CNC Question - E-stop wiring

[AndyL]

G'day all,

Quick question - not finding relevant googles... And I can't figure out my cnczone password (and its apparently to an ancient email because I can't find which one it goes to).

Picked up an allen bradley DPDT panic / emergency stop switch; trying to think through the best way to wire it in to the CNC.

I know I don't want to have it operate the virtual E-Stop on the computer...

I'm thinking I want to run the hot wire to the controller and to the router through it (it is 240v 100a). But have question about that - I need to keep my power supplies for the router separate from the controller (ie two different breakers - otherwise I get some kind of interference and missed steps / or steppers doing the jitterbug instead of operating normally) - would running both hot wires through the switch halves be bad in this case? I know they're isolated from each other - but...

Other option I can think of would be to kill the 32v in the controller and 3.3v from the PC to the SSR for spindle control?

I just want to be 100% sure next time my wife needs to hit E-stop because things went wrong - EVERYTHING stops... the virtual e-stop didn't work so good for her last time (axis took a dump on that go-round; it was locked up - one of the SIMMs failed - created a lovely trace in the sacrificial layer and 'lightening hole' in the bed; )

Thanks in advance!

 

[A_Pmech]

Whatever you do, you want your emergency stop button to stop the axis drives before the spindle. Stopping the spindle first is a good way to break things.

Surely the software you're using has an interrupt capability for an emergency stop?

 

[AndyL]

Linuxcnc does - however if the PC crapped the bed - guess what happens... Wait I should uoad the ugly pics...

She knew how to use the onscreen e stop - problem was the computer was locked up solid... So it was having no effect. And then its the panic phone call of the damn machines drilling a hole in the bed went through your clamp on the way how do I shut it down the red x isn't working

In other words yes I want a real "all hell broke loose kill everything" button not a daily use button...

 

[A_Pmech]

Ohhhhhhhh!

That's the downside to PC-based controls. The operating system has some not so desirable traits.

If you're working on things of relatively low value, where recovery from an E-stop isn't necessarily required, I might interrupt power to the axis drives and spindle motor. It's crude as hell, I admit, but it sounds like the direction you're heading.

This, of course, creates the quandary of two E-stop buttons. One for little emergencies and one for BIG emergencies.

 

[AndyL]

Let's put it this way - I'm going to wire in the virtual estop to a simple on/off toggle on the front of the stand (since for some reason it will go into screen saver lately on long cuts) - and mount the Allen Bradley much farther back - in reach, but further away...

Gotta make sure I don't piss off the DW and have her tell me to shut it down if I need to go to work (it never fails - I get something setup finally have a quiet day; hit execute - and the phone rings) so having "if all else fails - hit the panic button" is appropriate - even if it costs me an end mill or two...

The valuable cuts - yeah I'm there... But the little stuff in plywood that takes forever... Nice to let her just run semi-supervised...

 

[brucer]

I dont know your setup, but can you just wire the e-stop directly off one of the pins on the bob?


On my cnc plasma cutter I just have a switch wired inline to my power supply..

 

[AndyL]

Well thats basically the question...

Do I kill the low voltage controls - or high voltage power...

More reading - I probably should just kill the 110v to the pair. Category 0 estop. Then go with the plan run a switch for a category 1 or 2 physical e stop - more of a day to day controlled stop not an oh sh+t panic stop.

Its interesting theres not more use of them on the homebuilts...

 

[brucer]

The reason I didnt wire my e-stop off my bob is I ran out of available input pins. I'm only running one parallel port and one bob..


are you running a router on/off relay from your bob?

 

[casetractorfarmer]

What about one of these on the incoming power
http://www.menards.com/main/electri...neral-duty-safety-switch/p-1773842-c-6435.htm

 

[AndyL]

The only glitch there is like I said - 2 separate breakers power the unit. So needs to be a double pole switch. And do like the big mushroom cap panic buttons. Hard to not see

 

[Kevin54]

Let's put it this way - I'm going to wire in the virtual estop to a simple on/off toggle on the front of the stand (since for some reason it will go into screen saver lately on long cuts) - and mount the Allen Bradley much farther back - in reach, but further away...

