Height Map - Substantial z-offset after setting z-offset

TimsWorkshop

@fcwilt No, do I just exclude G29 S1 from the start of the Gcode?

I just test printed a 5 square bed level print and noticed that on the back left side, the extruder motor moves back/fourth in what looks like the same distance, essentially not extruding anything

fcwilt

@infidelprops said in Height Map - Substantial z-offset after setting z-offset:

@fcwilt No, do I just exclude G29 S1 from the start of the Gcode?

Yes - that will do it.

Frederick

TimsWorkshop

@fcwilt Just removed it and re-printed.. same problem... Extruder stops extruding in the exact same spots. I recorded a video, just uploading it now.

I'm not on 3.4, I'm on 3.3 - is this bug a 3.4 bug, but even if not, this is now a new problem....
Maybe I should open a new thread for this one?

TimsWorkshop

@fcwilt Here's the link: https://youtu.be/SWRAStyB8W8

fcwilt

@infidelprops said in Height Map - Substantial z-offset after setting z-offset:

@fcwilt Here's the link: https://youtu.be/SWRAStyB8W8

Is it failing to extrude because the nozzle is too close to the bed surface?

Frederick

TimsWorkshop

@fcwilt That was my first thought, but if that was the case, we'd hear it clicking and not seeing the extruder gear hoping back and fourth, yeah?

fcwilt

@infidelprops said in Height Map - Substantial z-offset after setting z-offset:

@fcwilt That was my first thought, but if that was the case, we'd hear it clicking and not seeing the extruder gear hoping back and fourth, yeah?

Well when the nozzle on my primary printer gets too close nothing comes out but I've never noticed any kind of clicking.

I use Zesty Nimbles v1.x and it may be they just "grind" the filament.

Frederick

TimsWorkshop

@fcwilt I'm going to open a new thread.. just experience a very strange issue!

fcwilt

@infidelprops said in Height Map - Substantial z-offset after setting z-offset:

@fcwilt I'm going to open a new thread.. just experience a very strange issue!

Sound sensible.

What time is it where you are?

I'm supposed to still be in bed here.

Frederick

TimsWorkshop

@fcwilt I was wondering when you were going to knock off! I'm in Australia, it's only 7:15pm here.

fcwilt

@infidelprops said in Height Map - Substantial z-offset after setting z-offset:

@fcwilt I was wondering when you were going to knock off! I'm in Australia, it's only 7:15pm here.

It's 5.15am - I got up to get a drink and saw your posts - it seemed only right to respond.

Frederick

TimsWorkshop

@fcwilt said in Height Map - Substantial z-offset after setting z-offset:

It's 5.15am - I got up to get a drink and saw your posts - it seemed only right to respond.

Frederick

Maaate.... Way to kind and I really appreciate the help! I hope you got some rest and coffee!

TimsWorkshop

@fcwilt hey mate, so what do you reckon is going on here? I did a print last night and this morning started a new one, but noticed I had to make some large baby step corrections.... so I stopped and re-ran a G29 and a huge difference in my mesh...

Mesh done two nights ago:

Mesh done just 5 minutes ago:

I can probably run a G32 and will have to adjust the springs... but what a shocking difference in just two days.

fcwilt

@infidelprops

You are still doing the single G30 at bed center to set the Z=0 Datum before doing G29 to create the height map?

Frederick

TimsWorkshop

@fcwilt said in Height Map - Substantial z-offset after setting z-offset:

@infidelprops

You are still doing the single G30 at bed center to set the Z=0 Datum before doing G29 to create the height map?

Frederick

Yeah it is

fcwilt

@infidelprops said in Height Map - Substantial z-offset after setting z-offset:

@fcwilt said in Height Map - Substantial z-offset after setting z-offset:

@infidelprops

You are still doing the single G30 at bed center to set the Z=0 Datum before doing G29 to create the height map?

Frederick

Yeah it is

Well I don't know what is happening.

In theory if the height map is created after setting the Z=0 Datum at bed center, then a few points of the height map which are near bed center, ought to have an Z offset close to zero, as indicated by the green color in the upper height map image.

Are there any commands between the G30 and the G29 that might be causing the problem?

Frederick

TimsWorkshop

@fcwilt A few, but it's just doing a double probe before G29 starts:

M558 F900              ; Home EZABL Fast 15mm/s
G30                    ; home Z by probing the bed
M558 F450              ; Home EZABL Slow 7.5mm/s
G30                    ; home Z by probing the bed

fcwilt

@infidelprops said in Height Map - Substantial z-offset after setting z-offset:

@fcwilt A few, but it's just doing a double probe before G29 starts:

M558 F900              ; Home EZABL Fast 15mm/s
G30                    ; home Z by probing the bed
M558 F450              ; Home EZABL Slow 7.5mm/s
G30                    ; home Z by probing the bed

If you are in fact using a EZABL probe you may need to slow down the probing speed.

Unless they have some tech trick up their sleeve (which they may) their probe is described as a capacitive device with 100 Hz switching frequency.

I've tested a number of different inductive and capacitive probes and found the capacitive probes needed a much slower probing speed than the better inductive ones. Generally the higher the switching frequency the shorter the response time. I have some inductive probes with a 3000 Hz switching frequency.

So, just as a test, probe just once at F100, rather than twice at 900/450, and see if that makes any difference.

Frederick

TimsWorkshop

@fcwilt Thanks mate - I'll give it a go

TimsWorkshop

@fcwilt so I did a G32 and had to adjust the knobs again, and then ran a G29 with one probe and F100... it took a while, but mesh looks much better. We'll see how it looks tomorrow after a 20hr print.