BLTouch working

deckingman

Just curious as to how accurate this BL touch thing is for homing. I currently use DC42s excellent probe which works fine but the slight issue I have is that I have 3 pieces of glass with different surface coatings that I swap between. So if I go from say, plain glass with 3DLAC to glass with blue tape, I have to edit my config.g to change the Z offset for that particular surface. It occurs to me that the BL touch might negate the need to do that. Is that reasonably assumption?

BTW, I've managed to build my machine such that the bed is both flat and level and stays that way, so I have no need to compensate for level or flatness (although it is nice to use the probe to check from time to time). It's just Z homing with different surface materials that I'm interested in.

T3P3Tony

Ian

How about a black sticker at the corner of each bed plate - be out of the way for nearly every print and should give the same result?

(sorry to hijack the bl touch thread!)

deckingman

@T3P3Tony:

Ian

How about a black sticker at the corner of each bed plate - be out of the way for nearly every print and should give the same result?

(sorry to hijack the bl touch thread!)

Tony - that's a damned good idea - so simple! My initial reaction was that it wouldn't work with blue tape due to the thickness of the tape itself, but as long as the black sticker is on top of the tape (or any other material) then of course it will work. Brilliant! Thanks

W3DRK

@deckingman:

Just curious as to how accurate this BL touch thing is for homing.

Antclabs claims a standard deviation of at least 0.01mm–apparently dependent on the probing speed due to the way hall-effect sensors work. I haven't had time to do more than about a dozen prints on this machine since fitting it with the BLTouch, but so far it's been working great and I haven't needed to adjust the Z offset since the initial setup. Perfect first layers every time.

StephenRC

@deckingman:

I currently use DC42s excellent probe which works fine but the slight issue I have is that I have 3 pieces of glass with different surface coatings that I swap between. So if I go from say, plain glass with 3DLAC to glass with blue tape, I have to edit my config.g to change the Z offset for that particular surface.

Use a macro to set the z offset. I have one for pla and another for petg. The two different filaments need a different z0 setting to get it to stick properly.

Treito

Did you directly connect the Servo to Pin21? Does this PIN provide 5 volts or would I need some sort of diode?

Jdn-za

Just ordered myself a bltouch and will be adding it to my duet 0.8.5, thanks for documenting the install mate

Sniffle

W3DRK, just curious, does each successful probe actually reflect in the web interface for you? I have mine setup nd everything is working but to test before i have a bed crash i deployed the probe and manually actuated the pin maybe 1 in 10 seems to actually register in the interface though.

just to make sure i slowed my manual testing speed way down but still had several swipes that werent displayed on the interface.

on my meter my resistor came out to 241ohms so it "should" signal ok…

Jdn-za

W3DRK, So I have wired up my bltouch int he way that have described but cant seem to get my duet to deploy or retract using macros or gcode.

I have the following defined in my config.g

; BLTouch
M307 H3 A-1 C-1 D-1
M558 P4 X0 Y0 Z1 H3 F200 T5000    	
G31 P200 X-4 Y40 Z2

I am running the latest stable dc42 fork of the Duet 0.8.5 firmware

Firmware Version:	1.17a (2017-01-02)
Web Interface Version:	1.14-RC1

Any ideas what to look at?

tomwang256

Are you on duet 0.8.5 or duet wifi? I have BLTouch wired up with my wifi working well.
it's mostly the same instruction that W3DRK but the expansion header is not the same on the wifi so you would have to use pin 8 for Heater 3 pwm output instead.
see documentation here : https://duet3d.com/wiki/Duet_WiFi_wiring_diagrams

Jdn-za

@tomwang256:

Are you on duet 0.8.5 or duet wifi? I have BLTouch wired up with my wifi working well.
it's mostly the same instruction that W3DRK but the expansion header is not the same on the wifi so you would have to use pin 8 for Heater 3 pwm output instead.
see documentation here : https://duet3d.com/wiki/Duet_WiFi_wiring_diagrams

I am using the Duet 0.8.5

Jdn-za

Ha! seems my signal wire was busted

My deploy marco works though the retract doesn't

deploy

M280 P3 S10 I1

retract

M280 P3 S90 I1

If I home Z it deploys, lowers and reads the height then deploys and flashes

Jdn-za

Seems I just had the wrong value in my retract macro… awkward

InSanity

First post to the forum.

