I've successfully converted my CNC to the TinyG board.

I’ve successfully converted my CNC to the TinyG board. I think I have everything running well, but I have some questions on auto-leveling for pcbs.

The auto-level widget seems to only be metric. If I switch to inches, the units stay at mm, and the values do not change. Does the auto-level widget work in inches, or should I use mm, even if my gcode is in inches?

I tested the auto-level circuit a couple of times, and it seemed to work - the router went down, and when I touched the PCB to the bit, it stopped. I then set up a test board, and established zero at the lower left of the PCB. When I start an auto-level now, the router goes up slowly - not down. I am wondering if this is somehow related to me reversing the polarity of the Z axis inside TinyG versus swapping the wires. When I jog using the controls, the Z is moving correctly.

Finally - is there any provision for using a leveling block? With my old controller, I like to auto-level when I am doing fine engraving with a V-bit on wood. I have a level block that is .45 thick. If I set the block on the wood, and auto-level, the software knows to set the Z axis zero at -.45" from the zero height point.


Yes, Auto Level is only in mm. Would love some help from the community if you want to add inches.

On the auto-level with you saying the router goes up, you do need to raise the endmill up a bit like 1 or 2mm before starting auto-level so it can travel downward or it sort of triggers a safety setting. Maybe that’s the issue.

There is a Touch Plate and Super Touch Plate widget for doing the levelling block.

Thanks John, I’ll take a look at it, and see if it is within my abilities to implement. I would love to contribute. For now, I’ll switch to mm for PCBs.

A somewhat more general comment about mm vs inch- tinyG does all its internal computation in mm. It accommodates inch by converting on the fly. The microcontroller does 8 bit math and there some instances where accumulated loss of precision causes tinyG to crash - you will see threads from time to time referring to “The ARC problem”, specifically were gCode has G2 and G3 short arcs that are very slight deviations straight lines (G1 moves) and thus have very large I and J directives, they are segments on really large spheres. A common recommendation is to switch to mm gCode , which often helps by avoiding the conversion math. So, if it really does not matter , use mm gCode.