Now that my spoilboard is good and flat, I figured it was time to get off my butt with the touch plate replacement.
I’ve been setting most of my jobs from the lower bottom left corner, anyway, so I put a momentary switch in a little case I made on the printer.
Zeroed off the spoilboard with the tiny touch plate, ram a g32 on the switch, did the arithmetic and used that to figure out the trigger height (which I wrote on the spoilboard because I know I’m gonna forget and then delete my macro or something).
Also helps that I just learned about g53. For everyone who didn’t know, that moves to the machine coordinate, say g53 x1y12, without disturbing the work coordinate. Maybe somebody can clue me in if I’m off, but I think - 54,g55,etc are all offsets of the g53 space. So really, I’m just telling it to move in THAT space for one line of code. That means I get to set my origin wherever I need it, and when the gcode pauses to change tools, I can do that and run a macro that sends me over to the switch (which never moves).
Worked pretty well on a job I ran tonight.
Very cool. I’ve considered this approach (i.e. switch instead of a touch plate that needs to be attached to the bit using a clip), but I’ve been concerned about accuracy/repeatability. Carbide 3D sells their BitSetter (which I think is mostly an accurate switch) for $120, so I assumed that getting high accuracy from a momentary switch is expensive. Maybe you would run a test sequence a bunch of times with your zeroing against the switch and then moving some set distance above the spoil and verifying that distance with a feeler gauge.
As for G53/G54, typically you would zero your machine G53 and then put your machine in G54 for setting the home of the work piece and cutting.
I suspect cncjs does this for me, because it keeps two sets of coordinates. That means I’m probably not far off with the model of this I have in my head. Thanks.
As for the accuracy, I suspect the switch is more accurate than I am. After all, we use cheap switches for the dual endstops. Maybe I could tape the tiny touch plate down, and using the same idea touch off the switch to zero, then touch off the plate without zeroing and do the arithmetic. Make a few runs like that and see what I see.