Y Axis Freaking Out Randomly - Mendel

I'm working with a Mendel that I bought pre-built, supposedly working. I set it up to use Repetier Host and Repetier Firmware.

I got all the settings in the firmware correct so that all 3 axes move smoothly, in the correct direction, the correct amount, and they all home properly to the installed endstop switches (mechanical switches).

I verified that it runs fine multiple times by using the manual controls to jog and home repeatedly, and I was able to do my first test print, which was ugly, but showed that everything was functioning well.

NOW... it starts freaking out. Suddenly the Y axis:

• Refuses to move in the - direction
• Only moves in the + direction
• When I try to home it, it moves only about 3 mm in the Wrong.Direction
• When I try to home it, it moves much more slowly than it should, and quite noisily.

It has happened more than once, and a couple of times it seemed to clear up when I re-uploaded the firmware, but I think that was just random chance. All indications are that the firmware and config are fine. It just seems to decide to get f@*&(#ed up for no particular reason.

I feel it is likely a hardware problem, but I don't know enough about this thing to know what to check. I would appreciate any suggestions as to what tests or other I can do to try to isolate this problem.

Setup:

Mendel with Arduino Mega 2560/RAMPS 1.4
Windows XP (I know, I know...)
Repetier-Host (latest version)
Repetier Firmware (latest version)

TIA.

Sounds like your y endstop has a dodgy connection.

Actually, the endstop switch had died altogether. It's an SPDT so I wired it the other way around, switched the logic in the firmware and voila! I'm making crappy prints again!

Now I can focus on making the quality right instead of goofing with the darn machine.

Thanks for the pointer, James

Brian-

I would also check the motor connections - if one wire is missing or has a bad connection it will do what you describe. And if you have already found one dodgy connection I would be checking the rest. Then again, if it aint broke don't fix it

Edited 1 time(s). Last edit at 10/21/2012 05:27PM by Wired1.

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Richmond, New Zealand
Thingiverse ~ YouTube

Yes, I think the machine deserves a good looking over when I get a chance. I'm also developing plans to do some re-wiring and re-positioning of the electronics for convenience and reliability, but for now I'm just pumping out test parts in an attempt to get my brain wrapped around the subtleties of 3D printing.

Fun!

B-

Along those lines, I also had an issue when the stepper wires were bundled with the endstop wires. There was crosstalk that was creating false endstop events randomly.

-Rob A>