PLEASE may I get a quick plywood size clarification?

[Mark Rios]

I'm going out to the plywood distributor to get some 1/4" oak plywood for my cabinet job. They close at noon today. The last time I got (I thought) 1/4" ply from the Borg, it turned out to be only 3/16" thick? If I get 1/4" ply from a "real" plywood distributor, should it be a full 1/4" thick? Or is it undersized like all other plywood?

I'm asking because the Freud rail and stile bit set that I am using seems (by my measurement) to cut a full 1/4" groove for the panel. If the plywood is normally undersized, how do I fill the extra 1/16" in the groove?


Thank you very much for your information.

[Cecil Arnold]

Mark, how about that depends for an answer. There seems to be no set standard on plywood. Some is very close and other is not. If you want to know, then I suggest you take a dial caliper with you. On the other hand, you can adjust the Freud S&R by removing the washers if necessary. I know it's a PITA, but unfortunately that's the world of global trade we now find ourselves living in.

[Paul B. Cresti]

No all lumber is nominal size. The gap you have will be normal. You can either face the substrate (in this case plywood) with a good veneer or make the panels out of solid wood and allow for expansion/contraction. You can also use a filler type material in the length/width dimension of the panels to keep them from rattling around but allow for exp/contr

[Bart Leetch]

Most plywood is slightly under the nominal advertised size now days. There is a special set of bits made just for plywood that meets this requirement.

[Mark Rios]

First, thank you very much for the quick reply.

Paul, I'm not even close to thinking about being as experienced as you are and veneering isn't in my range yet. Gluing up the panels would work but I only have a 13" planer (DW735) so wouldn't be able to thickness the larger doors. I assume you are referring to something like space balls?


And Cecil, my set is a 99-263 rail and stile set. It's just a simple beaded roundover. The groove cutter part of the bit isn't adjustable, it's just one cutter with a big 1/4" piece of carbide on the outside (two really, one on each side of the bit, of course).


But I will take my calipers with me and see if the mabe have different grades of oak ply to choose from and maybe one of their thicknesses will work.

Thanks again to all of you for your quick replies.

[Frank Pellow]

I doubt it. It's a very long time since I purchased 1/4" plywood that was as thick as 1/4" (and I buy most of my wood from "real" lumberyards). :(

[Steve Clardy]

The only 1/4 ply available that is 1/4", that I know of, is mdf faced both sides with veener.
Most the others are 7/32

[Phil Phelps]

Most plywood is slightly under the nominal advertised size now days. There is a special set of bits made just for plywood that meets this requirement.
I acutually found a maple/birch plywood at HD, for $29.99, that is .75 thick. Bought twenty sheets, I wasn't gonna' let this get by. The deal is, the manufacturer will label the material by mm and not inches, which is what we should be using. They cut the size, charge you a hair less, and most of the stupid public is happy, happy. I'm tired of these schemes. Be a smart consumer. It isn't just in lumber, you know.

[Mark Rios]

Thanks again for all the info and help.

I found that the better grades of ply are usually thicker than the imports. Also, this particular distributor carries some material (all mdf core) in 5.2 mm (red oak 1-side), 6.0 mm (red oak 2-side), and 1/4" (white oak 2-side) thicknesses. Hmmmm.......not sure why the differences are there (other than a manufacturer preference?) but I guess that as long as they are the same per job it just takes figuring the one time.

Is the only difference between mdf core and regular ply core the tendancy to stay flat and consistant thickness or is there some other differences?


Thanks very much again.

[Steve Clardy]

Mdf core won't wrinkle up, warp like veener core.
I usually do use use anything mdf, but got some oak mdf core in by mistake, for flat panel doors. Had a time crunch, and had to use it.
Actually kinda liked it for the flatness.

[Jim Becker]

My friend Russ uses MDF core for nearly all his cabinetry work at this point, both hired out and personal projects. (He recently finished his kitchen identical to the prototype piece I posted about quite some time ago) I got some of it from him when I was doing my mantel project and was very impressed. I'd use it again, despite the weight, just due to the fact that it's true in size and available with just about any species and "cut/figure" you want, including quarter-sawn.