Y-axis calibration failure, new kit - Assembly and first prints troubleshooting

RE: Y-axis calibration failure, new kit

hyiger — Wed, 24 Sep 2025 17:57:10 +0000

Also though in my case, I believe one of the belts is slipping in the harness which is why (maybe) I keep losing belt tension over time.

RE: Y-axis calibration failure, new kit

chmax — Wed, 24 Sep 2025 16:52:58 +0000

correct, I did read the comment and did that; my core one works rather well...

Posted by: @hyiger

Posted by: @chmax
There are indeed a few comments in the building notes on how many "teeth" of the belts need to be inserted in the holder. It is probably worth leaving a comment in the appropriate building step along the lines of "if you insert too may teeth this may happen:..."
Also, the number of exposed teeth for both belts need to be the same. If not (which was my case) I was having problems getting a proper belt tension which led to Y calibration failures.

RE: Y-axis calibration failure, new kit

hyiger — Wed, 24 Sep 2025 16:47:34 +0000

Posted by: @chmax
There are indeed a few comments in the building notes on how many "teeth" of the belts need to be inserted in the holder. It is probably worth leaving a comment in the appropriate building step along the lines of "if you insert too may teeth this may happen:..."

Also, the number of exposed teeth for both belts need to be the same. If not (which was my case) I was having problems getting a proper belt tension which led to Y calibration failures.

RE: Y-axis calibration failure, new kit

chmax — Sat, 20 Sep 2025 07:36:02 +0000

There are indeed a few comments in the building notes on how many "teeth" of the belts need to be inserted in the holder. It is probably worth leaving a comment in the appropriate building step along the lines of "if you insert too may teeth this may happen:..."

RE: Y-axis calibration failure, new kit

tabicat — Sat, 20 Sep 2025 02:36:58 +0000

I think I figured it out. I just needed a fresh look.

What I didn't understand is that the tensioner pulleys need to be retracted deep enough so that the gantry does not touch them. The gantry needs to touch only the motor mounts.

But if the belts are already pretty tight, then you will not be able to loosen them enough to pass the belt tightness audio test.

So my real problem is that belts are inserted too much into the Nextruder holder (step 5.51). Loosen them by 1 or 2 notches will allow me to retract the pulleys enough and still pass the tightness test.

RE: Y-axis calibration failure, new kit

AJ — Fri, 19 Sep 2025 17:38:06 +0000

Posted by: @chmax
Did you check if the cable of the sensor behind the right handle is interfering with the gantry's movement?

This happened to me. Turn the printer off (so the motors can free-spin) and slowly move the gantry along the same path it takes when it performs the Y-axis calibration (from the front-right corner to the back right-corner). Feel for any resistance at any point. Ensure the gantry isn't touching/squeezing/interacting with the sensor cable between the right handle and the back of the printer.

Diem — Fri, 19 Sep 2025 10:25:23 +0000

For *any* problem with a new printer or a new kit-build it is always best to go to Prusa Support via the Chat option; you will need your printer's serial number. Cheerio,

RE: Y-axis calibration failure, new kit

chmax — Fri, 19 Sep 2025 08:09:25 +0000

Did you check if the cable of the sensor behind the right handle is interfering with the gantry's movement?

This is a case where I would contact support via chat... it may take a long time but they usually manage to fix this kind of things...

RE: Y-axis calibration failure, new kit

tabicat — Fri, 19 Sep 2025 05:39:26 +0000

I've noticed that the failure X appears immediately when the gantry hits the rear of the printer. The Y-axis range is apparently -19mm to 210mm, so if there's an obstruction, I don't see it.

Y-axis calibration failure, new kit

tabicat — Fri, 19 Sep 2025 04:29:05 +0000

I just finished building my Core One kit, and the Y-calibration test failed. The belt tension is correct, and there is no gap on either side of gantry. I can move the gantry backwards and forwards, and both sides hit the ends at the same time. Perfectly aligned.

And yet, the Y-calibration is failing. I read in a lot of places that the T16-2GT geared pulleys might be inverted. How can I tell if they are?

Here's the left (X-Axis) assembly:

And here's the right (Y-axis) assembly:

Does this look right? Also, could someone post a video of what a successful Y-axis calibration looks like? I can only find videos of failures on Youtube.