So I successfully created a reproduction artifact (see Archeo-build in Builds and Built) but because of the irregular nature of the artifact, I did not notice that my dimensions are off until cutting a few squares. In AutoCAD I created 50 mm and 100 mm squares and then used EstlCam to cut them out of 1/4-inch plywood. When finished, both squares are square (exactly same diagonals within 0.1-0.2 mm measured with some plastic digital calipers). The smaller one was only very slightly off. However, the larger one (100 mm) was off by 2-2.3 mm in both x and y axes. The x and y dimensions were 97.5-98 mm on a side with equal diagonals with acceptable error (0.1-0.2mm). So, over 100 mm, I lost 2 mm in each direction. Angles are 90 degrees at corners and edges of cuts appear to be perpendicular/vertical. I’ve repeated the larger square 3 times with similar results. I’m going to try two larger squares (200mm and 300mm) tomorrow
I was using a 1/8" 2 flute bit on Dewalt 660W with I believe 20 mm/sec feed rate and 1mm DOC on 1/4-plywood. I was getting nice chips and the spindle did not seem to be straining against the wood (too fast) or heating up and burning (too slow).
Any ideas or help would be greatly appreciated. I want to try to solve the dimensional inaccuracy so I can cut parts for the MP3DP.