Touch Probe Z axis not calibrated correctly

(Kaleb Israel) #22

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.

(Neil Ferreri) #23

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)

(Kaleb Israel) #24

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

(Neil Ferreri) #25

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).

(Kaleb Israel) #26

So does that change the command to a double tap parmanately? Or do I have to manually put all that in every town I want to probe?

(Neil Ferreri) #27

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.

(Kaleb Israel) #28

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

(Neil Ferreri) #29

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.

(Kaleb Israel) #30

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?

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)

(Dan Nelson) #31

Triquetra Toolbox software works with Carbide Motion and allows you to define touch plate dimensions.

I have both the C3D probe and the Triquetra probe. Slightly different work flow using the toolbox software, but it works well.

I believe you can buy the software by itself. I can’t say for sure since I got mine for being a beta tester.


(Neil Ferreri) #32

All the commands are the same. Doesn’t matter if it’s Carbide Motion or manual or triquetra.

Save yourself the trouble and put your probe on top of the foil (out of the way). You get to keep the fancy LED indicator too.

(Kaleb Israel) #33

huh? If I use the Z probe in Motion it will think the foil is 25 mm thick.

Yeah I could use the probe on an aluminum bed and just put the carbide touch probe out of the way and Z zero on the aluminum bed too.

I still would like to confirm my Z is moving up and down at the right increments

(Neil Ferreri) #34

Yes, just clarifying that they all use the same commands, Motion just has a hard coded probe thickness.

Always a good idea, but it’s the cause for your probe issues.

(Kaleb Israel) #35

Yeah if I was to do it manually, I could use
to set Z zero right at the aluminum bed right?

“but it’s the cause for your probe issues”
The Z calibration is the cause for my probe issues?

(Neil Ferreri) #36

Oops…NOT the cause.

That’ll only probe down 5mm very slowly.
5 is the distance, 45 is the feedrate.

Careful using an aluminum bed. The probe is at 5v. You don’t want to create a short, making the probe not work.

(Kaleb Israel) #37

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.

(Neil Ferreri) #38

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.

(Kaleb Israel) #39

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

(mikep) #40

This isn’t super reliable. I’ve got an aluminum bed on top of a mdf bed, and I still get ground shorts on the probe.

(Vince) #41

I spaced my brains from the frame with double sided tape, problem solved for me