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Self Test fail: X and Y pulleys different?  

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Dave
 Dave
(@dsm)
New Member
Self Test fail: X and Y pulleys different?

I've just finished assembling my Prusa i3 Mk3S and it failed the Self Test with the dreaded "Axis Length X" error.

The X axis appeared to move freely from end to end.  I checked all the usual culprits - obstructive zip ties and wires, belt tension, screw tightness on the X-carriage-back and none of them fixed it.  I even tried XYZ calibration but the Pinda ended up off the side of the heatbed so the X axis was obviously way off.  I tried the "Move X" function and found that the axis went from 0 to 220 end-to-end which meant it was significantly shorter than expected.

I came across this post which mentioned that somebody had X and Y axis pulleys that were different diameters.  I assume "GT2-16" means it should 16 teeth: my X pulley has 25 teeth (see pic). X axis pulley - 25 teeth

I swapped the pulleys over from the X and Y axes and the X axis test now passed.  Now the Y axis test fails on axis length and, when I try Move Axis, it also only goes up to about 220.  This pulley must have too large a diameter.

My conclusion is that the smaller pulley (the one originally on the Y axis) is the correct one for both X and Y axes.

The manual calls them both "GT2-16" pulleys so they should be identical.  Did I just get the wrong pulley in my kit?

This topic was modified 2 years ago 2 times by Dave
Posted : 08/03/2020 11:12 am
JoanTabb
(@joantabb)
Moderator
RE: Self Test fail: X and Y pulleys different?

yes!
have a word with support, on 'Chat' on the eShop page

 

regards Joan

 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK...
Posted : 08/03/2020 12:01 pm
Dave liked
Dave
 Dave
(@dsm)
New Member
Topic starter answered:
RE: Self Test fail: X and Y pulleys different?

The 16-tooth pulley on my X axis works well.

I ordered a cheap 16-tooth pulley to test the Y axis and that doesn't seem to work.  On "Move Axis" my Y axis now goes from 0 to 216.

Can you please confirm how many teeth my Y axis pulley should have?

Thank you,

Dave

Posted : 09/03/2020 8:44 pm
Knickohr
(@knickohr)
Moderator
RE: Self Test fail: X and Y pulleys different?

Both, x and y, are 16T pulley. But be careful, don't mix GT2 with 2GT pulleys and belts !

Thomas

Posted : 10/03/2020 9:00 am
rmm200
(@rmm200)
Noble Member
RE: Self Test fail: X and Y pulleys different?

Both tooth number (must be 16) and tooth profile are important.

If you wrap your belt half way around the pulley, the teeth on the belt should be a perfect match for the teeth on the pulley.

Posted : 10/03/2020 3:38 pm
Texy
 Texy
(@texy)
Reputable Member
RE: Self Test fail: X and Y pulleys different?
Posted by: @dsm

The 16-tooth pulley on my X axis works well.

I ordered a cheap 16-tooth pulley to test the Y axis and that doesn't seem to work.  On "Move Axis" my Y axis now goes from 0 to 216.

Can you please confirm how many teeth my Y axis pulley should have?

Thank you,

Dave

IF you bought the kit from Prusa then as Joan pointed out, you only need to speak to live chat - they would arrange a free replacement, so you didn't need to "ordered a cheap 16-tooth pulley ".

Texy

Posted : 11/03/2020 12:28 pm
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