New S3 XL: Z-Motor Limited to 30mm travel?

Hi All,

New S3 XL. Have been playing around and learning on some foam.

My Z-Axis is will only move downward ~30mm from 0 (limit) position. If you jog it from 0 downward (negative), it will stop at ~30mm. If you keep jogging it, the motor will still move in the increments sent, but there will be not movement of the axis: stays stuck at 30mm. On occasion, after about 5 seconds of continual Z- nudges downward, it sometimes will move past this point about 20mm more, then get stuck again. Moving Z+ is no problem. Works fine.

I checked the belts and pullies for obstructions: nothing. I verified the movement of Z axis is free and clear by hand with the power turned off. It really seems to be the motor. I also hear some clicking noises from inside the motor when moving Z manually by hand.

Is there a way to tell if the motor is pooched ? Best way to submit this to carbide support ? ?

First check the belt tension and the belt pulley set screws — if they’re okay, try removing one of the springs, if that doesn’t help, then you should check in w/

Have you checked that the set screw on the belt pulley is tightened against the flat spot of the shaft? My pre-assembled carriages had tight set screws, but they were not screwed against the flat spot. This resulted in things kinda-sorta mostly working in a “gremlins in there” way, with occasional slippage which looked kind of like the motors being weak.

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@mpfreivald Exactly. I figured out that it was the pinion set screws on the motor shaft: they were really loose (and no loctite!!!) So that’s a 14 h job down the toilet. Shout out to Union9: Throw some loctite on that shizzle.

Y-Axis had the same deal. All good now.

I had a similar problem early on. It seems that I had over tightened the V-wheels, and during the night they would develop a flat spot, which stopped the movement at one rotation.

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I wonder if anyone has an STL file for the plastic portion of the wheel ? Seems like a part that could be printed easily.

CAD and more information about the V-wheels at:


They take a fair bit of load, and PLA/ABS don’t have characteristics as well-suited for this sort of thing as Delrin.