How to Home Z on Dbot CoreXY??

flawi

I just assembled a DBot with a Duet Wifi and am in process of calibrating/tuning now.

I finally got the homing working on all axis, relevant configuration files here: https://drive.google.com/open?id=0B4QI9opJS9SbSldRZjQ5NUd0U2c

I hope those are of some help.

titanhusker

I will check those files out as soon as I am home tonight. Is your printer configured with 1 or 2 Z axis motors? Got any pics?

flawi

Regarding your Z endstop, it seems that the microswitch has been bent out of position by the endstop screw on the bed platform.
The original mounting bracket is correct, but the switch itself is supposed to be flush with the PCB, see: https://drive.google.com/open?id=0B4QI9opJS9SbTUp3VE0tWHVSY1k

The first thing I'd do if I were you is to verify that the platform moves in the correct direction, pressing Z +0.1mm in the UI is supposed to move the build plate DOWN. If it doesn't, you need to change the Z motor direction in your config.g then try again.

If that works, I would suggest you take a copy of my homez.g and verify manually that it works as it should.
What I mean by manually is that you

move the build plate down from the UI to something like 100mm (do this in small steps in case your steps/mm is incorrect, simply clicking "Z +100mm" might translate to some ridiculous value in those cases)
click "Home Z" in the web ui
verify that the build plate starts moving towards the hotend and
use your finger to push the Z endstop to verify that the build plate stops. If it doesn't, hit the emergency stop in the UI before the bed crashes into the head/endstop.

E: I'm using the default 2 Z-motor setup, but it's a pain in the butt. Be glad you only have one, my Z axis gets all wonky as soon as I turn off the Z motors since one side will start sagging while the other will stay put. Probably the first upgrade I'll do is either a 1 Z-screw or 3 Z-screw modification. I kinda like the linear rod setup you have on yours, will consider something similar.

titanhusker

Hey flaw I,
I meant to also ask did you configure yours with a z probe or end stop? And what orientation / location is your Z end stop if using one? That is why I asked if you had any pics.

flawi

Yeah, I have a Z endstop. There's a link to a picture of it in the previous post. The pic can be found in the same folder as as the config files as well.

titanhusker

Ah, did see you responded so quickly. Yes that is how mine looked, therefore I will put it back in that same position like you have. The screw did bend the end stop, but it looked like it wasn't hitting before the issues. I will check it again as well.

When I hit move Z in plus it does move down towards the bottom and - moves it towards the hot end. Is that correct?

titanhusker

When I get home this evening I will give your config files a try and post feedback on them. I really appreciate you helping out.

flawi

@titanhusker:

Ah, did see you responded so quickly. Yes that is how mine looked, therefore I will put it back in that same position like you have. The screw did bend the end stop, but it looked like it wasn't hitting before the issues. I will check it again as well.

When I hit move Z in plus it does move down towards the bottom and - moves it towards the hot end. Is that correct?

Yeah, that seems correct. I was only saying to verify that as that was my first problem with getting Z homing to work, I had it the wrong way around and somehow associated "+" with "up", without realizing that it's inverted since it's the bed that moves and not the hotend like on my Prusa i3.

E: Another thing worth noting is that the end stops will not work when you're manually controlling the printer.
So if you're physically at Z50, and tell the printer to do a relative move of Z-100, it will crash right through the endstop. Just something to keep in mind, I learned this the hard way.

titanhusker

Hey flawi,

I have had a chance to implement your file structure and I have to say a BIG thank you. Worked perfect, everything homes in exactly as it should. I looked through the config files you generated and I like some of the features, they were better than the originals. I did have to obviously modify the code for my specific setup, such as my hot end. Speaking of which one piece of code is missing or not doing what I need it to. I usually can enter a temp amount in the main screen and it will turn the hot end on and let me know it is active. I can enter the amount of temp, but it doesn't turn it on. There is something I am missing? Any ideas? Here is the coding for my hot end.

; Heaters
;*** You can use S and B parameters to define the parameters of the thermistors you are using

M305 P0 T100000 B4388 R4700 H0 L0 ; Put your own H and/or L values here to set the bed thermistor ADC correction
M305 P1 T100000 B3974 R4700 H0 L0 ; Put your own H and/or L values here to set the first nozzle thermistor ADC correction

;M301 H1 P10 I0.10 D100 T0.50 S1.0 ;PID settings for extruder 0 (no need for M301 if using M307)
;M301 H2 P10 I0.10 D100 T0.50 S1.0 ;PID settings for extruder 1

M570 S120 ;Increase to allow extra heating time if needed

M307 H0 A81.5 C538.5 D7.0 B0 ;Autotune result for bed
M307 H1 A561.2 C268.8 D6.9 B0 ;Autotuen result for first nozzle

titanhusker

flawi,

Any chance you made a config-override.g file? I would love to take a look at that as well if you did. Thanks again for all of your help!

flawi

Glad to hear you got it working!

I added my config-override.g to the same folder on Drive. It only includes the results of the PID autotuning so nothing very interesting.
I see your other problem was already answered in the other thread, you just need to set some tool as active. I have it in my Slic3r start code, but I guess it could just as well be in the end of config.g.