Z probe hitting the Z rod while X homing

Sardi

Owner of an RepRap Ormerod 2 here. As Im not using my printer often, Ive been manually homing my X axis and I was ok with that.
Now that I have some more free time, Id like to make use of my Z modulated probe that I have mounted so to have it automatically homed by the press of the button.

BUT..

The X mount, and by that I mean the fan, keeps hitting the Z rod because the Z probe does not stop when its triggered by the bar with the piece of white paper.

Now, everything seems to be working:

z probe value aways from the bar is 10, over the white paper is 500+
I have both M574 X1 S2 (needed by the firmware) and M574 Y2 Z1 S1 in my config.g
M558 P2 is set for modulated probe in the config.g
firmware and web control is RepRapFirmware 1.20 by @dc42
instructions for installing the firmware were followed
the homex.g is proprely set

G91
G1 Z2 F200
G90
M558 P1
G1 X-240 F1500 S0
G92 X0
G1 X3 F200
G1 X-30 S0
G92 X0
G1 X15 F500 ; adjust the X value to put the nozzle on the edge of the bed
G92 X0
M558 P2
G91
G1 Z-2 F200
G90

Everything is as it should be, the X head moves as it should, the Z probe is working, but its as if the probe does detect the white paper but it does not send the information back for the movement to stop and go to the next gcode value.

Any ideas would be highly appreciated as im out of options.

droftarts

@Sardi In homex.g change the G1 X ... S0 moves to G1 X ... S1 moves. S0 moves ignore endstops while moving, so are not suitable for homing moves and probably the reason for the crashing, while S1 moves sense endstops while moving.
This is also how it's setup on the RepRapPro Ormerod 2 github: https://github.com/reprappro/RepRapFirmware/blob/master/SD-image/sys-Ormerod-2/homex.g

That Github was last edited 9 years ago... how time flies!

Assuming you're using a Duet 0.6, you could also update to 1.26.1, the last version of RRF for that board. https://github.com/Duet3D/RepRapFirmware/releases/tag/2.05.1
Check the release notes for changes, though: https://github.com/Duet3D/RepRapFirmware/wiki/Changelog-RRF-1.x-&-2.x

Ian

Sardi

@droftarts Hey Ian mate, I do remember you from the RepRap Ormerod forum, and yes our printers are a bit old now but they still do the work

What I forgot to mention is - I tried all sorts of combinations wihtin the Gcode including the change from S0 to S1 and, in the lack of options, even to S2 - nothing changed.

Whatever I did, whatever I tried, there was no change.
I have a spare Z probe, but this one does react to the white paper, so Im not keen on replacing it.

I have also copied the homex.g from the github to my homex.g just to be sure, but to no change in behaviour.

Maybe worth mentioning that I have replaced the original Z rod with the T8 threaded leadscrew rod that took away some space but still, the probe reacts to the paper, it just doesnt stop when it does.

Regarding the firmware, I might try the jump to 1.26 and see if it will work. I did once install some firmware higher than 1.20 but have heavily disliked the web control, so I went back to 1.20

So If you have any more ideas, Im listening, otherwise Ill go back to manual homing

droftarts

@Sardi Hi! I thought I recognised the name. Unfortunately I don't have an Ormerod to test on, I didn't swipe one when RepRapPro shut down! I did get a Fisher Delta, which has been lightly modified and is still in use. One day I'll find a use for the couple of Duet 0.6 boards I have kicking around!

If you update to later than 1.20, you can still use the 'classic' DWC. From memory, I think you go to the printer IP address, with /reprap.htm after, eg `192.168.0.10/reprap.htm'.

You definitely need G1 X ... S1 moves instead of S0. It might be that you don't need to change the probe type to type 1; I think that was only done because the response was faster as a type 1, while type 2 had to average the signals (it was only marginally slower). You might need to set up the full parameters for M558 and G30, though if Z homing is working. Have a look at @dc42's Ormerod config here https://github.com/Duet3D/RRF-machine-config-files/tree/master/Ormerod_1/dc42-maestro-centrezero-dc42sensor-dualNozzle/sys
While this has a Maestro rather than Duet 0.6, it looks like it is on RRF 1.x or 2.x (effectively the same), and uses an IR probe for X axis homing.

Ian

Sardi

@droftarts you wont belive what was behind my problem

So, everything is set as it should be but still the X carriage hits the rod. I start digging and eliminating probable causes. I get to the probe itself. I click home x while holding my finger near the probe - it stops upon reaching my finger and now I start to wonder - whats the difference???

As it turns out, the difference was that my finger was closer to the probe than that piece of paper.

When the probe would get to the paper, it would detect the value of about 500, when It got to my finger, the value was arround 900 and that triggered the probe well and good.

It was the bloody distance from the Z probe to the paper. For some reason, 500 was not enough for it to send the signal back home that it reached the end stop.

This is how "close" the paper was to the probe before.
Senzor slika2.jpg

Now I turned the orange x stop bar so that the longer part is up over that black thingie and now the probe stops when it detects the x stop bar.

But also makes me wonder - 500 value wasnt enough, 900 was. Does this have anything to do with the probe itself, or maybe with the firmware? or a certain config.g setting? Maybe something is telling the probe that 500 value does not mean there is an endstop, but 900 does.