Nominal measurements on the proofgrade stuff?

Might I please get some rough nominal measurements on the following, when anybody gets a minute or two to measure?

1/4" ply - (got that one from an earlier post .20 - .22 inch)
1/8" ply -
1/4" acrylic -
1/8" acrylic -
any other cool stuff i should know about?

Many thanks! :grin:


A lot of north american sales listings for stuff will announce 1/8" when it is really .118 of an inch, or exactly 3mm thick.

5mm (.208) and 6mm (.236) is called 1/4" for us typically.

Plywood, due to the roughness, can vary in thickness as well. Cast acrylic sheets can also vary in thickness between center and edges, depends on how properly calibrated the creation process is. A digital micrometer is usually necessary to tell, but i think most of us have ran into “that one wrong piece” in our lives

At first i found it frustrating designing in 1/8 inch to find the material isn’t exactly it,(which has led to some mold making problems)but in hindsight, a little sanding in the corners can make it flush.

I have found a bit of mdf in exact 1/8 and 1/4 inches, but it’s really the minority.

I would expect that from what has been said before, this proofgrade stuff will be cream of the crop, made by people who know crafting for people who ARE should be the best quality and reliable thickness we can count on.


Proofgrade materials are still very early in the beta process and will change significantly before we launch them. Any specs would just be interim.


But interesting enough, I usually find 4mm is listed only as .177" with no metric equivalent. Especially in cast acrylic.


Not trying to hold anyone’s feet to the fire - just trying to get some feeling for how much of a variance there is between the woods and the acrylics. I don’t have most of these materials on hand yet.


These are handy for design purposes…thanks! :slight_smile:

Am I correct in assuming that it pretty much never swings the other way? (You’ll never get a slab of acrylic that is more than 1/4 inch thick? Always going to be at listed measurement or potentially undersized?)


Plastics are often specified with a tolerance like 1/4-in thick, +0.020/-0.040" and a piece you get with that spec can be anywhere between 0.270 and 0.210" thick. Worse, an order for two pieces may have one at 0.270" and the other at 0.210". Usually though, a multi-piece order will all be within 0.005" of the same thickness. As @sawa noted, the center of each sheet can be a different thickness than the area near the edges.

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Hmmmn…lovely. :unamused:

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Are you asking for specifics because your designing stuff dependent on material thickness? I was thinking about this the other day and decided I would just make the tabs or joints separate so they can be quickly adjusted quickly without distorting or resizing the entire design. I don’t know if that will work for your designs or for the programs you’re using, but it might be a viable work around until you have the specific material you’ll be cutting in your hands.


Yeah, I was. Not all of my designs are material-width sensitive, but I’m working on one now that has the potential to fall down into little separate planks if it’s not close enough to keep it together with glue or shims.

(And i might have to redesign it somehow.)

It’s making things challenging. (Fun…but challenging.) :smirk:

(I also thought it might be nice to have all the information in one place that we could reference.)