Repetier touch plate help

Mostly Printed CNC - MPCNC Troubleshooting
1

I’m trying to set up a touch plate, and I’m running a custom scrip but it’s zeroing at the 5mm above the touch plate. the script I’m running is…

G28 Z ; Home Z
G92 Z0.5 ; Account for touch plate thickness
G0 Z5 F480 ; Lift the bit off the touch plate

I am using a SKR Pro 1.2 and tft screen, pre flashed from the shop. I’ve attached a GIF of it in operation, thanks

20230725_174858

2

Your touch plate script is working correctly. Repetier-Host can get out of sync with the actual position reported by Marlin. I cannot pause your video to see if that is the case in this situation. The touch plate g-code code you list above leaves the tip of the bit a Z=5, so the tip of the bit is 5mm above the Z=0 (top of the stock).

In terms of cutting, you have some choices. If you are having Repetier-Host or your CAM (EstlCAM?) insert start code, it is common to have a G92 X0 Y0 Z0. That will not work with your touch plate g-code. The G92 will lock in the current position (Z=5) as the Z=0 position. The most common choices to fix this problem are:

  1. don’t put a G92 in the start code or at least one that sets the Z axes. This is my choice. The issue is that, if you don’t use a touch plate to set up a job, you must remember to set the Z=0 correctly before running your script.
  2. Extend your touch plate script so that the bit is at Z=0 when you start your job. For example, you could add these two lines to the end of your touch plate script:
M0 S3 Remove the touch plate
G0 Z0 F400

This code will give you 3 seconds (S3) to remove the touch plate before lowering the tip of the bit to Z=0. The only issue is that, if you don’t remove the plate, your bit will drive into the touch plate. I’ve had this happen to me (for other reasons), and the touch plate was fine, but your milage may vary.

3

I guess I didn’t really explain that correct, after the script it will move down the 5mm, but Z0 is still at the top surface of the touch plate.

However, I think I’ve figured out the problem, which leads to more questions…

My z axis is only moving ~2.5mm for every 10mm commanded.

This is the lead screw I used, diameter and pitch as the links recommended

Capture
Capture1170×676 85.4 KB

4

Ok, I figured it out… I had a 2mm/revolution lead screw installed, where I should have had an 8mm/revolution. I swapped out the screw and nut and it works great.

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