bowing plywood

[crs1]

just a quick ? i know i can bend 1/4 inch plywood using steam but is it possible to do the same with 3/4 inch oak plywood? or would it be better to use 1/4 and then cover it with 3/4 inch of fiberglass being i am not going to stain the cabs they are going to be painted.

[MJL21193]

Originally posted by crs1
just a quick ? i know i can bend 1/4 inch plywood using steam but is it possible to do the same with 3/4 inch oak plywood? or would it be better to use 1/4 and then cover it with 3/4 inch of fiberglass being i am not going to stain the cabs they are going to be painted.

Hi,
Fairly tough to bend any 3/4" material. How much of a bend are you looking for?
As any material bends, stresses are set up - on the outside of the bend, you have tension (tendency to tear the material as if to pull it apart). On the inside of the bend you have compression (it wants to crumple like accordion folds)

You could make kerf cuts to get a tight radius, but this can wind up looking "segmented". Another option is to use 3 layers of 1/4" gluing these together. Using hardboard ("Masonite") can be a lot easier.
3/4" of fiberglass sounds like too much work and expense, but if you want an extremely smooth finish, it would pay off in the end.

Good luck.

[jneutron]

I totally agree with John.

Bend and glue 3 or 4 pieces of 1/4 ply. Make a few test pieces first, use radii equal to and less than the desired one, to see how they relax. That way, you do not have to force the final product.

Cheers, John

[pinkmouse]

Thirded.

[crs1]

Originally posted by MJL21193



Hi,
Fairly tough to bend any 3/4" material. How much of a bend are you looking for?
As any material bends, stresses are set up - on the outside of the bend, you have tension (tendency to tear the material as if to pull it apart). On the inside of the bend you have compression (it wants to crumple like accordion folds)

You could make kerf cuts to get a tight radius, but this can wind up looking "segmented". Another option is to use 3 layers of 1/4" gluing these together. Using hardboard ("Masonite") can be a lot easier.
3/4" of fiberglass sounds like too much work and expense, but if you want an extremely smooth finish, it would pay off in the end.

Good luck.

i think i am going more to the fiberglass because i just talked to a good friend of mine and last month he just got a fiberglass spray setup to do boat halls and he said if i install his car stereo he will hook me up if i make the mold and ihave the gel coat so thank you for your help on this matter