>>965239
I thought that was why jigsaws were made of MDF: it doesn't have a grain, so it can't warp along the grain it doesn't have.

>>965239
yah plywood is not the way to go.
plywood warps. by its very nature. it's unsealed laminated slices of wood. the different grains of each ply will expand and contract differently. not to mention different sides will be exposed to a humidity differential. you CAN straighten plywood though. it will just warp again though.

http://theplywood.com/flattening-warped

>>965240
MDF contains glue and since it's for kids I can't use that. >>965247
What do you guys suggest that will be both cheap, relatively sturdy, easy to laser on and usable for kids toy?

>>965239
>this may or may not work, I've only seen it done once
go to an equipment or tool rental place and see if you can get a steam blasting tool(blasts really high heat high pressure steam for cleaning things)

get a bunch of flat bottomed paving bricks(heavier is better, flat bottoms are also preferred) wrap them 3-6 times in plastic bags so they don't scratch the wood. get at least enough to cover all the warped areas plus a little bit more.

find a place to do this with a smooth, flat, floor and appropriate drainage. sweep meticulously and clean any stains on the ground where you'll be working.

now place the best looking side of the plywood down on the floor. if the steam machine you got has a selector for it you want the ABSOLUTE LOWEST ratio of hot water to steam. blast the piece of plywood really hard all over for several minutes, it'll soften a lot. once it's softened place the bagged weights on the areas that are warped upwards. this may cause other areas to warp upwards and you'll need to weigh these down as well. allow the whole arrangement to sit until dry

>>965254
>MDF contains glue and since it's for kids I can't use that.

Quick question for you, what do you think holds the layers of wood in plywood together?

MDF is fine.

>>966431
>MDF is fine.
usually a coat of paint stops the deadly poison

>>965254

Yep, plywood has glue too. And there's nothing dangerous about "glue". Kids eat white glue all the fucking time. Better to check and see what type of glue is used in ply vs mdf rather than assume it's dangerous.

>>966464
Most glues used are totally inert once cured.

>>965240
>MDF
It's thick cardboard. But hey, wood pulp is wood pulp I guess.
>it doesn't have a grain, so it can't warp along the grain it doesn't have.
It really has more to do with cost, and the fact that modern puzzles are die-cut. Die-cut wood splits like a motherfucker, but die-cut paperboard or MDF doesn't.

But since OP is using a laser, he can use all kinds of different materials. Plywood would work fine, and he could even make a puzzle out of acrylic if he wants to.

>>966370
This is probably the best advice for removing warp from plywood.

>>966488
>This is probably the best advice for removing warp from plywood.
it's just such a damn shame it's so cost and labor intensive...

>>965239
Save yourself the headache and just buy better material. The time you waste trying to fix shit wood isn't worth the $10/sheet you'll save just not buying shit wood in the first place.

Your effort will be better spent finding a different supplier with an appropriate product.

... and there is nothing wrong with MDF or HDF. Even cardboard has glue in it. If this is for toddlers that can't stop sticking things in their mouth you could try acrylic or solid hardwood instead, though those will be considerably more expensive.

>>965239
you don't use hardware store plywood for lasercutting.

>>966675
sometimes thats all you got man, makes good sample pieces for testing small scale versions of larger things.