nsabean.blogg.se - Bidule 58

Torsion boxes and box beams are remarkably stiff structures. You are better off to go with a single thickness of ply and add an 1 1/2" hardwood drop edge. Only half the ply's are orienter across the grain. VC plywood isn't designed to resist bending. With the compression skin you stiffen it up considerably. Try doing this with 2 layers off 3/4 VC ply and this picture has the tension skin on. Robert.A torsion box is considerably stiffer and flatter than full thickness laminated plywood. The only benefit I see is the lightness aspect if this is an issue. A shelf is not in torsion, just simple span bending, the double 3/4" will be stronger, and no chance of being punctured some day in the future. Also the time to build the torsion boxes compared to simply gluing the two 3/4" panels together is really tough to justify in time.

First off, I have not found 1/4" material to be "a whole lot" cheaper than 3/4" since you are mostly paying for the face veneer. I am going to say to Dave - you may want to rethink the torsion box.

If shelf depth is doubled, deflection is cut in half.

If shelf thickness is doubled, deflection is reduced to one-eighth.

If shelf span is doubled, deflection is eight times greater.

If shelf span is increased by one-fourth, deflection doubles.

If shelf span is reduced by one-fifth, stiffness is roughly doubled (deflection is halved).

They have some nice tips at bottom of the page Machaely, this is a good site, definitely bookmarked. I will put a face frame to hide the ply on the sides. The top and bottom shelf will be fixed but the four middle ones will be adjustable. I usually use 1/4" plywood for the back so dadoes/nails are not an option. I will put a solid wood edge band to hide the exposed edge on the shelf. This is for a Bookcase that i want to put in my living room so yes the look is really important to me, this is why i want to double. I don't really care about money saving, at around 40$ per sheet of plywood no big deal for me.

Hey thanks Birchwoodguy, i was looking on how to do it here. Re: How would you double plywood for stong shelves ?