Cannot get Mesh Bed Compensation to work correctly
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@alijambo73
From my own experience I can say that a original HEVO Z-axis does not work properly (and my bed is only 350x350...).The bed frame is not stiff enough. I had to constantly relevel the bed.
I modified the connection of the linear bearings on mine.
https://forum.duet3d.com/topic/13530/za-and-zb-connections/21?_=1651794964325
Maybe your third z-axis makes a little difference. -
@diy-o-sphere Did you have the same issue with Mesh Bed Leveling and did this solve it?
I run a g32 so the bed should technically be level so I kind of ruled that out.
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@alijambo73 said in Cannot get Mesh Bed Compensation to work correctly:
I have linear rails not rods and they seem to perfectly parallel.
How did you determine that?
Frederick
Printers: A FT-5 with the 713 upgrade bits, a custom MarkForged style, a small Utilmaker style, a small CoreXY from kit and a E3D MS/TC setup. Various hotends. Using Duets (2 and 3) running 3.4.6
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@fcwilt said in Cannot get Mesh Bed Compensation to work correctly:
@alijambo73 said in Cannot get Mesh Bed Compensation to work correctly:
I have linear rails not rods and they seem to perfectly parallel.
How did you determine that?
Frederick
By feel
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@alijambo73 said in Cannot get Mesh Bed Compensation to work correctly:
2.235, 2.22, 2.132, 2.068, 2.027, 2.015, 1.985, 1.905 and 1.885.
The fact of the matter is your probe trigger height is varying quite a bit at different locations.
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@alijambo73 said in Cannot get Mesh Bed Compensation to work correctly:
How did you determine that?
Frederick
By feel
You are making a joke?
Frederick
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@alijambo73 said in Cannot get Mesh Bed Compensation to work correctly:
Did you have the same issue with Mesh Bed Leveling and did this solve it?
I had inconsistent z movements. When the printer was moved in Z, it did not return to the previous height.
It was easy to measure with a gauge. This was most noticeable in the corners. The bed mechanics was always bent. After the rebuild, there are no more problems with that. -
It's possible that you have gantry twist which would explain the different trigger heights. In theory you could write a bed.g which adjusts the trigger height depending on location but that sounds weird.
To find out whether you have gantry twist it probably is best if you used a dial gauge to measure rather than feel the distance from gantry to bed. Since your gantry and rod fittings are 3d printed they allow for a bit of compliance. Adding some bushing slop and possible ovality of your rods can easily make for half of your measured differences, and a slight twist which I don't think would be visible to the naked eye or feel will not show up by moving the gantry since the compliance of the printed part will allow the mechanism to slide without interference.
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no idea why this was addressed to DIY-O-Sphere, it was supposed to go to OP of course.
