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HELP Mach 4 Not Backing Off Enough After Referencing Machine
« on: November 25, 2018, 01:50:02 PM »
So my router has been working for some time with Mach 4, but I never hooked up the limit switches until now. They work during normal use, but when hitting Ref All upon start up of the machine its not backing off the limit completely. So it will home Z, then X, then start to do Y and then fault out from a limit switch being tripped. They're just regular snap action switches that I've used on a ton of systems.  It's weird because Mach 4 in another of my machines with the same Pokeys 57CNC board works fine.

P.S. Search function is not working and I couldn't find anything by looking manually.

Any help would be appreciated.
Re: HELP Mach 4 Not Backing Off Enough After Referencing Machine
« Reply #1 on: November 25, 2018, 04:37:54 PM »
Hi,
to my knowledge when Mach is referencing it advances to the home switch until it activates then it reverses direction and backs off until
the switch deactivates, at that point the axis is referenced and the machine can now proceed to the next axis in sequence.

Are you saying that the axis does not back up at all or just not enough?

The only thing I can think of is that the switch or switches have insufficient hysteresis. They back off until the switch deactivates per
normal but the slightest vibration cause the switch to re-activate some short period of time later causing a limit fault.

Can you devise a means of testing this?

Another possibility to solve the problem, it would mask the issue at best, is to use the back-off feature that is provided by the PoKeys plugin.
If a certain back-off distance is applied immediately after the axis is referenced then you can back it off such a distance that no subsequent
vibration would cause the switch to activate.

Craig

My wife left with my best friend...
     and I miss him!
Re: HELP Mach 4 Not Backing Off Enough After Referencing Machine
« Reply #2 on: November 25, 2018, 04:45:25 PM »
Hi,
I suppose I forgot to ask why you have combined the limit and home switches anyway?

The 57CNC has a swag of inputs you could have three separate home switches and six separate limit switches and still have plenty
of inputs.

The limit switches are just that, they activate ONLY if the machine is out-of-bounds, they do not activate when referencing.
The home switches activate WITHIN the machine boundaries but are only used during referencing. If they were to activate
as a result of a machine excursion that approaches a limit (without activating the limit) so what? The unintended activation
of a home switch is not a fault.

Craig
My wife left with my best friend...
     and I miss him!
Re: HELP Mach 4 Not Backing Off Enough After Referencing Machine
« Reply #3 on: November 25, 2018, 07:23:44 PM »
Interesting. Ok I've had problems with the limits tripping on this router due to vibration, best guess, every once in a while. It hasn't done it in years. Could be bad switches, but the X Switch definitely worked for referencing then when it backed off it didn't back off enough to reset the switch. I know because I push on the switch lever and it didn't click.

So assuming Mach works the way you explained then I'll see if  I can find the root problem, I don't want to mask it with my Pokeys software.

I already had the machine setup for the X- and Y- for limits and home when I was running Mach 3, I don't see any need to change it now.

Thanks for the help.
Re: HELP Mach 4 Not Backing Off Enough After Referencing Machine
« Reply #4 on: November 25, 2018, 08:00:57 PM »
Hi,
that sounds a bit screwy. Mach should back off UNTIL the switch de-activates. Its the change from active to inactive that does the business.
There should be no way that the referencing routine should continue past that instant UNTIL the switch deactivates.

I don't know what switches you are using....I luv these suckers:
https://nz.element14.com/honeywell/bzc-2rq18-a2/switch-basic-top-roller-plunger/dp/1525198
I use them as home switches and get 0.02mm repeatability. Three home switches each on their own input. Perfect homing every time. No messing around with
limit switches triggering unwantedly.

May I suggest try using your existing switches as home switches only, it only takes a moment to do in the PoKeys plugin, just disable the limit. Then try it again.
Bet you'll have no issues homing then.

Craig
My wife left with my best friend...
     and I miss him!
Re: HELP Mach 4 Not Backing Off Enough After Referencing Machine
« Reply #5 on: November 27, 2018, 05:45:30 PM »
Joe, thanks. That worked! Weird that it didn't work the other way as Pokeys has a drop down for use -Limit as home. Not to mention the fact that this is exactly how I do it on my lathe and never had a problem.