Mach 3 homing

[johnboy48]

I have fitted homing switches to my machine but it triggers the switch but does not reverse far enough to disconnect the switch. How do I increase the reverse distance? The button script just says "do button 24" etc

TIA

John

[Lee Roberts]

Hi John welcome to the forum!

As far as I know there isn't a setting for back-off distance, it should work that the axis will "back off" until the switch changes state. You would normally set the axis position of your choice at this point in your button VB homing code etc.

For instance, when I push the Ref-All-Home button on my setup, all axis go to the switches, they back off the switch, then they go to a specific place on the machine bed that I then use as my main home/zero point....I then program everything in CAD from that zero or WC etc. Works great.

What code do you have in your "Ref-All-Home" button?

You could have a software problem with the Mach3 install, so either a software issue in that case re-install Mach then the button code, make sure you save and exit when doing button code edits.

If its a hardware issue, is it possible you have an electrical noise problem (false signal etc), or could it be a bad/faulty switch?

[johnboy48]

Thanks for the reply and welcome. It does "back off", just not far enough to reset the switch. It does the same on all 3 axis so not a switch problem. If I manually press the switch and release as it is backing off it completes and starts to home the next axis but does exactly the same thing on that axis.
The button script is -
DoButton( 24 )
DoButton( 23 )
DoButton( 22 )
DoButton( 25 )

DoOEMButton(133)
DoOEMButton(134)
DoOEMButton(135)

I can't find a way to edit these commands.

I set the "debounce interval" in general config to 1000.
John

[Lee Roberts]

Ok John, I'm going to my workshop later today I'll grab you a copy of what my code is so you can learn from it, probably be later tonight or maybe tomorrow when I post it...

[johnboy48]

Thanks Lee, I appreciate it.

John

[johnboy48]

Found the problem. Under "plug in control" in the menu bar there is an option to select my control board. In that are options for how far each axis backs off once the switch is triggered. It now trips the switch, backs of rapidly then trips the switch again but very slowly for more precision then backs off again and sets zero.

[Lee Roberts]

Excellent, I was going to post today to say:

Sorry for the delay, after looking at my homing code I realised I was getting my scripts mixed up and thinking of the auto tool zero script rather than the homing, the homing by default is very basic and probably what you already have for that button code. So I was going to suggest my first post still apply, hardware/software issue.

Out of interest what control board do you use, also have you just installed/reinstalled Mach3 and that's why your card wasn't selected or something else?

[johnboy48]

I am using a cheap USB board. I was running without limits/homing switches just using soft limits but after a couple of crashes due to operator error decided to fit them. None of the videos I watched showed having to change any settings other than the inputs and homing limits under the config menu. I guess they were using a parallel port board where you don't have to change anything? The board was selected, just needed to change the settings for the back off distance, it was set to 0.5mm which was not enough, changed to 3mm and it works fine.

Board I am using - https://smile.amazon.co.uk/100Khz-Br...-4-spons&psc=1

[Lee Roberts]

Yea gotta love hardware limits to save the day, not sure what video you watched but more than likely a PP bob, my next questions would have led us to this so well done for working it out and saving us both a bunch of time troubleshooting :)

Now that's sorted what do you plan to make first ?

[johnboy48]

When I had the problem I watched quite a few videos to try and find the solution but none mentioned editing the plugin for the BOB. Finally found it by just going through every menu and trial and error. All part of the fun of a homebuilt machine I guess.

No real plans for making anything at the moment, I built the machine more as a project to see if I could actually make it work than anything else.