Difficulty
Very easy
Steps
9
Time Required
00:30:00
User-Contributed Guide
This guide is not managed by the site's staff.
Introduction
If you cannot get your first layer to print after a QGL and you are always high on one side and low on the other you may have a twisted X extrusion.
Non-Teardown X Extrusion Twist Check (Values in parentheses are used only as examples and assume 300mm build)
Please remember to clear any mesh you might be running while completing this guide, as it will interfere with your ability to correctly measure the various heights in this guide.
Tools
Parts
No parts specified.
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Go to the center of the bed
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G0 X150 Y150 Z5
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Drop down Z slowly and touch a piece of paper.
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Record the Z value (ex 0.10)
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Move to the left side of the bed (X50) and keep the same Y (Y150)
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G0 X50 Y150 Z5
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Drop down and touch your paper.
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Record the Z value (ex 0.40)
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Move to the right side of the bed (X250 on a 300) and keep the same Y (Y150)
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G0 X250 Y150 Z5
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Drop down and touch your paper.
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Record the Z value (ex -0.15)
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You are now 0.30 (0.40-0.10) high on the left and 0.25 (-0.15-0.10) low on the right
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Formula (Recorded Z Value - Center Z Value) = Z offset
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Move to the front (Y50) and repeat the above at the same three X positions
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G0 X50 Y50
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G0 X150 Y50
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G0 X250 Y50
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Move to the the back (Y250 on a 300) and repeat the above at the same three X positions
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G0 X50 Y250
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G0 X150 Y250
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G0 X250 Y250
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If the Z offsets match for the same three X positions along the different Y values you have a twisted X extrusion - (or your bed is a perfect taco)
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Your sensor is correctly offset from your bed based on the Quad_Gantry_Level, but your nozzle is ~25mm in front. As you move along the twisted X extrusion the toolhead is rotating about the X axis swinging the nozzle in an arc. Moving along Y should not change this rotation.
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5 other people completed this guide.
2 Comments
It took me more than a year to realize that this was the issue with my 2.4. It was out by 0.1 from left to right. I verified that the beam rocked corner-to-corner on a flat surface. I twisted the beam with some clamps until it no longer rocked corner to corner. Its now within 0.04.
Moving the probe to be at the same Y offset from the X axis would allow this to be comped out with mesh bed leveling. I think this issue is a ringing endorsement for a force based probe.
Gareth Farrington - Resolved on Release Reply
This has been very helpful
I put together a quick Google Sheet to help those who are interested.
Stefan Van Biljon - Resolved on Release Reply
