Steam Bending after Gluing?
Gluing boards before bending is not practical, for various reasons. October 13, 2010
Question
I'm making some bowed drawer faces out of quartersawn white oak. Given the friendliness of the material towards steam bending I was going to try that rather than bent lamination but I need more width than the boards I've got - 8" boards, 9-10" fronts. Has anybody tried edge joining boards before bending? Has anyone used urea-formaldehyde glue? I could also bend them and then join them together to get my widths. Does anyone have some knowledge on this?
Forum Responses
(Adhesive Forum)
From contributor F:
I don't think the glue joint will hold up during the steaming and bending no matter what glue you use - heat, moisture, and stress. It will be severely compromised at best. If you’re making no more than a half dozen drawer fronts you could do the steam method but with spring back, timing, and heating you'll do six before you get the details and procedure working consistently. The wide resawn glue up is more dependable with very good results. Use an odd number of plies for a stable curved glue up.
From Gene Wengert, forum technical advisor:
I agree with Contributor F and add that sometimes a piece will crack. That piece is tossed away. If you had them glued, you would have to throw the entire panel.
From contributor Z:
Kiln dried wood does not steam bend very well. You should try to work with partially air dried material (between 15% to 28% MC). The glue joint won't survive the steam or the bend. You could bend your individual planks, dry them, surface the edge, and then glue them up - ideally with a non-creep glue (like the UF you mentioned). Don't forget that if you are steam bending, except for very gentle curves, you will need a steel backing strap to drive the compression to the inside of the curve, which prevents stretching the wood on the outside of the curve. The stretching causes cracks and splits, usually where grain runs out. Hardwood will compress well, but doesn't stretch, unless it's engineered to do so.