I have the BLtouch working with my Duet Wifi, well somewhat. It homes fine and has consistent heights. The problem I'm having is with the new Grid compensation. I fire off the deployprobe.g in the bed.g followed by G29 and the machine goes to the first probe point , probes and then moves to the next. The 2nd point gets the following error :

G32
Error: Z probe already triggered before probing move started

This of course is because the probe doesn't get deployed again once triggered by the first probe point.

Hopefully someone can tell me where my error in logic is. It seams to me like the deploy is just not being called between points, possible flag to allow that ?

Thanks,

Jeff

Sniffle

M558 P4 X0 Y0 Z1 H4 F400 T500

http://reprap.org/wiki/G-code#M558:_Set_Z_probe_type

On M558 you need to set an H parameter so that the bed(or X axis) will move away from the probe(giving the probe room to allow the pin to fall back into the deployed position) so that it will not error(blinking probe will cause the endstop to be considered triggered always) you may also need to increase your F parameter to increase the speed of movement on the Z axis so that also doesnt cause the probe to error.

The probe should not be retracted between probing. It should trigger and drop back down each time. If you deploy the probe manually using M280 with plenty of clearance from the bed and use your finger to push the pin up it should pull away from your finger flash red and then drop back down when operating correctly. the retract probe command should only be done after finishing the probing.

InSanity

I must be doing something wrong when I deploy the probe. No matter what the pin always gets sucked back up instantly. The probe isn't going into error mode at all, it just never stays deployed after being triggered.

This is what I'm doing with the deployprobe.g file. (M401)

M280 P3 S10 I1 ;Deploy probe
G4 P75 ;Wait 75ms
M280 P3 S60 I1 ;Test mode
G4 P125 ;Wait 75ms

This triggers as expected however it always sucks the probe up the instant it's triggered and doesn't try to drop it. If I don't include the "test mode" it just slams into the bed and then eventually triggers and goes into alarm. The bed doesn't even try to retreat until well into a crash. Even on a home without the test mode it just crashes into the bed.

I would have expected the trigger to occur the moment the pin reaches a certain level like it does while in the Test Mode.

BTW I'm running a Flashforge Creator Pro with the Duet WiFi , New Steppers, new carriage and the E3D Legends Pack. All new wiring with a 24 pin Molex MicroFit 3.0 on the back so I can swap out carriages. Prints like a champ with an inductive sensor, the IR sensor I just didn't have much consistency with.

Jeff

InSanity

Playing around over here. I changed the deploy to

M280 P3 S160 I1 ;Clear any alarm
G4 P450 ;Wait 75ms
M280 P3 S10 I1 ;Deploy probe
G4 P75 ;Wait 75ms

I went from H 3 to H 5 and F 120 to 320, now it just crashes faster and never tried to retreat. The probe still goes into alarm mode. It's as if the trigger is delayed, I don't see this problem if I put the probe in Test Mode. I'm using the Z-Probe into for the trigger, I can't imagine that would matter. I can toss a scope on the pin to see what it's doing I guess.

Jeff

InSanity

Ok I'm starting to think it is a problem with the Z-Probe not responding fast enough for the 50ms pulse. I'm going to try the Z Endstop. The Z-Probe input does have a 10k resistor and a small cap, I can't imagine that would take too long to reach a good logic level. We shall see.

Jeff

InSanity

I meant to say E0 in my last random thought. In any event I'm seeing the exact same behavior. The bed crashes, the trigger is not seen unless I put the probe in test mode. I'm running 1.17a firmware.

Jeff

Sniffle

according to the bltouch people, to work with 3.3v logic electronics you only need a 240ohm resistor in line with the 2-wire endstop. that could be where your not gettign a response. I will say that the web browser doesnt always refresh the probe trigger value fast enough for the trigger to show and I also have my z-probe trigger value set obscenely low to something like 25 since the pulse is so short.

G31 X-30 Y35 Z1.1 P25

as to the deploy this is all my macro is(on H3) M280 P3 S10 I1

I clear alarms separately as i feel that is just a safety check.