laminates spring back less as well as using a harder glue versus PVA. You can also prebend thin laminates using heat. You might check out how they bend acoustic guitar sides for this. A propane torch inside a piece of pipe and the sides are flexed around the pipe. Pretty simple and low tech. There's also http://www.bendywood.com

   A number of plies of similar

   wood (n) are glued and clamped

   to a curved form, which is shaped to give the lamination a deflection of "x."

   When the clamps are removed, the lamination springs away from the form

   by an amount "y." Exactly how much springback can be predicted with the

   formula y = x/n2.

   The ratio of springback to the original deflection depends only on the number

   of laminations. The ratio does not depend on the properties or thickness of

   the wood or the geometry of the curved form. Thus, for two plies, the

   springback is one-quarter of the initial deflection, or one-ninth for three plies

   and one-sixteenth for four plies.

   -Bill Clayden, Isle of Wight, England.

1. 
   LD | May 17, 2004 02:06pm | #2

   Thanks for your reply.  That will be very helpful.  I guess the best thing to do is some experimenting based on what I'll be using.

   Have you ever used PU glue for a job like this?

   Dave

2. 
   UncleDunc | May 17, 2004 08:00pm | #3

   Click on the Advanced Search button near the top of the left hand frame. Select 'Using the boolean expression:' in the menu above the search text box. Enter

   (laminate OR laminated OR laminations) AND ("spring back" OR springback)

   in the text box. Click the Search button. When I did this just now, it found 40 messages.

   One thing I really like about Google is that the search results come with a URL you can include in a message like this, instead of having to describe how to do the search. Unfortunately, Google doesn't index Knots messages. :-(