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random X offset

Posted by Gnarrr 
random X offset
February 28, 2015 02:34PM
Hi, I asked before a similar question see: printing shifts on X-Axis [forums.reprap.org].
I use:
- Prusa mendel
- Power: ATX 250W
- 1.4 Ramps
- Marlin Firmware

but the problem seems to have changed.
while printing some parts are shifted to the right +X, for example only the infill or only the rim or one whole part. Then the next layer may print normally, but the error is repeating. I think the errors occure always on the same points in the printing process of one G-code but it is different for every G-code.
So it is no constant offset. the G-code looks fine and i checked every hardware part: changing the motordrivers does nothing, i already increased the voltage on the drivers a little.

Now I'm clueless and not even sure if it is a hardware or software problem.

please help.

PS:is there something better than painters tape for pla printing? it wont stick.
Re: random X offset
March 02, 2015 05:17PM
I have a similar problem with an replikeo Prusa i3 (Ramps1.4, marlin)
Left of the center point on the x axis (edit: seems to be left of the center of the model or at least more likely there) infill and lines sometimes seem to get offset in X+ direction. (Have not testet printing a part only on the side where it seems to work good yet)
I have reinstalled every Software component I use, switched from Cura to Slizer, Used an SD card instead of Pronterface... Also looking at the paths in Pronterface the gcode seems to be fine.
I even watched the Printer to make shure it doesnt skip steps.
The Strange thing is on my main testing print for this it seems to consistently keep one infill edges about 2mm away from the perimeter while printing the rest of the infill not even offset, but strechtched. AND in the same layer, there are parts printed just fine aligning perfectly each layer.

Sampel Pic [www.dropbox.com]

From a logical standpoint I would suggest it is an Problem in Marlin since Pronterface shows the correct paths, but Changing that to a completely new version didn't help either.

Will make sure to inform you if i can find a fix.

And for the bed adhesion. I use gluesticks on simple 3mm pictureframe glass. Works like a charm - almost not able to remove the print hot! But it's even popping the print off as it cools down. But since PLA uses lower Temp. it might be to low for that.

Edited 2 time(s). Last edit at 03/03/2015 11:53AM by Whatnever.
Re: random X offset
March 02, 2015 06:18PM
It sounds to me that the printer is missing steps for some particular type of X move. Try decreasing the maximum X acceleration, or the maximum X jerk, or increasing the X stepper motor current a little if the X stepper motor is running cool.

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].
Re: random X offset
March 03, 2015 06:26PM
Nevermind the setscrew on the beltgear was a little lose. This caused some backlash, because it was only holding it on the very edge of the flat side of the rod. ;D
Picture to the problem
March 07, 2015 05:05PM
Ok, i tried to lower the X-acceleration/-jerk and nothing changed.

But now i have a picture of the problem, the arrow is pointing to the point were the printer suddenly decided to correct the mistake. How is this possible?

does anyone know what is going on here?

Re: random X offset
March 12, 2015 02:02PM
you are a genious.

that was it. i first didn't belived it.
now it's printing perfect

it's always the small things
Re: random X offset
June 16, 2017 10:58AM
Thank you so much Whatnever! 3 years later and your post is still helping others grinning smiley
open | download - 2017-06-17 00.57.33.jpg (194.8 KB)
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