I’m building a bed (hard maple) and need to laminate 2 80″ arches (circular arcs) with cross section 6/4 ” x 8/4″ about 12″ rise ends to center. I’ll be using 2 big forms/cauls and all my clamps. Four questions: formula for the radius of this circle; how many plies do you advise; what’s the best (low-creep) glue to use; how much springback to allow for? I’d like to use the maple but would use ash if more reliable result.
thank you very much, SS
Replies
6/4 is 1-1/4" finished. So five 1/4" laminations would be good.
I don't worry about spring back. I cut the mating pieces to match.
PVA glue works fine for me.
S',
For your math question: http://www.math.com/tables/geometry/circles.htm
When laminate bending, the thinner the ply's, the more resistant the piece will be to spring back. In other words, it's better to have more thinner ply's than fewer thick ones.
Because you're using maple, it's important to use the right adhesive to prevent dark glue lines between the plys. Epoxy and resin glues will give you a rock solid bond without creep. White and yellow glues are prone to some creep.
When I do a curved/bent lamination out of maple, I will use something like Unibond 800 in a light colored wood formula. (It comes in multiple shades to help match wood color to avoid visible glue lines). http://www.vacupress.com/veneerglue.htm
I used Unibond for this cradle prototype that I designed/built (see enclosed photo). The ply's are 1/8" thick for the legs, and 3/32" thick for the slats. Each slat runs from the top edge of one side, down and across the bottom, and up the other side.
If you have any questions, please feel free to ask.
Dan Kornfeld, Owner/President - Odyssey Wood Design, Inc.
Edited 10/21/2005 11:18 pm ET by jackiechan
Just me so... I have made several bows of laminated ash and hickory (light colors sort of).. I used PROBOND Polyurethane glue 'Elmers'..
Zero creep.. None are stained and just rubbed with oil.. You know it's laminated because of the different types of wood but no visible glue line..
However with my laminations I take special care that the entire lengths are FLAT before I do any forming and gluing...
Bottle I just looked at says stainable..?
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