Understanding Probing and Trigger Z Height

waruta
Posts: 33
Joined: Tue Apr 25, 2017 1:23 am

Re: Understanding Probing and Trigger Z Height

Post by waruta » Mon Sep 25, 2017 4:15 am

snafu wrote:
Fri May 05, 2017 3:34 pm
I figured it out. You use G92 to adjust Z0 and then proceed to use extremely small movements to get the rolling paper pinned comfortably. Set that point as Z0 with G92 Z0, raise the head slightly, and finally run G30 S-1 to get the Z trigger height offset. Which in my case is -0.10 as opposed to -.15. I tested it at several points and they were all within .01 mm of -.10, which I'm sure is fine.
How did you use G92 to adjust? I'm getting excellent G32 auto calibrate results (0.012 and lower ) but when I try and lower the head using the machine control panel (z-100,z-10 etc...) the head just won't pin the rolling paper. In my config.g file, the G31 is Z -0.138 . in Config.g (this is after running a full autocalibrate, then G30 S-1, the getting Z height using M114 and changing G31 Z parameter as mentioned in the blog post)

Then 5x autocalibrates, then issue M500 command to ConfigOverride.


Some prints have come out great, others will not even adhere to the surface while all parameters (temp, bed temp etc...) are the same.

Before I reinstall PEI, I wanted to make sure that all my z calibrations are correct and reprint the 0.2 mm single layer test. Thanks!

waruta
Posts: 33
Joined: Tue Apr 25, 2017 1:23 am

Re: Understanding Probing and Trigger Z Height

Post by waruta » Mon Sep 25, 2017 5:20 am

Printed a single layer test, average measurement was 0.227, so I subtracted that (0.027)from the original Z-0.138 to get a final height of Z-0.111.

Ran autocalibrate macro x5, got numbers in the range of 0.012-0.015 (see pic)

So the question is - all good? I'm not doing anything wrong?
Attachments
Capture.PNG

Steve

Re: Understanding Probing and Trigger Z Height

Post by Steve » Sat Mar 24, 2018 2:34 pm

Michael

I followed your instructions on setting Z Height using Baby Stepping.
I printed the 75mm Disc and found that I needed -.2 adjustment.
I edited the config.g file and added that amount to the G31 Z= command.
I rebooted the Controller and checked the config.g file to be sure the edit took effect.
I reprinted the 75mm disc and there was no change.
I did notice that there is a M501 command at the end of the file.
is that affecting the change?

Steve

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UltiBots
Posts: 602
Joined: Fri Apr 21, 2017 10:18 am

Re: Understanding Probing and Trigger Z Height

Post by UltiBots » Mon Mar 26, 2018 9:42 am

Steve - Nice talking with you. Thanks for the call. You helped me discover a glaring omission to our guide; that is... it was written prior to the inclusion of the config-override feature in RepRapFirmware.

Our kits currently ship with RRF version 1.19.2. This version allows you to save auto-calibration settings with M500. As discussed I recommend issuing G32 3 to 5 times sequentially and then issue M500 to save the calibration settings. The result will be a new file is generated called, config-override.g. This file stores the auto-calibration settings for future prints.

The current config.g file shipping with our kits defaults to a Z-0.25 offset for first layer smush. You may need to adjusts your first layer smush with baby steps. Test print and use baby steps to adjust the first layer. Repeat the print using the baby steps from the first test to confirm is is OK.

Post back your results. I will detail how to save the baby step offset for future prints.
Brad - UltiBots LLC

piglet74
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Joined: Sun Mar 18, 2018 9:37 am

Re: Understanding Probing and Trigger Z Height

Post by piglet74 » Tue May 08, 2018 3:44 am

Hi I was wondering if you have those commands to save the offset. I commissioned mine recently and have noticed that my first layer is inconsistent. I use a .203mm feeler gauge to check the height to the bed and then changed the G31 line in the config.g to adjust for the difference. For example, if the .2 gauge is starting to drag at .35 then I have to add .15 of negative z. Calibrations usually run at about .011 dev. I stopped doing one before each print though because oozing caused a pretty bad calibration run before a print and I had to cancel it.

If after setting the offset, I run a calibration and the machine thinks the height is different than what is in the config, should I ignore the new height or should I enter it into the config and reboot. I just want to avoid chasing my tail.

Thanks, Rob.

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UltiBots
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Re: Understanding Probing and Trigger Z Height

Post by UltiBots » Wed May 09, 2018 11:33 am

@Rob - I don't know the command to save the offset. We set the "typical" offset in the config file and run auto-cal each print. We monitor the first layer and use micro stepping to tweak the first layer. I recommend posting on the Duet forum and/or join Michael Hackney's Slack channel. More info at www.sublimelayers.com. Please post back your findings!
Brad - UltiBots LLC

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