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Assembly Finished, Startup Errors, Z-axis Stiff  

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RivCA
(@rivca)
Active Member
Assembly Finished, Startup Errors, Z-axis Stiff

So, as the title says, I just finished assembling my kit, but the left Z-axis screw is so tight  that it's keeping the motor from turning. During assembly, I checked and rechecked quite a few times to make sure I wasn't cross-threading the trapezoid nuts, but it still kept going on stiff. I thought this was just due to the left motor needing to be stronger than the right motor as it has to support the X-axis motor, but now I'm seeing that's not the case.

First off, would switching the trapezoid nuts around alleviate this? If that's not the case, do I order new ones?

Posted : 15/12/2019 11:54 pm
rmm200
(@rmm200)
Noble Member
RE: Assembly Finished, Startup Errors, Z-axis Stiff

The trapezoid nuts are delivered on the rods so Customer Support knows they turned freely when delivered.

If you try to install the nut after it is attached to the bracket - you will cross thread it. Nut on rod first - then screw it to bracket.

I cross threaded one of mine, and had no luck convincing Customer Support it came that way. I ordered a replacement set from China.

While waiting, I took the nut and servo off, and worked the nut up and down the threaded shaft. It is Delrin - it will form under pressure.

Eventually, it worked smooth enough to put it back in service. I use that nut to this day - with no Z failures ever.

My China spares look good - but they sit waiting until the day they are needed.

Posted : 16/12/2019 12:48 am
RivCA
(@rivca)
Active Member
Topic starter answered:
RE: Assembly Finished, Startup Errors, Z-axis Stiff

Good to hear. I just worked off both nuts and switched them with each other, and the one that turned freely out it the right shaft did so on the left shaft. The one from the left shaft is stiff on the right. I'll have to work the shaft against the nut for a few cycles, if that's the case. It's not cross-threaded, but it's still stiff enough to keep the motor from turning.

God, I just realized that this could look like the setup for a bad porno.

Posted : 16/12/2019 1:05 am
RivCA
(@rivca)
Active Member
Topic starter answered:
RE: Assembly Finished, Startup Errors, Z-axis Stiff

...and the headache continues. Every time I've run the cal wizard, it faults out when trying to perform XYZ calibration. This guy had the same problem, but I don't see a solution. Unless I'm blind or a complete idiot, the solution is insidiously hidden from where I can find it.

Does anyone even have a Bleep solution?

Posted : 17/12/2019 6:16 am
RivCA
(@rivca)
Active Member
Topic starter answered:
RE: Assembly Finished, Startup Errors, Z-axis Stiff

Sorry. I'm just mad. There's nothing quite like using your own skull to knock down a wall.

Posted : 17/12/2019 11:59 pm
RivCA
(@rivca)
Active Member
Topic starter answered:
RE: Assembly Finished, Startup Errors, Z-axis Stiff

Finally!

OK, anyone else beating their skulls in over this, my answer was to run a factory reset.

To do that, press the reset button (the cutout with the X on it) and quickly press and hold the control knob after resetting. Hold until your machine screams bloody murder (about three seconds) then go from there.

Posted : 18/12/2019 1:23 am
Edmond
(@edmond)
Active Member
RE: Assembly Finished, Startup Errors, Z-axis Stiff

I just finish the assembly, and got the same problem. So..any resolution, please?

Posted : 28/12/2019 9:07 am
rmm200
(@rmm200)
Noble Member
RE: Assembly Finished, Startup Errors, Z-axis Stiff
Posted by: @edmond

I just finish the assembly, and got the same problem. So..any resolution, please?

Same as above. Check your nuts. Take the screws out of the trapezoidal nuts (no need to disassemble anything).

Make sure each one turns freely. If one is stiff - work it on the shaft until it is free. Or replace it.

Posted : 28/12/2019 4:34 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Assembly Finished, Startup Errors, Z-axis Stiff

I had the same problem and did not want to rework anything to ensure the precision and therefore bought a set as a replacement and one as a  reserve.

https://shop.prusa3d.com/de/ersatzteile/682-trapezoid-nut.html

or

https://www.aliexpress.com/item/32860620795.html?spm=a2g0s.9042311.0.0.27424c4dBvnJ6F

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 30/12/2019 1:27 am
ocalld
(@ocalld)
Active Member
RE: Assembly Finished, Startup Errors, Z-axis Stiff

I've had issues with Z axis. 

When I origonaly assembled the printer it calibrated fine. Within 4 prints It failed and the left z axis rod was very stiff to turn. this meant the right side z axis would run faster and calibration fail. 

Spoke to Support who sent me a new motor. put it together and had the same issue. 

It turns out that the black printed part that you fit to the threaded rod that goes all the way to the bottom of the rod and against the motor (think it's to stop debris getting into the motor), well this was catching and causing the threaded rod to stick. 

I just unwound it slightly, maybe half a flat and issue resolved. 

 

cheers

dan 

 

Posted : 01/10/2020 12:11 am
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