Duet 3 SBC : Need explanation on multi Z homing
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@dhusolo Hi, why do you do the homing/probing 3 times ?
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Multiple runs help to see that the process converges.
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@oliof but how ?
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In most cases, lead screw positions are approximated so adjustments aren't perfect
In my case, after the the first adjustment, I run again and see a smaller adjustment. I.e. in the first run 0.5mm, and in the second run 0.03mm. Whith the third run there usually is no tilt to adjust for anymore since the remaining difference is less than the resolution of the z probe.
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As a side question to this.
Say you are using a kinematic 3 point bed; do you specify the leadscrew positions as where the leadscrews physically are, or where the kinematic pivot is? It would seem that in this situation, you would want to specify the pivot point, then probe as close to those locations as possible?
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@NexxCat said in Duet 3 SBC : Need explanation on multi Z homing:
you would want to specify the pivot point, then probe as close to those locations as possible?
Yes, that makes sense. However, in practice, it isn't really critical because you're likely going to run 2 or 3 cycles anyway to make sure it's converged, however the closer on the first pass the better.
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@Phaedrux said in Duet 3 SBC : Need explanation on multi Z homing:
@NexxCat said in Duet 3 SBC : Need explanation on multi Z homing:
you would want to specify the pivot point, then probe as close to those locations as possible?
Yes, that makes sense. However, in practice, it isn't really critical because you're likely going to run 2 or 3 cycles anyway to make sure it's converged, however the closer on the first pass the better.
Perfect, thanks!
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@NexxCat I had better results with the pivot point vs the leadscrew position and probe as close to it as possible
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Where you probe doesn't matter if the bed is flat, although obviously measuring the tilt is more accurate if the probe points are widely separated.
You can probe more points than you have leadscrews.
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@dc42 said in Duet 3 SBC : Need explanation on multi Z homing:
Where you probe doesn't matter if the bed is flat, although obviously measuring the tilt is more accurate if the probe points are widely separated.
You can probe more points than you have leadscrews.
So you could, for example, probe a 3x3 over the entire bed (9x G30 probe points) and still use S3 on the final one to have the three lead screws correct based on a larger data set?
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@NexxCat said in Duet 3 SBC : Need explanation on multi Z homing:
@dc42 said in Duet 3 SBC : Need explanation on multi Z homing:
Where you probe doesn't matter if the bed is flat, although obviously measuring the tilt is more accurate if the probe points are widely separated.
You can probe more points than you have leadscrews.
So you could, for example, probe a 3x3 over the entire bed (9x G30 probe points) and still use S3 on the final one to have the three lead screws correct based on a larger data set?
To answer my own question. You can indeed do this!
