Hey Open Builds Community, Question: Does anyone know why we are seeing an X-Axis offset? We are seeing an X-Axis offset while machining along the Y-Axis. We are machining maple wood on a OpenBuilds 1010, and using the OpenBuilds Touch Probe to zero in X,Y & Z. The tool size is correct and verified. Calibration is completed as well (which shouldn't be an issue, because we wouldn't see scaling issued near zero). We are seeing the same issue with several different tools when zeroed the same way. We machined a fixture for the straight wood and clamp into place, so the machine Y-Axis is "straight". Any thoughts? Thanks! Sean
Its not off by much. So here are some things to check. By themselves they may not cause the amount of offset you are seeing, but added up, they can. 1 - Measure the touch plate side with calipers. It should be 10mm. If is not, you can adjust this by selecting Custom Probe in the probe type dropdown. Then click on the gear icon next to it. 2 - Spindle is out of tram. 3 - Tool or collet runout. 4 - When probing for X and Y, its best to use a precision ground dowel. 5 - There is an amount of overtravel in grbl probing. At this time, Control doesnt take that into account. On my machine its consistently .08mm. I've accounted for the this by using the Custom Probe type. Probe offset vs PRB · Issue #246 · OpenBuilds/OpenBuilds-CONTROL
Thanks so much for the helpful feedback! We'll run these all down and report back. Please, others feel free to add ideas. Sean
the tool diameter entered into the probe wizard is used to set the centerline of the tool. thus, if the tool travels along X0 it will cut half the diameter into the stock. Without the Gcode you are running it is hard to say what is happening, really.
Here's the g-code that cut that radiused profile (second picture). It's using a 1/2" ovolo bit from CMT (Ovolo router bits 7/8/927 | Industrial router bits | CMT Orange Tools USA & Canada) We measured the tip diameter as best we could with digital calipers and it's very close to 1/2". We had to increase the tip diameter by 0.040" to get it to cut without that little ledge. I know those tools aren't exactly the nominal dimension, but I have a hard time seeing how it could be that far off. The first picture shows a little gouge in the side of the workpiece. That was made by putting a 1/4" bit in and moving it to -1/8" in X and some arbitrary distance in Y. Then we pushed the workpiece against the fixture, which allowed the bit to cut into the wood. The fixture was cut by machining with the cnc router, then we set X and Y zero with the touch block thing and a piece of wood clamped in the fixture. Just a little more info in case some of that wasn't entirely clear. =)
