Bltouch does not probe the whole bed

Hello all
I use duet 2 wifi with elder 3 and original bltouch. I did manage to wire everything together and it works. The only issue I have is a bltouch not willing to probe the whole bed.
I have correct set of values for X, Y, Z size bed. Bltouch offsets are done also. So when the bltouch probes the bed, it surely stops at the offset value so the hot end does not go beyond the bed size and hence I have the chunk of bed not probed. I do understand the logic, but I see no use in a probe if I can not probe the whole bed. Am I missing something ?. Is it normal not to probe the whole bed because bltouch is offset from the hot end and hot end will not go off the bed.
Thank you for your time.

When you run mesh probing, do you get warning messages that points were not probed because they are not reachable?

If yes but it is mechanically possible for the probe to reach those points, then either you have not set the probe XY offset correctly in G31, or your M208 settings for the area reachable by the nozzle are too small.

If no, check the M557 command that defines the area to be probed.

Edited 1 time(s). Last edit at 08/04/2019 02:05AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Indeed I get this message often. I will look into those commands . At this point I want to confirm, that duet allows the nozzle to go off bed .

Edited 1 time(s). Last edit at 08/04/2019 07:30AM by Romantch.

The firmware on the Duet will allow the Hear Reference Point (which is normally the nozzle in a single nozzle machine) to go as far as you say it can in the M208 command in config.g.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I messed with the printer the whole evening yesterday. Still no luck. My problem is as follows. Consider X size 220mm. Probe offset -42mm, so for the probe to probe bed at 219mm, the nozzle has to go off bed 219+42. Hence duet throws an error- probe can not reach point. I could increase X which now will reflect gantry size and not bed size, but I am afraid running into problems later, printing off bed. I had bltouch installed on marlin 1.1.9 and do not remember having any problems. Somehow marlin thinks it is ok to go off bed. At loss here.

Quote
Romantch
I could increase X which now will reflect gantry size and not bed size, but I am afraid running into problems later, printing off bed.

That is the correct solution. If your slicer is correctly configured then you won't print off the bed - but if you make a mistake, does it really matter if the hot end extrudes when the nozzle is not over the bed? It's common on some machines to prime the nozzle in an areas off the bed anyway.

If you really want, you can use a macro to change the M208 axis limits depending on whether you are printing or mesh bed probing.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks a lot for your help. Using the whole axes did solve my problem. I thought bltouch would use offsets to validate whether it is still on the bed, but I guess it is only using offsets while creating a mesh. Anyways, I am back to printing.