Presumably, the various probe files created by Openbuilds Control when the USB drive is imaged include variables that are replaced at execution time. The variables include <xoffset>, <yoffset>, and <zoffset>. Based on the G-code commands included in the D:\PROBES\PROBE[X][Y][Z].PRB files and the fact that the control panel's probe menu includes a selection for the router bit diameter, it would appear that the <xoffset> and <yoffset> would be replaced with 1/2 the bit diameter while <zoffset> would be replaced with the probe plate thickness. The latter should be known at the time the USB drive is imaged as the type of probe is selectable/customizable. Hence, it's a bit of a mystery why <zoffset> still appears in the probing files. That being said, probing with the stock files results in the following issues. 1. When probing for Z or XYZ, the Z-axis zero point is 2mm above the work surface. The Openbuilds XYZ probe I'm using has a thickness of 12mm. To circumvent this issue, I replaced G10 P0 L20 Z<zoffset> with G10 P0 L20 Z12 in PROBEZ.PRB and PROBEXYZ.PRB. 2. When probing for X and/or Y (i.e. PROBE X, or PROBE Y, or PROBE XYZ), the XY plane zero position is set to the position the tip was at when the probe operation was initiated. It would appear that the G-code commands to set the X and Y positions (i.e. G10 P0 L20 X-<xoffset>) are being ignored and the X and Y zero positions are left unchanged from the G10 command at the start of the probe file (i.e. G10 P0 L20 X0 Y0 Z0) before any probing is performed. To circumvented this issue, I replaced the X and Y position commands wherever they appeared with the following respectively. G10 P0 L20 X0 G10 P0 L20 Y0 While this doesn't take into account the width of the bit, it does leave the zero point close to the edge of the material. To compensate, I position the XYZ probe plate inside of the material corner by approximately the width of the selected bit.
<xoffset> and <yoffset> gets replaced by Interface on every run with the calculated offset of half endmill diameter plus the offset of the shoulders of the OpenBuilds XYZ Probe Plus. Same for <zoffset> - gets replaced by the thickness of the OpenBuilds XYZ Probe Plus. Interface only supports our probe at this time Of course one can edit the Macro files on the USB and do clever things like add an extra G10L20 to compensate from difference in offsets if you are not using our probe - let it do it as if its our probe, then add a G10L20 to change the coordinates to + or - the difference in shoulder/thicknesses. That way the <×offsets> still exist and allow the Interface UI's Endmill Diameter to be used
I am using the Openbuilds XYZ probe and the CNC touch interface loaded with version 1.52. An XYZ probe operation leaves XY zero at the center of the probe plate's hole and the Z zero position is 2mm above the work surface. While the XY position could be compensated for by positioning the probe plate horizontally so the center of its hole is at the lower left corner of the material. However, the Z positioning is incorrect.
If its our probe, it should all work as intended. Check Z shaft coupler grub screws - perhaps your Z axis is slipping a bit. Also check your Calibration
Yes, that's correct. Probing sets the center of the bit to 0. So the bit should be in the center of the plate hole because thats where the lower left corner of the stock (X0Y0) is.
I stand corrected! 1. Double-checking my calibration, I found I had the wrong numbers. 2. I was using the XYZ probe plate wrong. I didn't realize the plate had to be positioned so the left and bottom edges hang over the edge of the material. It's brilliant idea that makes perfect sense. With these two corrections, the resulting zero position is correct... almost. Eyeballing the tip of the 1/8" router bit (yes, I selected the correct router diameter in the probe menu), it appears that the bit is positioned so its edge is aligned with the material edges instead of its center/tip being over the material corner. If I select a 1/4" bit diameter with the 1/8" bit I'm using, the center of the bit is then positioned over the corner of the material. Perhaps I'm still not doing it correctly but at least I'm getting closer.
Sometimes that will happen depending on where the flutes are when it touches the probe plate. Any chase you have a piece rod of a common size? You can use that instead of the bit so we know its not a flute issue. And honestly, if you want more precision, you should always use a precision ground rod to do your X and Y. Then insert the bit to do your Z.
Thanks. I definitely don't need that kind of precision but your suggestions is an excellent one if I did.
