I was fustrated this last weekend as I was milling a part and it was difficult to get the correct zero point. I useally have not had issues as I am milling larger parts and zero being off 2 to 3 mm is not an issue but this weekend I needed more precision. First method is to replace the bit with a finer pointed bit or a point into the router and use this to set zero – not practical as I had to do 20 parts. Tried this also but the x-carve is not that close when it comes back to the home position (repeatablity was a little off) or if you have minor movement in the placement of the product on the x-carve platform. I decided to print a 3d part on my printer to slip over the bit on the router that came to a point. Did a simple Tinker Cad part see photo. May need to sand the 3d printer part a little as the curl of the point of the PLA on the top not sure you see this on the photo. The part on the right is the printed part with a large raft to support when printing it breaks away and has a hole in the center 2mm that can be easy to drilled out for the bit your using on the router.
I wrote a post about automatic 3-axis zeroing with the Xcarve a long time ago. Just search for it.
Make a bump stop or fixture for repeated location of your material.
the you can use last XY zero for each subsequent part.
If you machine is not consistent going back to XY zero you have mechanical issues that will result in poor accuracy no matter where you start from.
Tighten the ship as someone has recently stated.
- Homing switches! Instant reference system.
If your rail gets bumped while powered off, I dint think even sending it home will resquare the rail. I usually use a set of mdf blocks (exact same length) to bump the left and right rail ends against the front x axis rail mounts and then power on. If you power on after bumping on accident, the left and right ends of the x rail are different distances from home. There is no way for the steppers to know that without a position sensor on every rail. I could be wrong, but don’t see any other way.
Correct, it wont. Consistent homing precision require a consistent machine.
Squaring blocks at power-up then home will solve inconsistent Y-axis.