Author Topic: Limit/estop switch wiring; coolant pump suggestions  (Read 3827 times)

landon303

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Limit/estop switch wiring; coolant pump suggestions
« on: August 05, 2016, 08:01:33 PM »
Hey all!  I have a Microkinetics CNC retrofit kit on a BP clone mill, and I went PMDX to avoid their proprietary software in favor of Mach 3, which I'm already familiar with on a CNC plasma table.

On my plasma, I used these switches for home switches, so that I could square the gantry which has the Y & A axis slaved to each other.  http://sensing.honeywell.com/BZ-2RW822-A2-Premium-Large-Basic-Switches

I bought 6 of them for the mill, hoping they're the right ones for the PMDX board.  Will be using them for X Y & Z limit switches.  I'm confused I guess on how to wire, it sounds like everything will be in series, run in an NC config, and when I hit the limit of travel for any axis, all 3 motors will hault?  Or?  I'm lost at the logic, on the plasma each switch went to a seperate spot on a board in the control box, but they were for homing of course.  I guess what I'm asking is, how does the machine act when any of the switches are triggered?

Is the Estop tied into this same circuit, too? or is it stand-alone?  Ahh sorry I just can't wrap my head around it haha

Lastly, for a coolant pump, I'm curious if you have a model of pump that you can point me to? 

That's all for now, thanks so much for the help I'm so close to making chips, and am very excited!

Landon

Bob at PMDX

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Re: Limit/estop switch wiring; coolant pump suggestions
« Reply #1 on: August 06, 2016, 01:54:32 AM »
As for models of coolant pumps, I'll leave that for Steve or anyone else here.

Looking at your user name and our order history I'm guessing that you have a PMDX-126, correct?

There is a separate, dedicated EStop input on the PMDX-126 on connector J13.  Your EStop circuit should be connected there, between the "E-Stop' terminal and the adjacent "GND" terminal if your EStop switch is normally closed, or between the "Fault" input and the adjacent "GND" terminal if your EStop switch is normally open.  We DON'T recommend using normally open contacts for EStop because if the wiring comes loose or breaks somehow you will never know it until your machine DOESN'T stop when you hit the EStop switch.

For your limit switches, it *is* possible to wire them all in series to a single input on the PMDX-126.  However, if you do you will have to enable "limits override" to jog off any of the limit switches since Mach3 can't tell which limit (positive or negative, Z, Y or Z) was tripped.

Will any of these also be used as a home switch?  Do you have any other input signals that you need to connect, like a touch probe?  If you also want to use, say, the minus limit switches as home switches, we usually recommend wiring each limit/home switch to its own input.  You can then gang the three positive limit switches to the 4th input.  With this arrangement Mach3 can home all 3 axis at the same time.  Not necessary but a little quicker.

If you also need a touch probe or some other input signal, you have a couple of options:
(1) Wire all 3 negative limit/home switches to one input, all 3 positive limit switches to a second input, leaving 2 inputs available for other uses.  Mach3 will have to home 1 axis at a time.

Or...

(2) Use "Expanded Inputs" mode to give you 8 inputs instead of 4.  The drawback to this is that if you have the "charge pump" feature enabled on the PMDX-126 (which we recommend when connected to a PC's parallel port), you will not be able to see all 8 inputs when Mach3 is disabled ("Reset" button is flashing).  They will only be available when Mach3 is enabled since the charge pump signal is used to multiplex the 2 sets of 4 inputs into Mach3.

Bob
Engineering Hell: Everything's right and nothing works.
Bob's Corollary: If everything's right and nothing works, double check your assumptions.

landon303

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Re: Limit/estop switch wiring; coolant pump suggestions
« Reply #2 on: August 06, 2016, 03:05:18 PM »
Bob, awesome, all great info!!  Thanks so much for the quick reply, too!  And yes you're correct, I have a PMDX 126 & a 107 spindle daughter board.  Sorry, should have mentioned that in the first post.

I hadn't even thought about a probe until you'd mentioned it just now, thanks!  Ahh I have so much to learn.  I spent a good bit of time today watching videos & reading up on them, but, do you have a certain model probe you recommend/sell in the store?

Think that's it for now, thanks so much for your time!

Bob at PMDX

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Re: Limit/estop switch wiring; coolant pump suggestions
« Reply #3 on: August 06, 2016, 05:35:49 PM »
I'll leave probe (and coolant pump) recommendations to others.  I stay strictly on the (digital) electronics side of things.

Bob
Engineering Hell: Everything's right and nothing works.
Bob's Corollary: If everything's right and nothing works, double check your assumptions.

landon303

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Re: Limit/estop switch wiring; coolant pump suggestions
« Reply #4 on: August 10, 2016, 11:43:14 AM »
Right on, thanks again!  As I waited, I did more searching, and I think a pneumatic mist coolant system w/ a solenoid valve is more in line w/ what I need.  That said, I assume I just need some sort of 120V solenoid? Wiring up the limit switches today now that they're all mounted, hope to be cutting by the weekend, if not sooner!! Thanks again for all the help, though minimal it's been tremendous for me.  Cheers!

Steve Stallings

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Re: Limit/estop switch wiring; coolant pump suggestions
« Reply #5 on: August 10, 2016, 12:19:10 PM »
Automatic misting systems usually have an air valve to turn them on and off.

This valve can be any voltage, but 24 VDC and 120 VAC are commonly available.

The relays on the PMDX-126 would be suitable to control either voltage valve.

Mist is usually assigned to the M8 code, with M9 turning it off.
Steve Stallings
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