Shifting layers

Hi guys,
Sorry to bump in right at the start with a question, but I have exhausted any other resource to my knowledge and I really need some advice. If I made some mistakes please just be patient and tell me.

I have tried to build my first 3d printer and opted for a Prusa I3 from kitprinter3d, a spanish reseller. I selected it because I believed the metal frame would add precision to the prints. I run it with an Arduino 2560, a RAMPS 1.4 board and I have tried both A4988 and DV8825 drivers to get it to work. I have used the Merlin firmware downloaded from the link provided by the company on the Arduino (which have, according to the page, different settings for the two kind of drivers).
I'm using a Catnozzle extruder (0.3mm) with a 3mm filament feed.

I've use Slic3r to get the gcode, and pronterface and Repetier host as programs, and Cura as well (both to get the gcode and run it) to get the prints.

The issue is that the X and Y layers get shifted. I have tried to look into this forum to get some answers, but I cannot seem to find the right ones: I have set the drivers' pots to the exact specifications I found on the website: 0.5 for both X and Y, 0.8 for Z and 1.0 for the extruder. I have installed heat dissipators on every driver and a fan over the board to cool it, so it shouldn't be a temperature problem.

I always get a print to start but the layer shifts after a little and the print looks like a lopsided pile of dishes. I've attached a picture of one of my prints.

My sincere thanks

"I just mounted a DRV8825 driver onto my RAMPS board and I found no problems with my extruder.
I have a homemade 3D printer with a direct-drive extruder that havent enough torque to feed my filament. So I installed a new stepperdriver. Before I installed my new driver, Ive studied Pololu documentations and I find something that would ( maybe ) help you guys!

I noticed that: - nobody mentioned about the wiring schematics for your new driver DRV8825 to your bipolar motor.

example:

with the "old" driver ( A4988 ) you have 2 sets of wiring that energize your steppermotor.
==> 2B and 2A, Blue and red. and the others ==> 1A and 1B, green and black.

with the new Pololu driver ( DRV8825 ) you have also 2 sets of wiring. But different then above!
take a look: ==> 1B and 2B, Blue and red. and the others ==> 1A and 2A, green and black.

Result: old driver wiring setting is not compatible with new one. So verify if your wiring is comform specification connected.

Because if your wiring is not properly connected to you hardware. Then it will cause a problem.
Each motor has his 2 coils. And 1 coil has 2 wires = 2 x 2 =4 wires. Can you imagine when mixing up these wires? Nothing will happen. Steppermotor won`t do a thing.

Make sure: Pot-resistor is turned to a minimal.
And make sure that: your jumper setting is set to FullStep for fine adjustments with your POT-resistor."

Just pasted this info from another post, if using the DRV 8825 be on the look for the issue explained above

Hi thanks for the tip, but unfortunately this does not solve my problem: I have tried both A4988 and DRV8825 drivers, with the appropiate jumper positions and pot settings, but the problem remains.

You see, apparently the layers are fine, it's just that they "stack" incorrectly, the starting point drifting from the correct position...

Then either your steps per mm are wrong for the failing axis or you have a loose belt or pulley

Quote
ggherbaz
Then either your steps per mm are wrong for the failing axis or you have a loose belt or pulley

yes, and most likely the latter. If your steps per mm were off, the effects would be linear, not random. Check for loose belts, binding, etc.

Edited 1 time(s). Last edit at 11/12/2014 11:57AM by jbernardis.

So, I've decided to dismantle the X and Y axes and rebuild them from the bottom up... It was a chore, but it paid off: the printer works now.

Thanks for the help guys, I'm truly grateful.