X axis randomly changing position.

OK, it has been a while since I have had a problem with my prusa that I havn't been able to fix, but right now, im completely stuck.

The printer has been working fine for a month or two with no major problems, but all of a sudden, in the middle of my prints, the X axis is deciding to jump to the right.
i've attached an artists rendition below as I have no pictures at the moment.


The above artist rendition is an example of what is happening.
The X axis is starting the print in a different position. The Y and Z axis' are fine, and it isnt the motor skipping steps. It does it silently with no clicks or bangs.

I believe it is something to do with the software (nothing has changed with the software on the printer or computer since I started) and each model I have this is happening.

Anyone have any experience with this problem?

Do you have a fan on the drivers?

I do.

Here is an actual picture of it messing up multiple times in the first few layers of the print.

i've tried taking the entire x carriage apart and putting it back together with no luck.
Anyone have any ideas?

First thing to find out is if it happens at the same height or place in the print.

different every time. sometimes its once through the whole print. sometimes its many.
sometimes 3 layersin, sometimes 10, etc

Next thing is to cut the speed in half, and see if it helps.

i broke it down again (basically rebuild the entire carriage and extruder and it seems to have fixed. I think it was an excess of oil building up in the bearings. If not i'll update this when it does it again.

It's back.
i'm almost about to get a hammer.

OK, i have now took the entire x carriage apart and back together... it still jumps. here are my prints for a 2 hour print last night.


The jump is ALWAYS to the right.

the belt is tight, the motor is running fine. I'm baffled.

Put a cooling fan on the driver board and see if that helps. Looks like a driver is getting hot and as a result screwing things up.

The driver has two fans on. one intake and one out take into the box i printed. the intake is directly over the drivers.
im currently running at 70% speed and its still skipping. not on the same layer either.

Currently printing each letter seperatly now to minimize losing prints as i have orders to fill.

it fails around one in every 3 prints (40 mins print time at 70 percent speed)

the printer has been running for around 6 months and i've not seen this problem before.

Are you printing from an SD card or via a PC?

Via PC, using Repetier host.

4.5Ghz AMD 6300 Six Core
8GB DDR3 RAM
AMD HD7700 series graphics card.

nothing else running other than maybe watching a video every now and again. and its skipping when nothing else is running too.

It may be noise on the USB?
Maybe try change the USB cable or print from SD

i'll give it a go

I've not got an SD chip on my RAMPS, but i tried a different USB lead and it made no difference.

Recheck your stepper voltages. Bet the X-axis stepper motor is getting to hot and thermal protecting for a second. Can you touch the motor after it has been printing a while?

I could lick the motor if I wanted to haha.
The heat is fine.

I "Think" i've found the problem... but this is just a guess at the moment, it has worked for one 2 and a half hour print.
Basically the X endstop may be malfunctioning (maybe the wire has come loose or a connection somewhere just isnt quite right. Maybe I just need a new one.
The signal from the malfunctioning endstop is trigerring the carriage to go right every now and again.

Atleast this is my theory. I rewired the endstop and repositioned it somewhat, it has worked for one long print. i've set another away now, fingers crossed.

Hey I had that problem with my kit, one of the wires on the x axis was not crimped good. I replaced the wiring and haven't had a problem since.