Probe offset...?

[Marco Robustini]

Hi, i put the coordinates of my BLTouch inside the config.txt, but I see that during the automatic calibration is not considered, i mean at "hardware level".
With other firmware like "Repetier" during probing the BLTouch it's centered with respect to the printer geometry, with Smoothieware remains centered the nozzle... is normal?
The offset of the probe so why need to be assigned? For a calculation that then executes the code?

leveling-strategy.delta-grid.probe_offsets         24.25,-14,0     # probe offsets x,y,z  (Z should always be 0)

Marco

[wolfmanjm]

that should mean that the probe is 24.25mm to the left of the nozzle, and 14mm in front of the nozzle.

Check with M503 look for the M565 line and make sure they are set correctly. (they are overidden by the config-override file if you have one.

If set correctly you need to reduce the size of your probe area by at least 25mm in the X direction obviously.

What it will do when probing is offset the position by that much so the probe is centered, however for delta grid this will totally screw up the accuracy of your results, as explained in the wiki.

Delta really need the probe centered as close to the nozzle as possibel due to the way the geometry works, so your results will be suboptimal

[wolfmanjm]

Sorry I mean that it means the proibe is 24.25mm to the right of the nozzle. so this means that the head will have to go 25mm further out than normal at the edges so you need to reduce your probe diamerer by at least 25mm

[wolfmanjm]

NOTE G29 does not apply the probe offsets, only G31

On Monday, April 17, 2017 at 3:05:22 AM UTC-7, Marco Robustini wrote:

[Marco Robustini]

Yes, is front/right, and the line in the config-override is correct:

M565 X24.25000 Y-14.00000 Z0.00000

Marco

[Marco Robustini]

This is my little delta, here the probe is "front/left".
As you can see in Repetier when probe the third of the five lines it's centered on the X axis:

https://www.youtube.com/watch?v=MPdJW-fVP-E&t=14s

Marco

[wolfmanjm]

Then it will work presuming you set the radius correctly to account for the offset. But as I said it will not give good results if you are trying to correct for delta geoemtry errors.

There is nothign you can do about that as it is part of the delta kinematics. it is explained here... http://smoothieware.org/zprobe#configuration1 see the NOTE about it.

If you set the offset then it will probe where you tell it to probe, I am not sure what else you expect it to do.

Repeteier probing s NOT anything like smoothie so do not expect the same results wrt behavior.

Smoothie probing s more like the Johan Rochol version of Marlin probing.

[Marco Robustini]

Ok Jim, all clear, thank you!
What do you plan to implement this method in the future?

http://escher3d.com/pages/wizards/wizarddelta.php

MKDuo (MarlinKimbra) use this one, all automatic, with "G30 A" command.
Another suggestion: sometime with my original BLTouch i've this message during "G32":

Probe was not repeatable to 0.030000 mm, (0.040009)

I think it happens because the probe carries two touches and compares them, if the error is greater than that allowed aborts the procedure.

So I think it's possible that this error may elapse during other touches.
So why not add the ability to run a "multitouch" comparison on other calibration points, as in the first?

Marco

[wolfmanjm]

no plan to implement that hack :)

Grid is much better IMO, grid only corrects areas that need correction that least squares hack basically spreads error over the bed so it reduces in one area but introduces error in an area that has no error, I don' t like that scheme at all, so have no plans of implementing or accepting implementations of it.

If you really want that then there are third party branches that have similar hacks.

Sorry :)

Your other questions are answered on the wiki so please read that.