Trouble getting Z-probe auto-calibration to work on Kossel/Duet

Hello,
This question is regarding a Mini Kossel with Duet electronics running dc42's firmware version 1.04e (I know there's version 1.04f out there but bear with me) and controlling via the version 1.06 web interface. When I run bed.g the head homes properly but then drives itself into the bed causing general mayhem. I was expecting the machine to probe the bed carefully at 10 locations. I'm using the microswitch-type probe. I believe the machine is working properly otherwise, running the octagon-test-delta file drives the head to Z=100mm above the bed and runs the head around in X-Y in the expected shape. I felt I was ready to move to auto-calibration at that point. I've performed the following steps prior to executing bed.g file:

Adjusted M92 for my machine's steps/mm (100), Z axis reports distance traveled = distance the carriage physically moved, measured along the rails
Adjusted M665 H parameter to reflect height above bed when homed (H=230)
Set M558 P parameter to "4" indicating switch for the Z probe; web interface responds to switch, 0=deployed (microswitch active), 1000=stowed
Moved head to just touching bed (grabs a piece of paper), sent G92 Z0, web interface reports that head is at Z=0
Raised head, deployed Z-probe, determined Z-probe activates microswitch at Z=8mm, set G31 Z and P parameters (Z=8.0, P=500)
One thing I did was to comment out deploying and retracting the Z-probe in bed.g as I am doing it manually; I note those macros contain the "M564 S1" command to set limits...is this a problem that I'm not executing that command before continuing within the bed.g instructions?
Uploaded the final config and bed files to the appropriate locations on the SD card
"Printing" bed.g results in the head homing properly, then driving down through the bed and running around, have to kill power to stop the craziness.

Any help would be greatly appreciated!!!

Blake

Edited 1 time(s). Last edit at 05/16/2015 07:37PM by blakebart.

Hi Blake, I think the problem may be that my Z probe triggers at about 4mm so I set the Z dive height in the sample config.g file for the Mini Kossel to 8mm. If your probe triggers at 8mm, you need to set a higher Z dive height, e.g. 12mm. The Z dive height is set by the H parameter in the M558 command in config.g.

The reason for the M564 S1 commands is that the deploy and retract sequences move the head outside the normal print radius. You do not need this command if you are deploying and retracting the probe manually and your bed probe points are all within the normal print radius, as set by the B parameter in the M665 command.

Edited 2 time(s). Last edit at 05/17/2015 03:46AM by dc42.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi David,

Thanks as always for the quick reply. It's working now. In the config.g file I was using, the H parameter of the M558 command was not there, so I fixed that. I just checked the config.g file in your RepRapFirmware-dev fork and the H parameter is there, so I was using an older release. Still it was good to go through this exercise and learn about some subtleties.

Cheers, David!

Blake

Quote
blakebart
Thanks as always for the quick reply. It's working now. In the config.g file I was using, the H parameter of the M558 command was not there, so I fixed that. I just checked the config.g file in your RepRapFirmware-dev fork and the H parameter is there, so I was using an older release. Still it was good to go through this exercise and learn about some subtleties.

I'm glad you got it working. Is the automatic delta calibration working well for you?

I will shortly be releasing firmware version 1.09. In this release, I have made the Z dive height relative to the Z trigger height, and reduced the default from 5mm to 3mm. So you should be able to remove the H parameter from M558 when you upgrade to the new firmware.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hi David,

I'm about to make my first print and will let you know, but it does modify my x and y positions a couple mm after completion which is in the ballpark of error of where I set my endstops if I understand this correctly. Yes I just saw 1.09 in your fork, I'll get some prints under my belt then upload the new firmware and associated files.

The next area I'd like to understand is axis compensation. I've seen that people print cubes and verify dimensions but I think the point of axis compensation is to make sure surfaces that are supposed to be orthogonal to each other are. Do you have a recommended object for making the measurements to put into the 556 parameters?

Thanks again for all your help and work with this community.

Blake

Quote
blakebart
The next area I'd like to understand is axis compensation. I've seen that people print cubes and verify dimensions but I think the point of axis compensation is to make sure surfaces that are supposed to be orthogonal to each other are. Do you have a recommended object for making the measurements to put into the 556 parameters?

In [github.com] you will find .scad and .stl files for a part called OrthogonalCalibrationPiece. You may wish to scale it to suit the size of your printer. The part that RepRapPro suggests for the Ormerod printer has a second piece with a screw to measure the angles - see [reprappro.com] for the instructions. You can find the STL files for it at [github.com].

Edited 1 time(s). Last edit at 05/17/2015 05:33PM by dc42.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Got it, David, thanks. I now see that is the object that is being measured in the picture associated with the RepRap wiki on g-code 556, and thanks for the link to the RepRap page about this. I get it now.

Blake