Random / Occasional FRUSTRATING Axis Slips

I have a Prusa I3 that is still new to me since the beginning of this year. It went through a period of printing stability and still has its moments.....until an axis decides to randomly slip or skip. I have been working on this for weeks and have tried everything that I can find on this board (at least I think)! As I said, the printer will have moments of stability where it will print for hours with no issue and pretty good quality. The X-axis is the favorite to slip but the Y and Z will occasional join the fun. It does not always happen on a long print as it has been known to happen early in a print as well.

Here are the things that I have tried and/or ruled out:

• I have adjusted the trim pots from just over stall to a quarter or more turn past stall
• I have swapped stepper drivers
• I have moved the x-axis to the second extruder slot
• I have upgraded power supplies
• I have added a big cooling fan to the electronic stack
• I have ensured that my timing belts are not slipping
• I have made sure that the carriages move with minimum resistance
• I have slowed everything down when I slice the part

What else is left to try?!?!? Could it be the Ramp board ... or the Arduino? They are the only things that I have not replaced or been able to rule out!

Wisar

Maybe EMI from somewhere if it affects all axes?

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Waitaki 3D Printer

Interesting idea but what would the possible source of the EMI be in a home office environment and how does one protect against it? On a similar line I was wondering if my AC power was clean. Wonder if a UPS inline to the printer would help?

[Update] Have connected printer to 1000W power regulator and am doing a print that has not finished to date. Is past points of two previous failures but not done, and not the third.
[Update] Printed the whole part that had been failing. Still not conclusive as the printer has had times when it has run without psychotic episodes for a while before throwing a fit. Only change was AC power conditioning.

[Update] FRUSTRATION RETURNS. Small slips on the two parts after the part that finished ok! Argh. I really don't want to dissassemble all the electronics to replace the Ramps board but that is the next step unless someone can steer me in another direction.

Wisar

Edited 3 time(s). Last edit at 03/13/2014 11:53AM by Wisar.

Have you adjusted the voltage on the pots?
Have you got heat sinks on all the pololu chips?

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Waitaki 3D Printer

Waitaki:

I have run the pots at a variety of settings from 1/8 turn above the stall point, to 1/4 turn above the stall point, to a 3/8 turn above. The voltage at 1/4 turn is .25, .25. .87, .61 (x, y, z, ex). All the steppers have heat sinks and I have a mongo cooling fan running on top in addition. I don't feel anything particularly hot when this occurs.

I have now swapped out the Ramps board and while I have not had a slip again...I have also not had time to print something reasonably large. Later today will try for something largish.

Wisar

Edited 1 time(s). Last edit at 03/14/2014 04:22AM by Wisar.

Hopefully final update. Just finished a seven hour print with no slips. Am assuming that it was the Ramps board and that, hopefully, it is going to be ok now.

Wisar

What does your wiring look like? Some of the pictures I see make me hungry, looks like spaghetti! For those of you still building a printer a word of advice. 'Cleaning up the wiring' is NOT something you do at the end! Routing wire neatly starts at the beginning and continues through the wiring process. Use lots of wire ties, buy they cheap ones too, as you should be tying the wires in place as you go and often cutting the ties off as you add more wires. These are my control cabinets, not as neat as I'd like as they are a little small and the shielded cables are quite large.

I wonder if the act of replacing my Ramps board might well have reseated a loose connection in my wiring...which is closer to a bowl of spagetti than to your example. Future project to clean up the wiring...

Wisar