I bought some plywood for my projector at the home depot and cut them into the right sized pieces, but I noticed that they are sort of curved. In order to make a box with no light seals, I am going to need straighter pieces. Is there some way I can use pressure or soaking to make the pieces perfectly straight?

Nick

I built a few skateboard decks like that.I just steamed the plywood for an hour and shaped them in a press until they dried.It can swell the wood a little,though.If you have access to a good smooth concrete slab then you might be able to soak the wood and flatten it with concrete blocks.Make sure the bow of the wood is up and put the blocks in he middle of the bow until it flattens out.Then just let it dry for a few days like that and remove the blocks.

Another sugestion when you put the pieces together if you screw the pieces it will most likely straighten out

Sounds like maybe Home Depot screwed HIM!

Seriously though, what thickness and number of plies are we talkin' here? 3/4" stuff will be nearly impossible to truly straighten unless you're talking a rather long, plank-like piece. Did you buy 4x4 foot or 4x8 foot sheets? Were they perfectly planar when you bought them?

Like magel said - you can straighten it out during assembly by creatively arranging the pieces so the bows correct each other.

Quality, cabinet grade plywood shouldn't bow appreciably when you cut it but the thinner stuff will be more likely to have some internal stresses that show up as some bowing after you cut it.

1/2" and thicker stuff should remain quite straight after cutting.

well..one thing I learned is that you need to store it on a flat surface, not leaning against something...sounds simple I know but all my pieces were nice and straight when i broght them home from home depot(I had them cut them) but after I got back to them about a week later they were really warped..ya gotta remember some of us have never even seen a saw till now.....(ps: they were 3/4" plywood, sanded on one side... really nice looking stuff too...sigh)

Ouch! Yeah, it's the simple stuff that gets ya. I feel like a total moron about several projector-related things. Like ya said - best stored flat either horizontally or even better vertically with no lean. Bringing a sheet from a controlled environment and leaning it in a moist basement or garage - especially against a moist wall - can reek havoc with a straight sheet of ply. And IT AIN'T CHEAP!!!

Try dampening the convex side with some water. You could even expose the other side to the sun at the same time. Once it has straightened out put something heavy on top and allow it to dry.

DJ

well, after trying to screw it together to straigten it out I finally went to menards and they had some "master craft" #2 grade(some knots) 1" thick pine, 16x36 and 18x36 which was not bad in price(about 30$ altogether) and just about the right size for my 17" vertical, I came home, cut it to size and screwed it together right away , I'll use the plywood for a garden box where it won't matter much if its warped....

A common misconception about working with wood is that it will be straight and true when you use it. Experience, I'm affraid teaches otherwise.

The trick to your situation is this--make the curves cancel each other out when you screw it together. As you join two sides, start at the end and work your way along, constanly adjusting the positions of the pieces as you add each additional screw. It's really not difficult, it just takes patience. And maybe another set of hands.

Unless you want to go back and get cabinet-grade ply. But even then you can get the same problems.

Wood is flexible--use it to your advantage.

Oh man, that's like a Zen Master comment. You should have added "grasshopper" to the end. In all seriousness though - great advice!

...Grasshopper.

LOL!

Words of wisdom, guys. Thanks for the help. I will try to make the curves cancel each other out using screws etc. We'll see how it turns out...

Anyways, it was a 4 by 8 sheet I bought at the store. I dont think it was too warped when I bought it, maybe it just wasn't obvious to me at the time.

Nick

Just a word of warning as those laminated boards can seperate when exposed to too much heat that leads to more drying and shrinkage. So do a good job with flashing within your light engine.

thanks for the warning, hadn't even considered that aspect yet...will do... when you put in flashing, should you screw it right to the wood or would a little spacer be better, say 1/4" or a half inch???

I would suggest an air gap.

Good news guys. Through some carefully placed screws, I have successfully made my box. The one problem area is the door on the side. That piece was somewhat warped, so I am using a hasp to force it flat on the other side. There are still some gaps, but I am going to light-seal it using that material they use to seal doors. Not sure what it's called.

Thanks for all the help,
Nick