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Left z-axis motor problems  

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duncan.c3
(@duncan-c3)
Active Member
Left z-axis motor problems

Hi, I've just finished building my Mk3 kit and have a problem with my left z-axis motor not turning - however, its a little weird:

If I plug both z-axis motors into the motherboard, then only the right motor turns, however if I plug either of them in individually, they both work independently. This is the same even if I switch the cables/connectors - when both plugged-in, only the right moves (I'm testing movement using settings/move axis/z-axis).

Anyone have any ideas what might be causing this?

The only thing I can think: the left motor/rod is a little harder to turn than the right, I assumed this was just caused by the weight of the x-axis motor - but I'm thinking maybe the drivers on the board might be detecting this as a jam and disabling power to the motor?

Posted : 29/04/2018 5:32 am
duncan.c3
(@duncan-c3)
Active Member
Topic starter answered:
Re: Left z-axis motor problems

I also forgot to mention: when the power is on, both motors are hard to turn - indicating power is getting to them both....

Posted : 29/04/2018 5:42 am
Gato
 Gato
(@gato)
Reputable Member
Re: Left z-axis motor problems

From the lcd menu you can see the motors voltage. What are the values?

Posted : 29/04/2018 6:37 am
duncan.c3
(@duncan-c3)
Active Member
Topic starter answered:
Re: Left z-axis motor problems

Update: I undid the trapezoid nut holding the threaded rod to the x-carriage, and the left motor now turns - so it appears to be that the friction of the trapezoid nut is too great and is preventing the left-hand threaded rod from moving up and down (when the I rotate the x-axis to the point where the trapezoid nut touches the orange x-carriage housing, the axis stops turning).

Has anyone else seen this? Can I get a replacement trapezoid nut?

Posted : 29/04/2018 6:48 am
Masher
(@masher-2)
New Member
Re: Left z-axis motor problems

I had a similar problem, but noticed it during assembly so I never actually powered up my printer.
It seems to me that it’s very easy to accidentally mis-thread one of the “trapezoid nut” (typically the left side where the x-axis motor is) when mounting the x-axis assembly onto the z-axis rods. These nuts come already threaded onto the z-axis and you have to unthread them and then re-attach them later in the assembly process. The nuts unthreaded easily in my case, but when I went to put the x-axis assembly onto the z-axis rods I mis-threaded the one side. I should have stopped when I felt the resistance and re-adjusted but I mistakenly pushed on thinking it would be OK. There have been a few other reports of this as notes on the assembly manual web pages.
I sent an email to support explaining the issue and after a little bit of back-and-forth to clearly identify which part I was talking about they have sent me a replacement. I will definitely be more careful when threading this new part and stop if there’s any hint of resistance.

Posted : 01/05/2018 4:08 pm
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