Not sure if this has been mentioned before specifically regarding the proof grade medium clear acrylic. With the 2 sheets that were sent out with my GF there is a .007" difference between the 2 sheets.
I guess in hind sight I will have to measure every since piece and design a new cut file for every singe piece. Just wish there was more consistency in the product. i went through and designed and tested on one sheet and cut out a few finished pieces with an accurate friction fit and then cut a few more on the next sheet and they just fell apart. luckily I only wasted ~1/3 of the sheet in this error.
Sadly that’s a known issue with the manufacture of acrylic (not just , all acrylic) . Somewhere in here the “allowable” difference is listed, but I couldn’t find that one. You’d do better designing for the thick end and possibly using glue
as @deirdrebeth mentioned, this is a cast acrylic issue, not just PG. extruded can be made to a more consistent thickness (although still not perfect) because of how it’s made (extrusion).
from this site, they mention that cast acrylic sheets tend to have a greater variance on thickness tolerance (as much as + / – 30% on thickness). while extruded sheets have a better tolerance on thickness, typically + or – 10%.
0.007 inches is one kerf width. I am surprised you have only that much variation. I expect, and design my files to account for, up to 0.5 mm or about 0.020, thickness variation, then measure and mark each corner of the sheet when it comes in and adjust for that thickness. I have seen that much variation in a single sheet from some providers.
Sorry you had to discover the tolerances allowed in manufacturing at the cost of material. I learned from the .22"" chemcast I get a lot of. I had a project that was just perfect. Went back to do it again and nothing fit. Started measuring all around the perimeters of several pieces and that’s when I discovered it.
Thx for all the useful information. It will help out greatly in the future, first time using acrylic and never crossed my mind that there would be a variation in the thickness like that.
Except for acrylic joints It’s not really easy to sand a joint looser because it’s often when it breaks you find out that it’s just not going to fit. Weld-on has a few different solvent thicknesses that will allow you to do some small gap-filling and it melts the acrylic together so it’s way stronger than just glue.
I use a file for acrylic. You can tell before you break it if the acrylic is too tight. A good acrylic joint should just slide together with a small amount of force. If you have to push hard enough to risk breaking, the joint is too tight and you will risk cracking under the sustained load over time.
Thank you so much for the discussion everyone and @deirdrebeth for your answer. It looks like the conversation has wound down. I am going close this topic out, if you have additional questions please open a new thread.
, all acrylic) . Somewhere in here the “allowable” difference is listed, but I couldn’t find that one. You’d do better designing for the thick end and possibly using glue
It’s not really easy to sand a joint looser because it’s often when it breaks you find out that it’s just not going to fit. Weld-on has a few different solvent thicknesses that will allow you to do some small gap-filling and it melts the acrylic together so it’s way stronger than just glue.