If you’re seeing that much variation, something is probably mechanically wrong w/ the machine — check the pulley set screws, belt tension, Delrin V wheels — per the machine operating checklist: Machine operating checklist , the basic points of adjustment for a machine are:
- Pulley set screws: http://docs.carbide3d.com/shapeoko-faq/shapeoko-3-how-to-check-the-pulley-set-screws/ — be sure to check all axes/pulleys including Z.
- V wheels / eccentric nuts: Tightening Eccentric Nuts - Carbide 3D
- Belt tension (see the relevant step in your instruction manual, e.g., Getting Started with Carbide Machines) Note that the X-axis motor is held in place on standoffs and if those bolts are loose this can cause belt tension issues. Also, belt tension for the Y-axis stepper motors needs to be even/equivalent on each side — a significant difference can cause skipping on one side eventually resulting in lost steps on both. Measuring belt tension, squaring and calibration
Yes, RPM matters — you should use feeds (selected in Carbide Create) and speeds (applied by the dial setting on the compact trim router used when cutting) — this could also be an issue. Extensive discussion at:
and
One thing I like to do is to adjust the Depth per Pass in Carbide Create so that the final cut of a pocket is a very light cut — say that one wants a 1/2" deep pocket (0.5") and the depth per pass is specified as 1/8" (0.125") — the machine will make 4 passes:
0.5 / 0.125 == 4
If you reduce the depth per pass for that pocket to 0.12", you will instead get 4 full-depth passes, and a finishing pass of 0.02".
To get the same effect around the interior you would inset this pocket to leave a roughing clearance, then only cut to 0.48" deep, then assign a second pocket operation which you cut 0.5" deep in a single pass using the original geometry.
If a Probe operation is off, how it is handled depends on when it is determined:
- if before the cut is begun, re-probe, or manually adjust the zero
- if during a cut, pause, stop, re-initialize, and begin again