Gotta make sure I don't piss off the DW and have her tell me to shut it down if I need to go to work (it never fails - I get something setup finally have a quiet day; hit execute - and the phone rings) so having "if all else fails - hit the panic button" is appropriate - even if it costs me an end mill or two...

The valuable cuts - yeah I'm there... But the little stuff in plywood that takes forever... Nice to let her just run semi-supervised...

Not sure what you are exactly doing, but I would never wire an E-Stop to a toggle switch. The main reason being is that when things start to go wrong, you will not see that toggle switch. Most people can't find the large red button when in a panic. Even if you are 3/4's of the way through a program and have to start completely over, it's easier to kill the power to everything and not risk some more expensive damage and costly repairs.

 

[AndyL]

I'm starting to realize - I dislike terminology used these days...

Ok - machine has a software based estop. And its regularly used in normal practice. Basically turns off steppers and spindle (More like a VCR pause button). That I'm thinking of on a toggle rather than relying on keyboard/mouse.

But I want to add in a real estop - all hell broke loose kill it all now - button.

Testing this morning - running the 2 @ 110v power sources through the switch - theres some kind of interference - machine doesn't operate smoothly like it should. Induction? Unfortunately due to switch design - the wires have to come in / out in parallel. So back to that original question - do I then use the switch to cut the control power - to kill the system - or is there a way to have the 2 110v feeds work through the same switch without this issue? I'd rather have one switch kill all the power to the machine in one press...

 

[ddawg16]

Use the E-Stop to power a relay. The you put the relay close to the power source (120vac)

E-stops don't have to turn off all power. Just remove power from things that are moving.

 

[brucer]

Use the E-Stop to power a relay. The you put the relay close to the power source (120vac)

E-stops don't have to turn off all power. Just remove power from things that are moving.

This is why I asked him if he was running a relay to control his router..

I wasnt going to come right out and tell him

 

[logixjock]

I'm starting to realize - I dislike terminology used these days...

Ok - machine has a software based estop. And its regularly used in normal practice. Basically turns off steppers and spindle (More like a VCR pause button). That I'm thinking of on a toggle rather than relying on keyboard/mouse.

This is NOT an E-Stop, they are hard wired, and use "control reliable" components. In it's simplest form, you will want to use a self monitored safety relay.

But I want to add in a real estop - all hell broke loose kill it all now - button.

This is actually an E-Stop, in an E-Stop situation, you don't worry about protecting the equipment, you worry about putting it in a "people safe" condition no matter what.

Testing this morning - running the 2 @ 110v power sources through the switch - theres some kind of interference - machine doesn't operate smoothly like it should. Induction? Unfortunately due to switch design - the wires have to come in / out in parallel. So back to that original question - do I then use the switch to cut the control power - to kill the system - or is there a way to have the 2 110v feeds work through the same switch without this issue? I'd rather have one switch kill all the power to the machine in one press...

I would recommend a safety relay for each feed, controlled by the E-Stop operator. If you have a PDF of the schematic, and some pictures I can get you started in the right direction. This is what I do for a living.

Jim

Some good reading on the subject.

www.literature.rockwellautomation.com/idc/groups/literature/documents/ca/s117-ca501_-en-p.pdf

 

[ddawg16]

I would recommend a safety relay for each feed, controlled by the E-Stop operator. If you have a PDF of the schematic, and some pictures I can get you started in the right direction. This is what I do for a living.

Jim

From your screen name, I'm going to guess your an AB guy (ControlLogix)

Ya Gota love AOI's

 

[logixjock]

ddawg16,

You're the first one to ever get that reference , until spring of this year I was still pretty old school, cut my teeth on Slc's: multiple processors, multiple networks, wasn't anything I couldn't make work with one. I absolutely hated CLX, then got a half finished robotic forging cell dropped in my lap in May, and was forced to use what was there. I can't believe it took me this long to embrace the new technology. The CLX platform is awesome, UDT's and AOI's are the icing on the cake. I love being able to package a bunch of code in an AOI and just pull it into the code as an instruction whenever I need it.

Sorry OP, didn't mean to jack your thread.

 

[ddawg16]

Yea....I love the ControlLogix and CompactLogix stuff....but I still use a lot of the RS500 stuff...specifically, the Micro 1100 and 1400.

