Prusa i3 x-axis drift

Hi all,

First post on here - I've been soldiering on by myself till now, but this one has got me stumped.

I have made a Prusa i3 single plate (aluminium) and have been getting ok results until the last week or so.

I keep getting this random drifting of the print on the X-axis (the one attached to the z-axis in case I have got it wrong). A print can be going fine for and hour and then just start to drift off by 2-3 mm, then it tends to hold for a few layers before starting to drift further.
My belt is tight and I'm positive that it's not jumping a tooth. The motor is hot, but I can still hold my fingers on it, so it's not burning up.

The electronics are pololu from Tony Lock and have been spot on so far.

I have tried 2 computers, a windows 7 laptop and a macbook - both running repetier and using slicer.

Both slicer graphics look perfect on screen - the numbers look good in the code - the drift has got to be somewhere else... It's driving me bonkers!

I have mainly been trying to print the parts for richraps 3dr, but other files have failed too - it's not the STL files I'm pretty sure.

If anyone has any ideas, I'd love to try them - I think I'm running out of steam :-)

Cheers,

Ian

If the drift occurs along +ve direction of X It might be because of Limit Switches,
if your x axis limit switch wiring is cut off, the drift may occur because the printer assumes the zero is reached when going to negative direction so it won't go beyond -ve direction during printing

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Also take a look at your motor pulley. Maybe it's slipping from time to time. You could mark your motor axis and your pulley so it's easier to identify a slipping pulley.
Loosing steps could also be a reason.

Thanks for the replies guys, Sorry I have been a while geting back to this - time has not been on my side these last few days...

I think both points are valid, but, I'm looking for another reason.
My limits are wires normally closed. They break when the hotend is home, therefore if the wires had broken, it would see home position from anywhere along the x-axis. If my print starts 50mm over (for example), would the shift be relative to the start position?
I have checked the wiring with a DVM and it seems to be good.

The second point about the pulley moving is also something I have checked (although leaving a permanent marker on the home position is something I hadn't done and I think is a great idea).

Your comments about losing steps led me to look at overheating of the drivers (Ramps 1.3). I'm considering swapping over the x-axis and extruder drivers to see if that makes a difference. I thought it may be overheating as the fault is really obvious on long prints over about 1 1/2 hours.

Just to scupper the above idea, I have just started a print which failed on the second layer!

Using repetier on the MAC, I have just restarted the print with NO changes - same slicer g-code - it has gone past the second layer without event! MAN this thing is really annoying!

I think I will try exporting the g-code to the memory card and printing from there, but as of now, I have still got the same issues.

Thanks in advance for any help anyone can offer :-)

I'm just looking for that one thing....

Cheers!

Ian

Ian Post some photos of your print

It will help to understand the issues in your printer

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Hi again, Thanks for the reply.

I have no excuse, it was just laziness on my part - Photos! genius.

I have attached 2 - they are supposed to be the centre lower base of Rich Hornes 3DR delta printer.

The drift just seems to happen at random stages. Sometimes with 2 layers, other times right at the end of the print. Other than this, the quality has been quite good - it's my first build.

The home position switch is on the left (looking from the front) and the drift is always towards the home switch. You can see in the picture drift1, that it has drifted, started to print some more layers, then drifted again and once more after that. It's a mystery for me.

Thanks for taking the time to help - I really do appreciate it

Ian

Edited 1 time(s). Last edit at 12/09/2013 12:48PM by BAD455.

I suspect Limit Sensor wiring (including connectors) also check the Stepper Driver is overheating ! Over heating of stepper driver causes you missing steps. Have you provided heat sink for stepper drivers ? also try PC cooling fan to blow away the heat from the stepper Driver

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I had similar problems with my Z axis and it turned out the trim wasn't set right and the built in overstress limiters of the (Allegro) Pololu drivers were kicking in.

Sorry to jump in but dshay.
What “trim” are you talking about?
I have a MendelMax 1.5.

I have the same issue with my Z on and off.
I don’t think it is the same issue as below for the X but it may be.

BAD455
And now I just started having the same issue with the X axis also.
But I think I have figured it out!
I have not had time to check it out yet but here is the theory.
My filament sits on top of my printer on bearing and a full roll is about 2Lbs.
I have seen the filament get tight and then I roll it some.
So if it gets to tight then the X axis is going to miss step because of the drag on it form the filament.
So check out that your filament is free all the time it is printing!

GeckospotNixie

Dshay
Never mind I now understand that you are talking about the current trim pot on the motor controller.
Got it
Thanks

I've got something like that when my extruder was extruding so much that the cooled off abs was obstructing the movement of the nozzle.

Since the print is quite small, what you can do is the sit and observe the print. See what is stopping the movement of the hot end.

Hi,

What's the voltage on your stepper drivers?
Are those polulu's?

Cheers,
Régis.

Hi,
Any news on this issue ? , i am facing the same issue too.. in my case, the first 2-3 layers are printed well, but start shifting after .. planning to swap x and y axis stepper drivers to see if the drifting layer shifts direction in Y axis...

Edited 1 time(s). Last edit at 05/16/2014 06:09AM by outlander.

Check the above answers !

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