Inaccurate cutttings

[Joser (Jose R. Soto-Canino)]

Hello Guru’s, I am in the process of cutting some ovals. The issue I have is that the cut starts what appears to be normal but on the second pass it cuts into the oval on one side and ruins the piece. I have the material (pvc) screwed down into the wasteboard so its not moving. I also tried cutting a different silhouette and it did the same thing.??? any ideas? I tightened down all eccentric jogged the machine through all it’s motions. It’s an XL. Thanks, Joser

[WillAdams (William Adams (Carbide 3D))]

This is likely a mechanical problem: https://wiki.shapeoko.com/index.php/FAQ#Mechanical

It may be a matter of toolpaths and feeds and speeds — slotting is hard, see:

Adding geometry to cut as a pocket with a finishing pass

One technique which is often suggested to avoid slotting is to add geometry around a part which one wishes to cut out and cut as a pocket down to tab depth — here’s one technique for that. In this case, the project is a bevel gauge which will be cut out of 0.0625" (~1.5mm) thick aluminum: [bevelgauge] Due to the narrowness of the angles, an 0.03125" endmill has to be used, so after importing and scaling the file (we will be cutting out one which is 3") we select the perimeter and offset it tw…