So at Z25 it’s perfect. The probe just barely slips right under the end mill. So it may just be the Z movement is slightly over shooting the incremental steps. I’ll have to look into Z adjustment for belt stretch or whatever may be causing it
But also yeah the probe is off at the circle by about 0.3 mm. It’s not a lot, but it’s not a perfect 25 all the way around. The little lip I thought I saw while measuring the 22 mm is just a fillet around the edge that ends before the lip.
I think this confirms that the problem is the probe. Your machine moved back to the exact spot it probed. That’s what you want. When the probe is short, CM tells your controller that its 25mm anyway. This makes the controller “think” it’s 0.3mm higher than it is which makes the cut deeper.
Try this:
Jog to where you’d start your probe.
In the MDI send: G21 (force mm mode) G91 (incremental mode) G38.2Z-50F150 (probe) G0Z2 (retract) G38.2Z-5F45 (slow probe) G10L20Z24.7 (set Z as 24.7mm) G0Z15 (retract) G90 (restore absolute mode)
I mean… from 31 to 25 isn’t a long way to go to become inaccurate so it still could be the Z. I haven’t really used GRBL at all to know what running those codes accomplishes
Just a probe command that uses 24.7mm as the thickness of the probe. It’s a “double-tap” probe to, hopefully, improve accuracy. First two commands don’t cause motion. The g38.2 will probe and stop on contact, then it will lift 2mm and probe again, slowly. On that probe, it will set the Z height at 24.7mm. Retract so you can get the probe out.
Same commands CM uses for a probe (not sure if they double-tap).
That’s all manual. Doesn’t change anything in the way Motion works.
I’d recommend moving to a different sender to anyone that wants to understand what their machine is doing and how it works. Prevents a lot of problems and gives options for solutions when you know why the machine does what it does.
Hmm. I’d prefer as much automation as possible. I don’t want to have to do all that every time I probe. I’d rather just have a probe that works with the automated probing as it’s supposed to. I understand the benefit of knowing what’s happening, but I don’t want it to add any more time to the process if it can be done easier and quicker
CNCjs, UGS, bCNC, and others will allow you to make that a single click operation. Carbide Motion is a black box that you have to blindly trust without knowing what’s going on…unless you dig.
Anyway, I was just offering a suggestion to do a test probe with your short (24.7mm) probe. I would not recommend using CM to type commands like that every time.
If your probe is out of spec, I’m sure C3D will make it right. At least it has a little LED on it!
If you’re looking for an alternative probe solution, this has yet to fail me.
So did you just make a connection from the PCB to the foil and use the same alligator clip grounded to the machine to connect to the end mill? Do you know the pinout of which wire needs to connect to the foil? https://docs.carbide3d.com/assembly/touch-probe/img/CM24_2.JPG
Wait… so I also could use an aluminum wasteboard grounded to the machine, and an alligator clip on the end mill connected to the PCB too right? That would give me Z zero at the wasteboard like I’m wanting (if I used a manual probe command not the Motion set 25 mm parameter)
Oh I see G0Z2 from your original instructions would only retract to be 2 mm over the bed and then slowly probe from 2 mm to 0.
As long as I moved the probe and ground away from the bed when I’m not probing it should be fine to use an aluminum bed correct?
I already have the aluminum extrusions that I planned to use as a baseboard, so it might make the probing easier anyway
So I have to run each line one at a time right?
G21 wait… G91 wait… etc.
You don’t need to wait in between, but they need to be sent separately.
If you’re going this route, move on from Motion.
As far as the aluminum bed being connected to +5V, you’d just have to be sure that it is isolated from the rest of the machine. You don’t want to have some screw holding it in place causing it to be grounded…your probe would always be triggered.
Yeah motion doesn’t even give you confirmation that the command was accepted. I’ll definitely look into one of those other options.
With the probe on aluminum, I can just place the probe on the bed and alligator clip on the end mill when probing, and just remove both when not probing