Geeetech Aluminum prusa Z-axis slipping

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Geeetech Aluminum prusa Z-axis slipping

Post by schalkvstaden » Fri May 12, 2017 12:13 am


I have just finished by aluminum i3 and have got some problems. After leveling the z-axis it seem that when i move the z axis up or down sometimes it seem like one of the stepper motors slips or move faster or slower causing the z axis to be misaligned. one side being higher than the other. any one with this problem and sollution?

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Re: Geeetech Aluminum prusa Z-axis slipping

Post by Soadyheid » Fri May 19, 2017 11:24 pm

What have you tried so far?

Is the Z_axis binding at either side? Are the vertical straight rods, er... straight? If there's binding, one of the motors will stall which will cause the binding to get worse.

Are the motors plugged in firmly, no faulty cables?

Have you tested each Z_axis motor by connecting them, one at a time, to a different axis, say... X then moving the X axis? (You'll need to remove the Z-axis motor under test from the printer first obviously.)

You can also swap the driver daughter boards between axies to check they're OK as well. Check the Vref of the Z-axis driver is somewhere about 0.8v which translates to 1Amp through the motor coils. (normal setting) Don't take it higher than 1.6V = 2 Amps which is a bit high and can cause overheating problems even though the motors have more power.

You should now have checked the motors, cables and driver boards and hopefully found the problem?

Play Bonny!


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Re: Geeetech Aluminum prusa Z-axis slipping

Post by atgaskins » Thu Jun 01, 2017 7:20 am

How much are they getting off? I occasionally use my calipers to get them back a matching height (measure between the bttom of brass threaded piece and the top of the acrylic z motor mount plate). But this is usually just a mm of offset after a dozen prints or more (less if I'm doing particularly tall prints like a vase maybe). And I've never really noticed an issue from it in my prints, it's just more of a perfection thing. I assumed this was normal accumulation of the minor differences in the motors, but maybe it's something else... my rods are oiled and free-floating in about a 3/4" hole at the top (I've found that I get smoother printes if I don't try to force the z-rods straight, the smooth rods do that just fine). But yeah, if your getting more than that you have a bit problem. When I first build my Pr C the holes at the top were waaaay to snug on the threaded rods, so it took some work just to get them turning at all before I actually fired the printer up initially, and then I would oil the rods and that area at the top... which all led me to just printing new top plates that left a large space around the threaded rods. Run the heads all the way up and watch & LISTEN closely for anything suspicious. You might want to free your rods as I did, I am much happier with prints. I still calibrate the level of the X-carriage on the z-rods though, I don't know how to get them to not drift at all, and but I assume your talking about a bigger problem.

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