[FR] G29 P1 with automated supend

[mpheyse]

Is your feature request related to a problem? Please describe.

I've been making our older larger printers work like our newer small Bambu printers.

Specifically where a UBL process is run before each print, not loaded from eprom.

During the G29 P1 (which takes about 8+minutes) I keep the Bed at temp but run the Hotend off or at half temp.

Having the Hotend fully up to temp, oozes too much over the long P1 Cycle. So I've gone to running it a half-temp, so that that there isn't as much ooze and not as much wait-time after UBL to heat up the Hotend.

What I would like to do is start the full Hotend heat cycle at the last 2,3, or 4 (actual) probe points. So that it heats while the end of probing is happening.

We use the BL-Touch probes so Hotend temp does not effect a P1 cycle.

Are you looking for hardware support?

Not Hardware specific.

Describe the feature you want

Allow users to break up (suspend) the G29 P1 probe cycle via G-Code, so commands can be run during the probing process.

This suspension already manually available by physically holding the button, then G-code [C] continuing.

So I want G29 P1 to optionally take a variable (like [R]) that will Probe 'R' points then stop (suspend mesh generation) automatically like a user held the button, at send point.

Then I can issue a M104 for what I need

and then Continue Probing using G29 P1 C

Even better for me would be such that 'R' can take negative points, where
G29 P1 R-4 would probe the 4th-to-last point and then stop/suspend

I'm suggesting using [R] as it exists already for G29, but isn't used for P1, and is a 'point count' sort of, already

Additional context

Examples
G29 P1 ; Existing function, probes all points, till the end unless manually stopped
G29 P1 R4 ; probes first 4 points, then stops/suspends
G29 P1 R4000 ; probes likely all points as the R exceeds the full point count
G29 P1 C ; Existing function, continues where probing left off, till the end unless manually stopped
G29 P1 C R4 ; probe the next 4 points, if there are 4 points left. otherwise just probes the remainder
G29 P1 R-4 ; probe first point thru to the 4th-to-last point, inclusive
G29 P1 C R-4 ; probe next point thru to the 4th-to-last, inclusive. BUT If we're already past 4th-to-last probe point already this command does nothing.

So for my use I would use
M190 S70 ; Heat Bed and Wait
G29 P1 R-4; Probe all but the last 3 points
M104 S255; Heat Hotend, No-Wait (i.e. start heating three points before the end)
G29 P1 C ; Probe all other points
G29 P3 ; Fill unreachable points due to head travel
G29 A ; Activate UBL System
M109 S255; Heat Hotend, and wait (if we weren't already up to temp by this time)

Final note as I'm specifying R-# is an inclusive count.
G29 P1, G29 P1 R-0 and G29 P1 R-1 are functionally the same command
like wise
G29 P1 C, G29 P1 C R-0 and G29 P1 C R-1 are functionally the same command
also
G29 P1 R0 and G29 P1 C R0 just do nothing (probe zero points)

[Nuck-TH]

Sound too complicated for niche use case tbh
Also, if you are fine with 8+min of probing(just how many points you do. huh?), them surely print can wait one more minute for hotend to heat up.

Btw, mapping before every print is not needed with good Z endstops/probe and sound mechanics. I run bedslinger at work for weeks or even month on end without remapping and get perfect first layers. Needing remap means mechanical issues(or bad probe) which are better be fixed before employing software crutches.

[mpheyse]

Its just adding one variable that already exists in the command, and the Suspend functionality already exists. So its not much of an edit, and it effects noting if not used.

@Nuck-TH
Your 'Sound too complicated' is a bit subjective. I listed all the end cases for the variable in "Additional context", you can just limit yourself to the "Describe the feature you want" section if you need a simpler description.

I'm happy that stored ERPOM data works for you, its not what were doing. Our cheap (sub$1000) printer's beds are not flat, and change significantly with temp, and plate removal, and plate types.

Bambu's 7minute startup every time, make those printers much better print quality, and were finding the same with our older frame printers, running compiled Marlin. And a very much dislike waiting for those startups too.

And 8min is a long time to wait so the 1min30 after that for the Hotend is VERY annoying to sit and wait for a first layer check.

I'm not fine with the wait, I'm trying to reduce it..

.. not needed with good Z endstops/probe and sound mechanics. I run bedslinger ....

Throwing more hardware at a software fix is not a perfect solution for every one, and every budget.

[thinkyhead]

It's a fine approach if it can be made to fit the ubl_G29.cpp code. I say go for it and submit a PR. It fits within our general ethos of keeping our procedures simpler and allowing choices like this to be made in the slicer. The overloading of G29 with UBL is already pretty obscene, so we might try to make that nicer. But sure, a way to "probe X points" and then "probe X more" and "probe the rest" seems like something that might be good for these progressive heating scenarios, if it must be done within the bounds of G29 according to the limitations of our current design.