BLTouch working

W3DRK

Ok thanks for mentioning that! Certainly saves me some troubleshooting…

There appears to be a bug along the lines you describe when using heater 3 as a servo. It's on my list to fix in 1.17. The other expansion heater channels don't have the problem.

dc42

This bug is fixed in the 1.17dev4 build. It turned out to be an undocumented chip-level bug in the PWM subsystem and it took me hours to find a workaround.

W3DRK

David, I can't thank you enough for all the hard work and dedication you contribute to this firmware! I'll install your 1.17 dev build this weekend and let you know how it works out.

Alex9779

I was curious so I ordered one too.
I set all up so far for testing and but stumbled over something.
The BLTouch is 5V powered from the servo input so its output signal is also 5V.
I know, and it is described, the resistor is also provided, that I can use the 240ohms resistor between the output and ground to reduce the voltage.
But I am a proud beta tester of the Duex2 and it provides endstop ports where I can select the operating voltage…
All I need now would be a remapping possibility that a probe of type 4 (M558 P4) would not use E0 endstop but E2 or E3.
@dc42 would that be possible or is this outa reach? I just wanna be safe and a resistor crimped into the plug or soldered in somehow might break and then I have a problem. With the Duex now allowing 5V endstops I could omit the resistor and just use one of those native ports.

dc42

That could be done, but it is not likely to happen soon because my priority is to finish the grid bed compensation code.

I think it is very unlikely that that 5V applied to an endstop input on the Duet WiFi would damage the microcontroller, because the endstop input includes a series resistor. The Z probe input is even better protected. So I suggest you use the resistor, connect it to the Z probe input, and select probe type 4.

Alex9779

Hmmm but the manual states that type 4 uses E0, so how can I connect it to Z probe input?
Or are they the same?

Edit: reading between the lines of the documentation I assume yes… But I found no definite statement....

dc42

Sorry, I meant type 5.

W3DRK

David, I forgot to update that 1.17 dev4 does indeed fix the delay with heater 3 as a servo on a wired Duet. Everything is working absolutely perfectly and I'm extremely pleased with how well the BLTouch works. Thanks!

W3DRK

@Alex9779:

I just wanna be safe and a resistor crimped into the plug or soldered in somehow might break and then I have a problem. With the Duex now allowing 5V endstops I could omit the resistor and just use one of those native ports.

For what it's worth I soldered and crimped the resistor in my end-stop connector just to make absolutely sure it's well connected.

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