Duet Wifi and BLTouch

[fcwilt]

The most important function of the Z probe is to set the X=0 datum.

You generally want to do this at the center of the bed and you always use the same point.

This needs to be done...

• after you level the bed with G32
• before you create a height map with G29
• before you load a existing height map with G29 S1

You can do it as the last step of homing Z but that is not essential.

[fcwilt]

Hi,

If you are not using firmware v3.1.1 or v3.2 I strongly suggest you do so.

It makes leveling the bed with multiple steppers very simple.

Frederick

[ozi]

So it wont work like i tried ?

I think my bed is a little bit heavy so its to easy that one of the leadscrews will turn a little bit when the printer is off. And this will make the heightmap unusable... I dont want to mesh bed levelin every day ..

what does the new firmware do different with bltouch? I will try tomorrow.

[fcwilt]

@ozi said in Duet Wifi and BLTouch:

So it wont work like i tried ?

I think my bed is a little bit heavy so its to easy that one of the leadscrews will turn a little bit when the printer is off. And this will make the heightmap unusable... I dont want to mesh bed levelin every day ..

what does the new firmware do different with bltouch? I will try tomorrow.

Hi,

Let's agree on some terms first.

Mesh compensation is the firmware feature that allows the firmware to adjust the Z co-ordinate during printing to compensate for bed irregularities.

While it can compensate for a bed that is not level that is not it's main focus.

Mesh compensation requires creating/loading a height map. The base command is G29.

So don't think of it as leveling the bed - that is a different firmware feature.

The firmware offers two ways to level the bed...

• (the) Manual Bed Leveling Assistant (MBLA)
• Automatic Bed Leveling (ABL)

They are similar but MBLA relies on turning bed leveling thumb screws by hand whereas ABL relies on adjusting multiple Z steppers to level the bed.

The base command is G32.

It looks like you have two independent Z steppers so you can use ABL.

One of the many advantages of firmware v3 is it simplifies using ABL.

I don't know of any significant differences in it's handling of a BLTouch.

I have a printer with three Z steppers and I use ABL - it works great.

I also use mesh compensation but I have found that I can use the same height map as long as I use ABL before creating the height map and before loading the height map to print.

So consider upgrading to v3 firmware and let me know.

Frederick

[Phaedrux]

It's much easier with RRF3.

https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors#Section_In_RepRapFirmware_Num_3

After leveling the bed with that technique make sure you set Z0 with the probe by using G30 at the center of the bed before you run G29 or G29 S1 and start a print. @fcwilt has you covered.

[ozi]

Thank you all !

I am a little bit confused and feel like an idiot ...

To explain why I am trying this with zmax is:
I used and tryed the ABL with the bltouch like explained in this tutorial with RFF2:
https://duet3d.dozuki.com/Wiki/Bed_levelling_using_multiple_independent_Z_motors#Section_In_RepRapFirmware_Num_3

I run first G32 and then G29 to create a height map. I then changed my start gcode from G28
G29 S1
to
G32
G29 S1

I thought that is ok because G32 runs bed.g and the first line of bed.g is g28. But now I see (thanks fcwilt) I had to set X=0 AFTER G32 - maybe this was my issue why I had the feeling the G32 changes my heightmap.

So today, I will upgrade to RFF3 an try it again but im confused about the tutorial now.

For RFF2 in bed.g it says :"M401 ; deploy Z probe (omit if using bltouch)" so I uncommented it and the bltouch is probing the bed to the center, then left at the near of leadscrew and right the same.

For RFF3 the tutorial is "speaking" again from "endstops" so now I am confused. (Sorry for my english :(.. ).

So is it right, I can use 2 endstop in Z MIN ! to make the ABL and the BLtoch for G28 and G29 to home the center and create a heightmap? Sorry If I am annoying..

[ozi]

So I have now updated to RFF3. I unplugged for the first installation the 2 z optical endstops and in the configuration tool I choosed Z-Probe as Z endstop at low and and configured the bltouch for the probe.

In config.g I made changes in M584 to get the second z motor working like:
M584 X0 Y1 Z2:4 E3

So now when I do homeall it is using the bltouch as my "z endstop" and both z motors are working.

Now as fcwilt described, its only a z probe but not ABL? I think I have now understanded it. Z Probe is not the same like Z home.

So homez calls the motor to home using endstop and G29 calls a probe definied with M558 P9 (for bltouch). I think i have it now and I dont need zmax and can use zmin.

I will try now and will report my progress

[ozi]

I give up..

Tryed everything what i can but it wont work use 2 endsop switches and the bltouch for probing.

