FW 3.0.6RC - Auto Home == Z-calibrate?  

Re: FW 3.0.6RC - Auto Home == Z-calibrate?

Sandro

Yes, this is something that was introduced in 3.0.4 I think.

To me, it is just silly; I can see no reason for doing it. But then the way PR have misused the standard Marlin GCodes, this does not surprise me.

Peter

Re: FW 3.0.6RC - Auto Home == Z-calibrate?

Hmm, I'm pretty sure 3.0.5RC version of auto-home only did the homing (at least from the menu).

I never used 3.0.4RC, so I can't say if that one did or didn't.

I'm against the abuse of the GCodes, but I would accept them as defaults, if there was a setting that allowed us to switch to more traditional behavior. Seems like we should have an "expert" mode, where things like the z-axis power switched with the other steppers.

Re: FW 3.0.6RC - Auto Home == Z-calibrate?

No (for me anyway) 3.0.5 RC did the calibration with auto-home and I think 3.0.4 beta may also have done that. I set up with 3.0.3 (I think; it's been a while so I can't remember) and I used auto-home many times to get the nozzle height correct.

Peter

Re: FW 3.0.6RC - Auto Home == Z-calibrate?

Kind of a mess.

I've been playing with a head cleaning mechanism that I can run prior to the Z calibration.

If I construct such a thing, I need the home to do only that -- just home, not the full z-calibration.

Re: FW 3.0.6RC - Auto Home == Z-calibrate?

G28 W

That apparently homes all exes.

Peter

Re: FW 3.0.6RC - Auto Home == Z-calibrate?

Kind of a mess.

I've been playing with a head cleaning mechanism that I can run prior to the Z calibration.

If I construct such a thing, I need the home to do only that -- just home, not the full z-calibration.

Speaking of which, as a newbie it makes no sense to me that the printer first heats the nozzle (generally oozing some afterwards) and THEN performs the calibration, then dragging the oozed filament all over the print bed. Wouldn't it work better to calibrate first, then heat?

(Of course there may be some reason for this way that I'm not aware of, but it seems odd to me.)

Re: FW 3.0.6RC - Auto Home == Z-calibrate?

Objects expand when heating up. The degree of expansion varies with the temperature, which is why it makes sense to pre-heat the bed and the filament for a pre-print Z calibration. That way your calibration is based on numbers gathered from when all parts are at their operating temperature for the print. Calibrating with everything at room temperature would yield different results.

If the oozing really poses a problem, I have found pre-heating and allowing 1-2 minutes before starting a print allows you to remove any oozed material from the heated bed, allowing for a clean pre-print calibration.

Re: FW 3.0.6RC - Auto Home == Z-calibrate?

Wouldn't it work better to calibrate first, then heat?
No. The calibration would be lost because of thermal expansion. Another reason is that any debris on the nozzle pushes the bed down (while cold) and ruins the calibration.
I personally don't mind about a bit of filament oozed on bed during calibration. If it happens, I clear it from bed when extruder is at 9th point. 2-3 quick moves with spatula do the job.

Re: FW 3.0.6RC - Auto Home == Z-calibrate?

Objects expand when heating up. The degree of expansion varies with the temperature, which is why it makes sense to pre-heat the bed and the filament for a pre-print Z calibration. That way your calibration is based on numbers gathered from when all parts are at their operating temperature for the print. Calibrating with everything at room temperature would yield different results.

If the oozing really poses a problem, I have found pre-heating and allowing 1-2 minutes before starting a print allows you to remove any oozed material from the heated bed, allowing for a clean pre-print calibration.

There are at least... I don't know, 2 or 3 things wrong here.

It may make sense to pre-heat the bed as that is a pretty large area to deal with, plus pre-heating it doesn't really affirmatively cause problems.

It makes little sense to preheat the hotend to *FULL TEMP* to probe. If you're *not* using the hotend itself as the probe (i.e. an on-carriage FSR setup), then the hotend does doesn't matter.

Heating it up to only 170 prevents ooze while still warming things up for both the probe and the user. If you were really worried about expansion throwing off your measurements, I'm sure this would take the edge off that. You don't have to run around beating everything into submission with large hammers -- a gentle, deliberate, precise preheat will do fine.

The subtle reason for heating it up at all is really to soften up any ooze that might already be on there so that the hotend, which is already too close to the bed because they chose a probe with too short a focus distance, will squish it down instead of ramming into the bed as a hard object.

The other caveat here is the second design mistake, which is putting the probe mount directly downwind of the hotend fan. That's like urinating in a river upstream of where you're drinking. If you were worried about probe errors due to thermal effects, WHY PUT THE PLASTIC PROBE MOUNT DOWNWIND OF THE HEAT SOURCE?

That one thing, right there, I suspect is responsible for the majority of probe drift, and why the PR guys are slathering their probes in threadlock, not realizing the real source of their drift.