Homing Extra Axis on XYZ+C printer - S1 Issue


By Algadz 21 April 2017 10:22

Member · 7 comments

Hi everyone,

First of all, thanks to the Duet team for this wonderfull board full of possibilities 😁

I'm working on a 4 Axis particular 3d printer ( XYZCE) with a 0.8.5 DUET ( firmware 1.18.1) and I would like to home the XYZ and C axis.

I'm doing some test with Pronterface and so far I have :

Remapped my axis with the following command :
M584 X0 Y1 Z2 U3 E4

Set up the endstop with :
M574 X1 Y1 Z1 U1 E0 S0

I have checked that my endstop are working fine with the M119 and the board detect all the endstop on and off correctly and I can see them being activated on the board LEDS.

Everything works fine on the XYZ when I simulate this type of homing macro :

G1 X-100 S1
G92 X0
G1 X5

However when I am doing this same homing routine on my U axis ( which is my C rotary axis ).
I am able to make a move and to stop when the endstop is activated with G1 U100 S1

But after this command I am unable to re-use any G1 command without adding S1 or S2 at the end (with the endstop activated or deactivated)
I mean :
If I try G1 U10 nothing moves ( either in absolute or in relative mode)
If I try G1 U10 S1 the axes moves as expected.

If I restart the board, I am able to use G1 U10 without S1 at the end. This problem appears right after using S1 on the U axis for the first time.

Also I don't have this Issue on the XYZ axis.

Did I remapped correctly my axis ? Did I miss Something ?

Thank you for your help 😁
And again, thank you for your work.

Last edited by Algadz (21 April 2017 11:00)


By dc42 21 April 2017 15:56

Administrator · 2,672 comments

You need to declare the positive and negative limits of the U axis in your M208 S0 and M208 S1 commands respectively. The negative limit will also be the assumed position of the U axis after that G1 U100 S1 command because you have declared the limit switch to be at the low end of the U axis.

Duet WiFi hardware designer and firmware engineer


By Algadz 25 April 2017 16:30

Member · 7 comments

Oh right, 
the U axis (wich was initially E0), had upper and lower software limit of 0 (checked with "M208" command).
That was probably causing the trouble.

Ok I didn't know that the "G1 U100 S1" command (once the endstop is activated) is acting just like the G92 command. Good to know !

Thank you for your answer 😁