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I inherited a problem 😀  

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caleb.p3
(@caleb-p3)
Active Member
I inherited a problem 😀

Mind you a good problem to get for free yet still a problem I intend to fix.
So I have received a gift from a co-worker who struggled to ever get his prusa i3 mk2 to calibrate.
He was ready to run it over with his truck. 😀
So I grabbed my calipers and started in on the manual to dial it in.
I was able to get it to calibrate but only when I intervened.
The z-axis motor on the left ever so often will notch up a slight turn while the right one never rises.
So if I twist the right one at when the left one goes the calibration completes.
Otherwise it fails.

Is the left one supposed to be twisting a little ever 30 seconds or more and the right one isn't doing it's job or the other way around?

Unsure what's causing it but it causes my prints to fail as well.

Thoughts?

Posted : 01/06/2018 7:30 pm
john.v11
(@john-v11)
Estimable Member
Re: I inherited a problem 😀

They should both move at the same time. Make sure the black cone nut is not to tight or binding.

Posted : 01/06/2018 8:42 pm
caleb.p3
(@caleb-p3)
Active Member
Topic starter answered:
Re: I inherited a problem 😀

It's not tight or binding it's able to calibrate Z just fine and move without skips or studders.
I am able to do flat prints pretty well but taller ones always fail due to this issue.

I'll try and grab a time lapse video of it and post the link here in the forum to clarify the issue.

Posted : 02/06/2018 12:46 am
PJR
 PJR
(@pjr)
Moderator
Re: I inherited a problem 😀

Some Mk2 printers had an issue with the cables; when the motor was attached, the cables were crushed against the frame and this caused intermittent/low power motor operation.

If you remove both motors and turn them so that the cable outlets are pointing towards the centre of the printer, that may help, but you may need the cables replacing if they are badly damaged.

Another possibility is at the RAMBo end. The small metal connectors at the end of the wires sometimes push out of the plastic holders, again creating a poor connection.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 04/06/2018 2:48 pm
caleb.p3
(@caleb-p3)
Active Member
Topic starter answered:
Re: I inherited a problem 😀

I tried the timelapse to show it's stepping but it doesn't really show what I wanted and still trying to get a print and video that shows off the slight shifting in the print. Here is a couple of photos of a failed print due to this issue though..

https://photos.app.goo.gl/inwDi2Ft8kdgMAJH7

I've check the wires to the "ticking" motor and looked for damage. I don't see any visible damage but I did take the advice and rotated it so the cords don't go under the printer but just to the side instead.

Attempting calibration now and seeing if it's still ticking.

Posted : 28/06/2018 6:51 am
caleb.p3
(@caleb-p3)
Active Member
Topic starter answered:
Re: I inherited a problem 😀

Got a video of it ticking by zooming in a ton and hopefully it shows what i'm talking about.

https://photos.app.goo.gl/S7BDDjS8Rn4swk1MA

The left ticks while the right doesn't at all during this last calibration attempt

Posted : 28/06/2018 6:59 am
PJR
 PJR
(@pjr)
Moderator
Re: I inherited a problem 😀

Yeah, still looks like a cable/connector issue. Or it could be the small printed black plastic cover at the bottom of the lead screw too tight.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…...
Posted : 13/07/2018 12:12 pm
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