Reply with QuoteYou may not feel the "need" for one but you sure will want one when it all goes pear shaped. My answer is yes to the "need" and it should arrest all movement of the machine. Spindle, steppers and or Servos.
Do I need an E-Stop switch?
I "think" I understand the purpose of an e-stop, but I'm wondering if need one. I have yet to do a test run on my new machine- still putting everything together. I have a Gecko G540 and it's power supply is plugged into a rackmounted power switcher (like the kind touring musicians use). I have a dedicated (lighted) toggle switch to turn the Gecko's power supply on/off. I ran a straight wire from terminal 10 to "-" on the power supply. I get my green LED to light up on the 540, and when I flip the power switch, I get an instant red (fault) LED. Is this the same functionality of an e-stop? FWIW, the switch I use is easy to see, marked, and always within quick reach...am I good to go, or am I missing something, here?
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Re: Do I need an E-Stop switch?
You may not feel the "need" for one but you sure will want one when it all goes pear shaped. My answer is yes to the "need" and it should arrest all movement of the machine. Spindle, steppers and or Servos.
Re: Do I need an E-Stop switch?
The Pin 10 to ground connection on the G540 is specifically designed for wiring in an NC E-Stop.
cheers, Ian
It's a state of mind!
Re: Do I need an E-Stop switch?
Is there an e-stop hierarchy? The e-stop that would replace the jumper (from ground to pin 10) on my board would be an e-stop for what exactly? Just the board? Isn't killing the juice to the board's power supply doing the same thing? Would I be better served with a "master" e-stop that killed everything (except the system computer)?
Re: Do I need an E-Stop switch?
Yes, the E-Stop connected as recommended will cut power to the drivers and steppers, and thus all movement.
I'd highly recommend checking the G540 manual wiring diagrams, the guys there are sufficiently advanced in my books that if they recommend the E-Stop be wired there, then that's where I'd put it.
That doesn't stop you adding others, or bypassing it, but if your doing this then you need to be aware of the tremendous voltages that can be generated as the fields collapse, which can result in backfed current, that if it isn't properly snibbed or bypassed, can and will destroy a driver depending on how it's wired.
Myself, I'd just have as many NC E-Stops as I want or are required, installed in series as described, and a separate toggle switch for the power supply.
cheers, Ian
It's a state of mind!
Re: Do I need an E-Stop switch?
Ok, Ian. Good points....it's cheap insurance to wire it in. I'll do it this evening. Thanks.
Re: Do I need an E-Stop switch?
I've never really had to use an E-Stop in anger except for one time when I thought I'd click the "calibrate" button to see what it would do, and the spindle immediately started to force it's way to China, I was very glad for it then!
I don't even want to think what damage the rails, drivescrew or frame would have suffered with a 300kg machine trying to bore downwards without limit!
It's the kind of thing you may never need, but if a time ever came that you do need it and don't have it.....!
cheers, Ian
It's a state of mind!
Re: Do I need an E-Stop switch?
The E-stop button is the hardest one to find on a panel!
The problem with incorporating the E-stop in a hobby built machine is that every part supplier has some kind of instruction for e-stop of his particular unit or system, the result is that often a proper or complete E-stop is never done correctly or completely safely.
As some one who retrofits CNC for a living I have to conform to NEC and NFPA79 and for some decades there has been a general common practice in effect, regardless of the make and model of systems.
There has been at least three similar posts in the past couple of weeks on this issue.
One here.
http://www.cnczone.com/forums/genera...-software.html
Al.
Last edited by Al_The_Man; 12-03-2014 at 10:22 AM.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: Do I need an E-Stop switch?
You will want one when your machine decides to dive into the bed/vise/part or something worse.
Re: Do I need an E-Stop switch?
Ah....this explains my confusion perfectly. My Gecko 540 board has an E-stop requirement, but I also have a drive system (Ethernet smoothstepper- SSENC-2 from Soigeneris) and that has one, too. They seem redundant, to me. Actually, in a moment of panic, it might be confusing. eg: "Which E-stop do I push!!???" The SSENC unit I bought has an E-stop built in with the ability to wire up to 9 amps (max) worth of downstream gear. That would be enough for my Gecko's power supply. I'll keep my jumper (E-stop bypass) on pin10 of the Gecko G540 (no E-stop), and allow it to be handled by the "master" E-stop in the SSENC. My switching rack will have all my other associated gear- vac/DC, computer, monitor, etc...none of which requires an E-stop. Sorted.Originally Posted by Al_The_Man
The E-stop button is the hardest one to find on a panel!
The problem with incorporating the E-stop in a hobby built machine is that every part supplier has some kind of instruction for e-stop of his particular unit or system, the result is that often a proper or complete E-stop is never done correctly or completely safely.