In one case, I'm using a 1400 to talk to some Honeywell UDC's via Modbus (One of the ports will do RS485) and the other serial port controlling an Agilent 34970A via RS-232 and my computer talking the 1400 via Ethernet. Reliable and does away with a lot of the external converters and other misc BS.

I haven't done any motion control stuff with the CLX platform yet....Siemens for the most part has the segment locked up.

 

[Abj87]

All of our machines the e-stop stops the axis motors and locks the sound.

Sent from my SCH-I545 using Tapatalk

 

[Abj87]

I'm starting to realize - I dislike terminology used these days...

Ok - machine has a software based estop. And its regularly used in normal practice. Basically turns off steppers and spindle (More like a VCR pause button). That I'm thinking of on a toggle rather than relying on keyboard/mouse.

But I want to add in a real estop - all hell broke loose kill it all now - button.

Testing this morning - running the 2 @ 110v power sources through the switch - theres some kind of interference - machine doesn't operate smoothly like it should. Induction? Unfortunately due to switch design - the wires have to come in / out in parallel. So back to that original question - do I then use the switch to cut the control power - to kill the system - or is there a way to have the 2 110v feeds work through the same switch without this issue? I'd rather have one switch kill all the power to the machine in one press...

Two questions here...

Why would you want to stop both in the middle of a cut? We use feed hold then turn off the spindle and the reverse when starting again. Starting and stopping both simultaneously damages the tool.

What kind of machine comes without a hardwired e stop?

Sent from my SCH-I545 using Tapatalk

 

[AndyL]

Well... Like I said in case of hardware failure (which we just encountered) machine decided to fail in a x,y,z going to -infinity and disregarding limits.

I'm sure pro level equipment this isn't an issue - for hobby level it is... Few DIY routers seem to even run one; I know searching I found lots on how to tie into the software estop - but that assumes controller and PC are still live. Little on a true failsafe.

Ive got a 25amp SSR to control router on/off, but power to that comes from PC parallel port.but yeah, 5vdc wall wart to switch to a pair of SSRs to kill the power to the pair of feeds would probably be smartest and simplest.

 

[LutzTD]

on my control which is copied from the Bridgeport Boss I am wiring the power for the geckos and the spindle relay through a relay that is normally open. The relay has to be powered to run everything, then the axis overtravel switches and E switch are in series normally closed. If you hit an axis stop it opens the relay and kills everything, same as if you hit the e-switch. then you have an overide momentary that powers the same relay to pull back from an axis overtravel. On my control I also plan to have lights to show which switch is open so that if it hits an overtravel I will know for sure which one to traverse to bring it back.

 

[brucer]

What kind of machine comes without a hardwired e stop?

Sent from my SCH-I545 using Tapatalk

I would guess about every cnc machine tool thats been manufactured in the past 40yrs.. They all kill power to the spindle/spindles and drivers..

 

[brucer]

Well... Like I said in case of hardware failure (which we just encountered) machine decided to fail in a x,y,z going to -infinity and disregarding limits.

I'm sure pro level equipment this isn't an issue - for hobby level it is... Few DIY routers seem to even run one; I know searching I found lots on how to tie into the software estop - but that assumes controller and PC are still live. Little on a true failsafe.

Ive got a 25amp SSR to control router on/off, but power to that comes from PC parallel port.but yeah, 5vdc wall wart to switch to a pair of SSRs to kill the power to the pair of feeds would probably be smartest and simplest.

When I wired my cnc plasma, all I had to do was kill power from the power supply that feeds the drivers... I used a regular 110v light switch, simple on/off.. pretty sure I could wire the router relay through the same switch if I were using a router..

Seems like you could wire the estop and router relay directly from an input pin.. actually If I'm remembering correctly mach3 uses pin11 for e-stop by default, it's basically set up like a limit switch. Why cant you control the router relay through that same switch?


If your machine just took off, and disregarded your limits switches, you have something else going on..

 

[oldestof11]

While we don't have CNCs where I work, we do have complex machinery that have people working with them (food packaging). Each E-stop interrupts the control voltage for the main power contactor. This then stops all power coming in. So putting a contactor before the feeds for the drivers and spindle should work.

I should add, we have 2 sources of disconnects on the machines, electrical and mechanical.