Thread: Flattening Plywood?

I don't think you will ever get them flat unless you fix them onto a frame. (Which is not what you have in mind). I would use MDF for templates. It will stay flat but it will be a little softer than the ply and depending on how you will use them as templates, may wear a bit.

Just as a warning to others when cutting pine ply, the tensions that are in the sheet (which makes the sheet not flat) can jam a saw blade in the cut. I have had jams while using a large panel saw....it wasn't pleasant

Great price. I thought warped ply was the norm at Bunnies

what kind of templates are you looking to make? router templates? tracing templates? chair component templates etc? often when you cut the board up into what ends up being fairly thin strips, the ply becomes somewhat flexible and conforms to your will with little persuasion.

The short answer is you can't

Originally Posted by Kuffy

what kind of templates are you looking to make? router templates? tracing templates? chair component templates etc? often when you cut the board up into what ends up being fairly thin strips, the ply becomes somewhat flexible and conforms to your will with little persuasion.

Both router and tracing templates for a cot similar to what you've made and other 'things' .

Originally Posted by elanjacobs

The short answer is you can't

So effectively, what you are really saying is that it is best to avoid any ply that is bowed and bent from the supplier/retailer.

At 2bux a piece, you could throw half of it out and still be in front. I would use it without hesitation. Just design the templates so that the concave side is face down.

Try cutting in half, then glueing together face to face clamped down to a strong flat surface (bench). You will end up with twice the thickness, but it may be flat.

Regards
Keith

One of the things about plywood is that the sheets that make up the ply are glued once taken from the log. I can not see how this could be flatten if it was bowed as each sheet is glued together and it would most likely had bowed at the time of glue up.

Personally I think cutting them so that you can salvage as much of the pieces that are flat.

Broken record but you can't. However as you are making templates, they will be clamped to the job anyway so will flatten as you clamp. Best you clamp to a flat table first to draw the template then cut out.

ps. If u look up Bunnings in the dictionary it's meaning in Swahili is - bent timber.

Originally Posted by cava

So effectively, what you are really saying is that it is best to avoid any ply that is bowed and bent from the supplier/retailer.

Yep. Even the super expensive Hoop Pine stuff isn't always flat. Hardwood ply seems to be better overall for flatness, but I think it's all imported

Hi I note that several responses mention the ply is to be used for templates. On this subject i offer a little workshop tip i have used for years that allows for the making of very accurate templates be they for dovetail joints ,chair pieces,radius gauges or whatever. For printing by the lithographic process sheets of thin zinc plate are used and when the printing run is finished they are normally sent to the recycle bin. They are about 500 x 500 mm normally and most printers will give you some for free I normally spray or wipe on one coat of engineers blue before using for clarity . To make your template use a sharp scalpel knife and dividers and score into the sheet the desired shape . By WIGGELING for the want of words along any line of the template and it can be broken out female or male as required. Is also easy to cut with scissors.An accurate radius gauge takes but a few seconds to make. Also very handy for setting out dovetails or finger joints.The uses are endless when an accurate template is required.

Originally Posted by elanjacobs

The short answer is you can't

And the thickness also makes no difference, although it does to the actual severity of warping. I have a piece of 25mm thick ply roughly 2'x1' by and it's warped.

Have you tried hitting it with a hammer?

If it still won't flatten, you could get a mate to hold it down while in the sun (so it's warm!), then hit it with a hammer.

If it doesn't flatten out, try hitting the other side.