Al....maybe. lol
SSENC driver doc:
https://www.soigeneris.com/Document/...ers_Manual.pdf
Re: Do I need an E-Stop switch?
STOP!!!"Which E-stop do I push!!???" The SSENC unit I bought has an E-stop built in with the ability to wire up to 9 amps (max) worth of downstream gear. That would be enough for my Gecko's power supply.
This is still not proper. You do NOT want to cut the power to the drives.
Think about it. If you cut all power to the drives, then you can kiss the Regen braking good bye. All E-stops keep the computer up and all the drives running, but they have their pulse/direction or 0-10V signals halted until the situation is looked after or a proper reset is made. The drives will wait for this reset before accepting anymore signals from the computer.
That is the proper way to do it.
Yes and also, everyone has a master switch to completely remove power from everything.
Please take this advice seriously as to NOT just cut the power off. It is an unsafe practice commonly done by the hobbyist.
Re: Do I need an E-Stop switch?
...good to know, thanks. Maybe I'll just bypass the NC E-stop in the SSENC and use it for the Gecko's recommended "pin10" E-stop. That way, I'm only killing signal and not power...and I'm not looking at more than one red button to hit in a panic.
Re: Do I need an E-Stop switch?
I have been installing commercial systems and CNC controls for 40+ yrs and abide by the normal practice and applicable electrical code, and both of these require the power be dropped to all powered motors, and applicable outputs. per NFPA75.
Servo motor do not have regen braking, the control is purely electronic and tuned via the PID loop.
If it was the case, the regenerative braking action would be turned off as the Mosfet/IGBT outputs would normally be turned off using the enable pin.
Some spindle controllers and VFD's have the ability to keep the low voltage live when shutting of the main DC supply, this supply also take some time to decay, whether E-stopped or not and in the case of a spindle allows the regen brake to still be effective.
Such things as router spindles should also have the power removed immediately.
Normally there is only one E-stop string for all eventualities.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: Do I need an E-Stop switch?
I'm not doubting your expertise here Al, but in the case of the spindle, yes you want the drive to remain energized. If properly connected, the drive disables all outputs, but maintains the Regen braking circuit active, such as on the AMC100A40. That's what I was eluding to.I have been installing commercial systems and CNC controls for 40+ yrs
Another excellent system is the Viper 200 drives. When properly connected to receive an E-Stop signal, the drive stops everything but still remains active. It just disables any output.
That's all I was trying to say.
Imagine getting your hair caught in a large spindle, somehow you manage to hit the E-stop, and now you have to suffer the spool down of the inertia built up in the spindle, because you cut all power to the drive?
Non sense.
Re: Do I need an E-Stop switch?
But the AMC100A40 has regenerative braking and when the inhibit input is used, this turns off all of the output power devices** which would render them inoperable as far as Regenerative braking components?
The 40AC version has a dynamic braking feature which would be active even if the outputs turn off?
Al.
**AMCB100A manual.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: Do I need an E-Stop switch?
Understood,
but what I thought I read here, was the suggestion, of the E-Stop throwing off the big switch therefore killing all power to the machine. That's a big No No.The SSENC unit I bought has an E-stop built in with the ability to wire up to 9 amps (max) worth of downstream gear. That would be enough for my Gecko's power supply.
NFPA75 mentions that when the outputs are disabled, it must be in a controlled state. Just unplugging the machine, well that doesn't cut it.
What the OP should do, is wire the E-stop button directly to his drives in parallel, and get rid of that jumper idea.
Re: Do I need an E-Stop switch?
Nope. Just stop the motion control and the spindle. That can be done without killing the master power.
Re: Do I need an E-Stop switch?
NFPA79 et al mention it is 'Possible' depending on circumstances to do a controlled shut down in some circumstances, not 'Must'.
The controller and usually input devices are no problem retaining power in E-stop.
I still endorse the common hard wired AND'ed function E-stop where possible and the end result is a control relay that removes power from all motorized devices.
The problem I see is that many here are marrying several pieces of equipment together where the supplier is of course is only concerned with with his unit so the uninitiated builder ends up will all kinds of separate individual instructions, similar to the common recommendation to keep the units power, earth ground isolated, as many past posts here have shown, this often leads to spurious noise and false triggering of inputs.
After 11yrs moderating here and over 20k posts I have pretty much run the gamut of beginners problems.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.
Re: Do I need an E-Stop switch?
Yup, you are right. I just E-Stopped my mill here, and sure enough it drops the XYZ drives contactor (relay). The AMC drive to the spindle is still energized but flashing an error and halting all outputs thereby stopping the spindle from 6000RPM to 0 in under a second.
Re: Do I need an E-Stop switch?
So that may explain how I burnt up 3 drivers in 5 minutes, using the estop as a master (BOB, Power Supply, fan and LED transformer, all three drivers etc..) on/off switch ?
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