Z-Probing Instructions?
I am trying to set up my z-probe in accordance with this:
What is the Znew and Zold in this equation represent they are not mentioned int he instructions:
ZHnew = ZHold + Z0 + Znew - Zold - ref_height
Comments
And note the z height as Zold. Next we adjust z until the metal block fits exactly below the nozzle. You will see that when you have a gap you can easily rotate the block. If you are too low, it will give a “clong” sound when you press bed down. This makes it much more exact then the typically used sheet of paper. Once you think you found exact level, send M114 again and note it a Znew.
So what we now have is starting height as firmware would assume it from first probe Z0 using our initial Z_PROBE_HEIGHT (ZHold). We also know that we needed to go up Znew-Zold to reach ref_height. From this we can compute the exact real value required from Z_PROBE_HEIGHT (ZHnew):
See how I do it and show me, please, where I understood your instructions wrong way.
Prusa acrylic. No hardware Z-stops, neither min, nor max. Capacitive sensor is connected to Z-min pin with resistor, correctly reports L to M119 when not triggered and H when triggered.
1/ Z-probe height in EEPROM is 0.6
ZHold=0.6
2/ QUOTE: “First we go close to the bed at a distance that the z-probe does not trigger and send a G30 P0”
We start 10 mm above the bed and send G30 P0 and get
< 23:37:19: Z-probe:9.67 X:100.82 Y:99.80
We memorize z0=9.67
3/ Now we heat up the nozzle, clean it and send M114:
< 23:41:07: X:100.00 Y:100.01 Z:10.000 E:0.0000
Zold=10
4/ The metal block we have has height of 21.9 mm
ref_height = 21.9
QUOTE: “Next we adjust z until the metal block fits exactly below the nozzle.. send M114 again and note it a Znew.”.
So, we lift the nozzle up until it touches the block. M114
< 23:47:08: X:100.00 Y:100.01 Z:21.900 E:0.0000
Znew=21.9
5/ ZHnew = ZHold + Z0 + Znew - Zold - ref_height
ZHnew = 0.6 + 9.67 + 21.9 -10 -21.9 = 0.27
6/ We change in EEPROM Z-probe height from 0.6 to 0.27
Here, just to know, we move the carriage down until sensor gets triggered. Then we move it lower with 0.1 mm steps. After 7 steps = 0.7 mm we feel the friction of paper sheet between bed and nozzle. This simple paper sheet test tells us that Z-probe height is 0.7 mm. We just note it for later.
7/ sending G32
Trying to print: filament is not smeared on the bed but lies on it without adhesion. The nozzle is definitely too high above the bed.
8/ Changing the Z-probe height in EEPROM back to 0.6 and sending G32 and then printing: nice smear, adhesion and good print.
I could live with calibration with paper sheet. But I like the Repetier Host and Firmware. And I like to understand it. And I like other people to understand it and work with it. Thank you for explanations on this and other questions as well.