Replies

1. 
   DanMurphy48 | Oct 02, 2012 11:48am | #1

   I've recently had to make 109 cold-molded bends using white oak and epoxy. The formula that gave the most exact spring back calculation for me was; y= x/n(squared). Where y is the amount of spring back, x is amount of deflection (i.e. Radius) and, n is the number of plies. All calculated in inches. So with your glue up, you are looking at 9" spring back on Both sides. Make sure you account for the spring back on the sides and not the axis point! Hope this helps! 

1. 
   csense | Oct 03, 2012 02:52pm | #3

   Bend white oak

   Used titebond III worked well. My sprinmg back for the two boards was 4.5 inches approx. 

1. 
   user-64052 | Oct 03, 2012 03:57pm | #5

   I found a problem

   with delamination using Titebond 3 a few years ago

   ron

2. 
   Westchester | Oct 02, 2012 06:09pm | #2

   Arches

   I'm thinking you need to greatly reduce the thickness of the boards - and use an 8 hour cure epoxy for gluing -

   SA

1. 
   csense | Oct 03, 2012 03:00pm | #4

   Bending white oak

   Used titebond III worked well. My spring back for the two boards was 4.5 inches approx at ends.

   I see your point. I need exact 12' radius. I am thinking to use 1/2 inch boards (3). Will this stop springback or do i need to go to 1/4 inch boards (6).

1. 
   user-64052 | Oct 04, 2012 11:41am | #7

   you are the one asking

   the questions. I just mentioned the problem with titebond 3. mind you are only gluing 2 boards together over a distance and get lots of springback. seems that your success isn't  giving you much, how long have your boards been glued up???  the more plies that you use,   the less spring back that you will get. the more plies that you get, the more open time that you will need for your glue. use epoxy.

   ron

3. 
   Westchester | Oct 03, 2012 09:03pm | #6

   Spring Back

   There is no way to know 100 % if something will work. Yellow glue will creep.  I'd go down to 1/4 in. thick boards and use epoxy.

   SA

4. 
   timh47 | Oct 06, 2012 11:26pm | #8

   Michael Fortune's Recommendation

   At FFW live Michael Fortune recommended Helmitin AT847 white glue for bent laminations. I would use as many laminations as possible. If you can get down to 1/8" that would be very good. Fortune said that with the above glue, which has no "creep", you should  get NO springback. He had a tightly bent example which fitted to it's bending form perfectly. I would always go with the pros!