Print bed homes properly, but drops to begin printing

[Jules]

Wouldn't the Z endstop bolt be compensating for the height difference of the V3b vs V4 already? It just sits the 5-6mm higher.

Sorry....that's the way my brain just pictures it, and it might not be what actually causes it.

I remember several people had the problem when we switched to the V4s, and it was limited to just those sample files on some of the SD cards, and I knew the V3B sat about that much lower. So i thought maybe the hard code on some the cards might have been pre-loaded and thought it was dealing with a V3B and not V4. There's no way for us to look at the file on his SD card.

I'm not sure that is what causes it at all....so that's why the test over USB connection with a non-sample file. If that works out okay, then it is a bad sample file for whatever machine setup he currently has. (It's basically just a test.)

I don't begin to understand how the coding works in the firmware, and i caused a lot of heartburn over it when i tried to apply the old way of thinking to the Rev E style machines.
(Just ask Josh.......chuckle. I wasted an entire weekend fretting over nothing.)

[Jules]

You grossly overestimate how much of a personal life I have

Ditto that!
(We're usually around.)

[Raddiver]

Ok folks.
Downloaded and printed the calibration stl via usb.
Same deal. bed still drops about 5-6mm
I also ran through the getting started guide:
Reset home to .21mm (cold endstop)
Then i made it to the print for calculating the z-offset. . . . .

[Raddiver]

maybe M2Marlin-11-30-2015 firmware? Global reset?
If im reading configuration.h correctly...
m502 should overwrite current settings to factory defaults, and then m500 should re-write the factory defaults back to EEprom... Yes?

[Raddiver]

Eureka, I think i found it!
M206 returned as X0.0 Y0.0 Z-6.0

[Jules]

If it's not just those two sample files - it must be something in either the firmware or the software (like a huge Z-Offset value) but i can't imagine why you would inherit a printer that had incorrect firmware loaded into it. 5-6 mm is an awful lot for the bed to drop.

(When you loaded S3D, did you choose the correct configuration for the MakerGear M2?)

You might need to try a different firmware - the link to the correct versions for the various machines is below:

http://makergear.wikidot.com/m2-firmware

(Pay attention to the color of the Z-axis motor when choosing the correct version. Either a silver motor with black band, or all black motor.) And in order to load it, you need to use Arduino 1.5.5 - some of the more recent versions have had issues with loading correctly.

[Jules]

Eureka, I think i found it!
M206 returned as X0.0 Y0.0 Z-6.0

(I've got to learn to type quicker!) Chuckle!

[Raddiver]

Thanks for the help Jules and Insta.
First successful print just completed. Just waiting for it to cool down before i pop it off the bed. It isn't pretty but it printed.
Man that was um.... Fun [/sarcasm]. My arduino-fu kicked in there for a sec.
I appreciate the help you guys gave pointing me in the right direction.
At least i have a starting point now, so I can tweak from here.

[Whitey]

I read this note and am having a similar problem with a Rev E brand new device.

I have printed for 80 hours and then suddenly the Z home changed and now the home position will not go to the set level that I put the bed for a .1 print.

I have gone through multiple bed leveling steps with M2 quickstart, Printrun, and Simlify 3D. Each time, the bed is level to the blue spacer paper and when I go to print, the nozzle is 20 mm away from the glass bed. It is very frustrating and appreciate anyone's help.

Whitey