I removed the jumpers and put the second z motor back from e1 to z2 again and will only use bltouch as probe and endstop.. maybe one day I will find someone who has time to explain and test it with me.

thank you all

[fcwilt]

@ozi said in Duet Wifi and BLTouch:

I give up..

Tryed everything what i can but it wont work use 2 endsop switches and the bltouch for probing.

I removed the jumpers and put the second z motor back from e1 to z2 again and will only use bltouch as probe and endstop.. maybe one day I will find someone who has time to explain and test it with me.

thank you all

When using end stop switches with ABL the z probe is only used AFTER to reset the Z=0 datum.

Recall that I have 3 Z steppers, each with their own end stop switch, for my bed.

Here is most of my homez.g file:

G91                  ; relative moves
G1 Z-399 F1200 H1    ; move up until endstop switch is activated
G1 Z20   F600        ; move down a bit
G1 Z-25  F300  H1    ; move up until endstop switch is activated
G92 Z10.200          ; set Z as needed to yield accurate Z = 1
G90	             ; absolute moves
G1 Z10 F1200         ; move nozzle to known position
G32                  ; invoke bed.g to level bed - pass 1
G32                  ; invoke bed.g to level bed - pass 2

Note that each Z stepper keeps moving until it's end stop switch is activated. Once all are activated the next step in the homing file takes place.

Frederick

[ozi]

I have tryed like your homez.g file and in config with M584 Z2:4, but had the following issue:
G91
G1 Z-305 F600 H1 -> Only the z motor connected on Z is moving the other one is not moving

Then I trigger the switch for Z and now BOTH motors going 20mm down (G1 Z20 F600) and then with G1 Z-25 F300 H1 the same only one motor is going up again.

And the same when I trigger the switch a second time BOTH motors are going down zo G90 Z10

I had M584 Z2:4 in config.g
I had M574 Z1 S1 P"zstop+e1stop"

but when z moving to Endstop (with H1) only one stepper is moving, when moving without H1 both are moving..

I dont now.. i give up

[fcwilt]

@ozi said in Duet Wifi and BLTouch:

G1 Z-305 F600 H1 -> Only the z motor connected on Z is moving the other one is not moving

That tells me that the end stop switch for the other stepper is already activated. Remember that with H1 the move stops when the end stop switch activates or is already activated.

Then I trigger the switch for Z and now BOTH motors going 20mm down

Triggering the switch completed the first G1 H1 move and then the G1 Z20 command was executed.

then with G1 Z-25 F300 H1 the same only one motor is going up again.

Again because the end stop switch for the other stepper is already activated.

And the same when I trigger the switch a second time BOTH motors are going down zo G90 Z10

Triggering the switch completed the second G1 H1 move and then the G1 Z20 command was executed.

---

Everything you see is consistent with the other end stop switch being activated at the start.

So find out why the other end stop switch is not working and your good to go.

Frederick

[ozi]

@fcwilt When the other switch was triggered then the red led from the optical switch should show it but it wasnt triggered.. maybe wiring issue..

I found another topic here:
https://forum.duet3d.com/topic/9684/bl-touch-and-two-endstop-switches/2

he wanted to make the same like I but no response from him if it worked...

there was a suggestion to use bed.g for leveling the bed and bltouch to probe..

I will try later more..

[fcwilt]

@ozi

Hi.

Homing the bed with multiple Z steppers/end stop sensors is a different issue from leveling the bed.

You can do both.

I think I mentioned that my printer has 3 Z steppers each with it's own end stop sensor.

If your end stop sensors are correctly position you can get your bed decently level.

To "fine tune" the leveling you use your Z probe and Automatic Bed Leveling (ABL - base command G32)

Can we get your homing working first?

Frederick

[ozi]

@fcwilt Oh my god.. I am the biggest idiot the last days here.. my god.. i feel really bad now

It was my false wiring.. i plugged the endstops to E0 and Z insted auf E1 and Z.. i am so sorry that i wasted your time. If you ever come to austria/vienna i will spend for some beer..

So now I can use homez.g and homeall.g to home both z steppers. And G29 to create a heightmap with the bltouch. I made a makro with G30 in the center of the bed to probe the center if i had do measure the z offset for the bltouch.. Soo now i am heating up my bed, will use homez.g get the z=0, then I will level manuelly with the screews and create a heightmap with bltouch to get it perfect

[fcwilt]

@ozi said in Duet Wifi and BLTouch:

austria/vienna i will spend for some beer..

That is weird that you should mention that.

My wife and I were chatting just day or two ago about places we would like to visit while we were still above ground.

As part of our research I used Google Earth to "visit" Vienna.

Frederick

[ozi]

@fcwilt vienna has a big history and a lot of sightseeing so just pm me if you ever come over