Nominal versus Actual thickness

[Minor Project]

I haven't bought my foam yet, but I went to the store to try to figure out if the nominal thickness is the actual thickness. When I measured the edge of a 2" piece of Foamular 250, I found some variability, but they ranged from 1-13/16" to 1-15/16", so I was planning to call it 1-7/8", but I don't know if the edge measurement is the same as the thickness throughout the piece or not. For those of you that have worked with foam before, have you found that that the nominal thickness is the actual thickness or should I plan on something like my edge measurement?
Thanks, Tim

[Redneck Teepee]

Nominal thickness is how the manufacturer identifies shall we say the average thickness of their products. Most manufacture's will give what they call "Mill Tolerance's" which basically means it can be over or under by a few thousand's or so, but will fall within those dimensions. If you want precision in anything you will pay for it.

[ghcoe]

Yes I found out that there is differences in foam thickness. During my build I was going a little nuts at one time with measurements that where not coming out right when I did a cut. I finally figured out it was the foam, it is not consistent in thickness. The largest discretion is the edge on the long side of the foam. if you look at it you will see that it tappers down towards the edge and starts the tapper about 2 inches in from the edge. So one side of a sheet is flat and one side is tapered along the long side 2 inches in. The core portion of the foam seems to stay fairly consistent with the 2 inch measurements.

[Minor Project]

Thanks, very helpful. I will plan on 2", but I will be prepared for some variance.

[GPW]

MP , It’s not really critical with a Foamie ‘ ... Just measure (twice) what you need to and you’ll be fine ...

[KCStudly]

...or sand a little here and there to fair things to your liking. My little oak 1x block with a quarter sheet of sandpaper is a constant companion on my build.

[GPW]

Think of it like a 2” X 4" .... which is Not !!! Plywood is seldom a nominal number...