SOLVED: X Axis doubles near the end of the print

This is happening almost every print. Everything starts out fine then about 3/4 the way through, the Y (EDIT its the X axis not the Y) Axis elongates. I measured it and it is about double, then I restart and it's normal again.I am using latest sprinter version with least pronterfacae/slic3r. I am printing on an ORD Bot with RAMPS 1.4 on a Mac Mini running 10.7.4

Edited 3 time(s). Last edit at 09/10/2012 02:23AM by PrepackedScreens.

are you using aluminium ,pla or abs timing pulleys

I believe they are made out of Delrin brought from here

hmm i'd double check the set screw (which you've probably done a dozen times)

assuming it's not that i would pull the pololu out of the x and y axis spots and swap them and see if them problem switches to the other axis,

if it does then i'd say it's the pololu doing somthing funny as it gets nice and warm and may need to be adjusted

if it stays on that axis then there is some kind of hardware problem,

if it tuns out to be the pololu i would turn the feedrate down a bit

Well played sir, thanks for your advice. I will post my fix.

Looks like there is a bad connection on the pins / jumpers that set the microstepping mode. I.e. it switches from x16 to x8.

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Do the position values in your G-Code double?

The program repetier lets you visualizes the G-code in 3D.

If your G-code is fine, then I bet Nophead is right, it changes micro stepping values for some reason.

"Looks like there is a bad connection on the pins / jumpers that set the microstepping mode."

That sounds logical. A cold junction on the ramps (poor soldering) could cause that situation very easily, especially if the board is mounted to the printer like so many people seem to do. (ime, high vibration environments are a torture test for electronics assemblies and generally reveal any and all problems in the soldering or other mounting characteristics)

Thanks everyone for helping me out. Nophead, you nailed it, sort of. It wasn't so much a bad connection in the jumpers that caused the problem...more like NO CONNECTION! While I was swapping X and Y drivers, there it was, On my Ultimachine diagram it says "MS3" but lets just call it the last Y-Guy on the right who, when absent changes the config to 1/8th just as you predicted.

So now, even though I'm happy I got that straightened out, it leaves me wondering how did I ever got ANY decent prints. Any thoughts?

Ryan