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MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« on: February 08, 2018, 04:03:34 PM »
Hey all, I have a 4x8 cnc plasma running off Mach3 and a gecko g540. I don’t have any limit
Or home switches and I need at least 2 on the Z axis for the PROMA. I need help please.

http://openbuildspartstore.com/micro-limit-switch-kit-with-mounting-plate/

I have these 2 switches, and I kind of understand the wiring. Where should I move toward next?
I need to mount them still as well.

Also I have my PROMA wired and it is reading voltage, I just need to wire it up to the g540 after I get
The 2 Z axis limit switches working.

Any help would be appreciated
Thanks
Re: MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« Reply #1 on: February 09, 2018, 01:14:05 AM »
Hi,
are you looking for home switches or limit switches?

I know a lot of people combine the two jobs but there are some good reasons why that is not the best. It used to be that because we all had only parallel ports we
had to economise on inputs. With external controllers offering many more inputs you don't, in fact probably shouldn't do that today.

My recommendation for home switches are Omron or Honeywell Roller Plunger microswitches. They offer good repeatability and accuracy and can be mounted within
the machine boundaries thereby freeing the very ends of travel for the limit switches.

http://www.machsupport.com/forum/index.php/topic,36285.msg248575.html#msg248575

Craig
My wife left with my best friend...
     and I miss him!
Re: MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« Reply #2 on: February 09, 2018, 02:29:36 AM »
I’m trying to put 2 limit switches on my Z axis only. I have 4 available inputs on my g540 so I’m not worried about space.

 
Re: MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« Reply #3 on: February 09, 2018, 02:48:23 AM »
Hi,
OK, those switches I linked to can be used as limit switches as well but are fairly sizable. The ones you pictured will work OK.

Another possibility is inductive proximity sensors, they can make for a tidy and robust installation.

No matter what switches or sensors you use you should give some thought to what happens if the axis runs away. Trust me it DOES happen!
Any switches/sensors in the way are going to get crunched, may not be the end of the world but certain arrangements or mountings mean that even
a runaway axis won't break them.

Craig
My wife left with my best friend...
     and I miss him!

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Re: MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« Reply #4 on: February 09, 2018, 03:00:26 AM »
i think you are talking about PROMA THC.

on the PROMA Homepage:

http://proma-elektronika.com/index.php/en/products/thc-torch-height-control/compact-thc-150

are wiring digramms and Videos avalaiable as well.

i would start with tis stuff.
anything is possible, just try it.
if you find some mistakes, in my bad bavarian english,they are yours.
Re: MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« Reply #5 on: February 09, 2018, 01:52:28 PM »
Hi,
OK, those switches I linked to can be used as limit switches as well but are fairly sizable. The ones you pictured will work OK.

Another possibility is inductive proximity sensors, they can make for a tidy and robust installation.

No matter what switches or sensors you use you should give some thought to what happens if the axis runs away. Trust me it DOES happen!
Any switches/sensors in the way are going to get crunched, may not be the end of the world but certain arrangements or mountings mean that even
a runaway axis won't break them.

Craig

Thanks Craig, i appreciate the input. i will have a look at the switches you linked. also im not worried about the Z axis running, i have some physical stops that will not let it go further than i want it.

Re: MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« Reply #6 on: February 09, 2018, 02:07:42 PM »
Hi,
OK, those switches I linked to can be used as limit switches as well but are fairly sizable. The ones you pictured will work OK.

Another possibility is inductive proximity sensors, they can make for a tidy and robust installatio

No matter what switches or sensors you use you should give some thought to what happens if the axis runs away. Trust me it DOES happen!
Any switches/sensors in the way are going to get crunched, may not be the end of the world but certain arrangements or mountings mean that even
a runaway axis won't break them.

Craig

Can you explain to me exactly how limit switches need to be wired in?
Re: MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« Reply #7 on: February 09, 2018, 02:41:36 PM »
Hi,
its common practice to wire all the limit switches in series with normally closed contacts. When any one switch operates the continuity of the switch string is broken and
that is what Mach detects. There again its common, but not universal to have Mach Estop on a limit event.

Large and powerful machines are even more safety oriented and a limit event will cause the axis drives and spindle to de-power. When a machine de-powers in such a manner
it is a time consuming matter to restart the machine, assuming no damage is done, and pick up where the job currently in the machine is and start from there.
None the less safety requires such an arrangement, if the controller has 'brain fade' and the EStop doesn't work or is slow, it is essential that the machine be made safe.
Because of the inconvenience and lost time a great deal of effort is expended to prevent a machine from ever operating the limit switches.

Mach has soft limits. They are programmed usually to be just inside the physical limits and limit switches. The program will detect that you or your Gcode is attempting
to drive your machine out of bounds and stop you. They work really well, but they absolutely rely on the machine being referenced or homed. So when you turn your
machine on and you 'home' your machine it will drive to pick up its home switches in each axis. Mach knows thereafter where it is in relation to the boundaries of the
machine and soft limits become useful.

It is for this reason that I argue that good, reliable, repeatable home switches are more important than limit switches. For about a year or so I operated my mill
without home switches and suffered a few crashes because soft limits didn't work because the machine was not repeatably referenced. Once I got around to fitting
home switches the number of out of bounds moves dropped dramatically. Good home switches were the best addition/development I ever did on my mill not to mention
very cheaply too!

Craig
My wife left with my best friend...
     and I miss him!
Re: MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« Reply #8 on: February 09, 2018, 02:53:16 PM »
What do I need to buy and how do I wire in 2 limit switches to my Z axis only? I have a g540 board and my e-stop is bypassed. It is very simple. I have one single relay, and it is only used to fire my plasma.
Re: MACH3PLASMA LIMIT SWITCHES FOR G540/PROMA
« Reply #9 on: February 09, 2018, 05:03:50 PM »
Hi,
you need two microswitches which can be mounted at the ends of the Z axis. You could use proximity sensors if you wish, but simple and bang for your
buck microswitches are fine.

You need a powersupply, I've shown it as 5V+ in the diagram, but whatever it is on your G540, hooked through the two normally closed contacts to one of your spare
input pins on the G540. Probably a good idea to include a resistor so that you can be sure the input pin goes low when one of the switches opens. Hook a 10k (approx.)
resistor between your selected input pin and earth on the G540.

The input pin can now be assigned as your Z++ and Z-- inputs with Mach3 and they will be active low.

Craig
My wife left with my best friend...
     and I miss him!