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[Closed] Selftest - X Axis Length  

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Laen
 Laen
(@laen)
Active Member
Selftest - X Axis Length

Hi! I just finished assembling my new MK3, and during self-test, I'm getting:

Selftest error! Please check:
Axis Length
Axis X

Beforehand, the X axis goes back and forth between the end-stops.

What could be causing this?

(Firmware 3.1.1-RC1 b121)

Posted : 06/12/2017 9:48 pm
Josef Průša
(@josef-prusa)
Member Admin
Re: Selftest - X Axis Length

Check if the x carriage touch the xends on both sides. Sometimes nozzle cooling fan wires or something else prevent it ...

Founder and owner / Majitel a zakladatel
Posted : 06/12/2017 10:06 pm
Lukas liked
Laen
 Laen
(@laen)
Active Member
Topic starter answered:
Re: Selftest - X Axis Length

Ah ha! The zip-tie stub from the hotend wires was bumping against the frame. Moved them a millimeter and it's calibrating just fine now.

Thanks!
-Laen

Posted : 06/12/2017 10:21 pm
Josef Průša
(@josef-prusa)
Member Admin
Re: Selftest - X Axis Length

Yeah, it is pretty clever little machine. We can measure the axis length and compare it to what it should be 🙂

Happy printing!

Founder and owner / Majitel a zakladatel
Posted : 06/12/2017 10:24 pm
Macca
(@macca)
Eminent Member
Re: Selftest - X Axis Length

😮

Thats some pretty smart self diagnostics !

Posted : 07/12/2017 10:35 am
JMcK
 JMcK
(@jmck)
Reputable Member
Re: Selftest - X Axis Length

One might even say the printer is “bloody smart”

When someone asks you if you're a god, you say, "YES!"

Posted : 07/12/2017 12:11 pm
Josef Průša
(@josef-prusa)
Member Admin
Re: Selftest - X Axis Length

We can also measure the belt tension 🙂

Founder and owner / Majitel a zakladatel
Posted : 07/12/2017 12:14 pm
maxx78
(@maxx78)
Estimable Member
Re: Selftest - X Axis Length


We can also measure the belt tension 🙂

couldn't you use the same method for the Z-axis and get rid of the Pinda ?

Posted : 07/12/2017 1:01 pm
Sulya
(@sulya)
Trusted Member
Re: Selftest - X Axis Length


couldn't you use the same method for the Z-axis and get rid of the Pinda ?

According to me that would mean crashing the nozzle onto the print surface. And since the distance calibration has to be done with preheated bed that could result in holes overtime.

Posted : 07/12/2017 4:05 pm
maxx78
(@maxx78)
Estimable Member
Re: Selftest - X Axis Length

"Crashing" sound a bit harsh, from what i have seen on my printer i think it might be possible. But they probably thought about it & made some tests

Posted : 07/12/2017 4:19 pm
Josef Průša
(@josef-prusa)
Member Admin
Re: Selftest - X Axis Length

We theoretically can preset the Live adjust Z distance. Wait for the probe to register the bed, and go down until the nozzle hits the sheet.

Founder and owner / Majitel a zakladatel
Posted : 07/12/2017 4:30 pm
Sulya
(@sulya)
Trusted Member
Re: Selftest - X Axis Length

Hmm, maybe its not possible because of the threaded rod- while x and y axes are direct belt-driven, z axis has threaded rods that also act like reduction gearbox, decreasing the travel distance while increasing the torque. So the nozzle will be pushing really hard into the print surface before the motor would skip the step that can be detected by the trinamic drivers.

[EDIT] Oops, looks like Josef replied before me. Leaving this comment here anyway because of the concerns mentioned

Posted : 07/12/2017 4:31 pm
maxx78
(@maxx78)
Estimable Member
Re: Selftest - X Axis Length


We theoretically can preset the Live adjust Z distance. Wait for the probe to register the bed, and go down until the nozzle hits the sheet.

Ok, nice but not a way to get rid of the PINDA.
But you need it any to detected a skewed platform.

BTW.: You made the MK3 so silent i can hear the bearings rolling 😯 I love it so far.

Posted : 07/12/2017 4:36 pm
rotarypower101
(@rotarypower101)
Estimable Member
Re: Selftest - X Axis Length



We theoretically can preset the Live adjust Z distance. Wait for the probe to register the bed, and go down until the nozzle hits the sheet.

Ok, nice but not a way to get rid of the PINDA.
But you need it any to detected a skewed platform.

BTW.: You made the MK3 so silent i can hear the bearings rolling 😯 I love it so far.

...maybe they do need the igus bearings as replacements for those ear piercing linear bearings 😁

Posted : 07/12/2017 7:07 pm
Nullzero
(@nullzero)
Trusted Member
Re: Selftest - X Axis Length

There was another thread about the self-test x-axis length failing with an error. But there was a chinese hack on the boards, and I think that thread got deleted.

Just for future note, I had the same problem at first, then rotated my zip-ties so they don't hit the sides of the frame.

Then later, I tweaked my x-axis belts to make them tighter. Only when I tried to re-calibrate, I could not get my x-axis to calibrate without failing. And it was flush to the left side of the frame, with no gap. Maximilion pointed out that the calibration and self-test will FAIL if you have Stealth Mode engaged in the settings! This fixed my problem immediately! For future reference!

Posted : 12/12/2017 4:44 pm
Peter
(@peter-12)
Estimable Member
Re: Selftest - X Axis Length

I would have thought that selecting calibration and self test automatically disabled stealth mode. o_O

Posted : 12/12/2017 5:28 pm
maxx78
(@maxx78)
Estimable Member
Re: Selftest - X Axis Length

it stays in stealth mode and the result looks like this:

Posted : 12/12/2017 9:05 pm
NSFWAA
(@nsfwaa)
New Member
Re: Selftest - X Axis Length

In Step 35 "Mounting the X-carriage-back"(5. E-axis assembly) I apparently tightend the 2 screw on the top to much, as soon as I losend them the Selftest - X Axis Length worked.

Posted : 12/12/2017 10:56 pm
Josef Průša
(@josef-prusa)
Member Admin
Re: Selftest - X Axis Length


I would have thought that selecting calibration and self test automatically disabled stealth mode. o_O

Yes, sometimes things like this slip thru. Next FW this week accounts for that 🙂

Founder and owner / Majitel a zakladatel
Posted : 13/12/2017 12:51 am
kelchm
(@kelchm)
Eminent Member
Re: Selftest - X Axis Length

Then later, I tweaked my x-axis belts to make them tighter. Only when I tried to re-calibrate, I could not get my x-axis to calibrate without failing. And it was flush to the left side of the frame, with no gap. Maximilion pointed out that the calibration and self-test will FAIL if you have Stealth Mode engaged in the settings! This fixed my problem immediately! For future reference!

I ran into the same exact issue. Thanks for pointing this out!

Posted : 16/12/2017 2:18 am
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