Selftest Error: X Axis length  

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carsoncrull
(@carsoncrull)
New Member

Hello! Last week I received and built my MK3S kit, and was immediately able to begin printing without any problems.

However, a few days ago I noticed that my prints were showing signs of a staircase effect in the X Axis direction. I re-ran the selftest, and was unable to get past the X Axis check, always receiving the "X Axis length" error. I noticed that the zipties on the wires leading out of the extruder were hitting the right side of the printer frame, but after making sure there was no contact I was still unable to pass the selftest. I tried tightening the belt, and after tightening, noticed that the wires from the hotend were making contact on the left side of the frame, and the nylon sheath was again touching the right side. I am now unable to position the wires in any way that avoids contact with the sides of the frame, and am unable to pass selftest.

Posted : 18/07/2019 9:57 pm
holmes4
(@holmes4)
Estimable Member

This probably doesn't help you, but when I recently had this error I had made a mistake in the firmware I uploaded so that the printer thought the steppers needed twice as many steps for the same distance.  Given your comment about "staircase effect" I wonder if the X-axis gear is not properly attached to the stepper shaft and is slipping.

Posted : 18/07/2019 10:57 pm
carsoncrull
(@carsoncrull)
New Member

How would I tell if the X-axis gear wasn't attached properly?

Posted : 20/07/2019 5:21 am
Tim
(@tim-m30)
Illustrious Member

I think you've identified at least part of the problem.  All wires MUST be free and clear of the frame and EINSY case.  It is possible to do.  Even the extruder cooling fan wires are often misplaced and keep the extruder from homing properly. Or the fan screws are not fully seated or the wrong screws were used and the heads hit the lead screw ...  millimeters count.

This post was modified 1 year ago by Tim
It is always wise to get more than one opinion......
Posted : 20/07/2019 8:39 am
tim-8 liked
holmes4
(@holmes4)
Estimable Member
Posted by: carsoncrull

How would I tell if the X-axis gear wasn't attached properly?

You'd want to make sure that one of the setscrews was tight against the flat of the motor shaft. If both setscrews are against the rounded part, that could cause slippage.

Posted : 21/07/2019 8:43 pm
Tim
(@tim-m30)
Illustrious Member

Flat First: Drive gears must be tightened flat-first.

1)   Start with both set screws fully loosened so the pulley is free to spin on the motor shaft.

2)   Align one set screw dead center with the flat on the motor shaft, slowly tighten the screw until it fully contacts the flat surface.

3)   Torque the flat set screw to spec.

4)   Now tighten the jam set screw, and torque it to spec.

Once tightened, never touch the flat set screw unless the jam screw is first fully loosened.

Why Flat First? Set screws have flat ends. If you tighten the jam screw first the set screw on the shaft flat doesn't fully contact the shaft, only one small edge of the screw surface is biting. Reversing torques can easily shift the shaft to a position the flat screw no longer contacts the shaft. This lets the jam screw wriggle loose. And after a while, vibration loosens the screws until the gear is free to rotate.

 

It is always wise to get more than one opinion......
Posted : 21/07/2019 10:26 pm
spencer.k3
(@spencer-k3)
New Member
Posted by: @carsoncrull

Hello! Last week I received and built my MK3S kit, and was immediately able to begin printing without any problems.

However, a few days ago I noticed that my prints were showing signs of a staircase effect in the X Axis direction. I re-ran the selftest, and was unable to get past the X Axis check, always receiving the "X Axis length" error. I noticed that the zipties on the wires leading out of the extruder were hitting the right side of the printer frame, but after making sure there was no contact I was still unable to pass the selftest. I tried tightening the belt, and after tightening, noticed that the wires from the hotend were making contact on the left side of the frame, and the nylon sheath was again touching the right side. I am now unable to position the wires in any way that avoids contact with the sides of the frame, and am unable to pass selftest.

Can't comment on an issue developing over  time, but one tip- if, after modification or upgrades (like going from MK3 to MK3S / MMU2S like I just did) , and the x issue comes up, you probably have a zip tie upside down. the head of one of mine was pointed to the edge and was limiting the x travel by a mm or two. cut it off, and we're golden.

Posted : 31/05/2020 8:23 pm
jppalkovits
(@jppalkovits)
New Member

I completed my build last night and ran the self test this morning.

My error was caused by installing the x-gear backwards causing the belt tp rub on the 3D printed part.  

Comment may be useful for new people troubleshooting.

Posted : 09/07/2020 4:43 pm
tim-8
(@tim-8)
Active Member

We had that issue as well.. it was the fan wires that weren't tucked back far enough which didn't allow the print head to fully move to the far left of the x-axis

Posted : 09/07/2020 6:32 pm
pmplhokxfjpcsybkad
(@pmplhokxfjpcsybkad)
New Member

Hello, I have the same issues with the X axis length and it does not move at all. I tied lubricating the rods, flashes the firmware and checked the cables and zip ties. I just can't find what is wrong with it. Any ideas?

Posted : 08/08/2020 3:45 pm
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