[mhackney]

In the process of thinking about wiring an e-stop on my G0704 and how I did it on my X2 I realized I may be making things too hard on myself. Being self-taught I have developed a way of working that may not be the best or optimal. So I thought I would ask those with more experience!

Basically, I run a part time business out of my shop. When I am making parts, I'll make a batch of say 100 of something and then maybe work on the computer to design a new reel or part or make changes or any number of things. This might take 10 minutes or run into several hours. On my X2, I have the e-stop wired to the G540, it does not cut power to the mill. I do have the main power switch right in front of me that I would use in a real emergency. I use the e-stop more like a disable switch than to actually respond to an emergency. In the few times I've had an end mill crash or noticed something going wrong, I hit the e-stop button and things stop moving. I use the e-stop to put the system on stand-by while I'm working on CAD or CAM and then reset and machine when I am ready. I may do this 3, 4 or more cycles in a session.

Now, thinking about my G0704 that I am almost finished converting, I am in "analysis paralysis" about the e-stop and/or system disable functions. So, some questions:

When you operate the mill for short periods, maybe doing something in between, do you shut the main power to the controller and mill off, have some sort of stand-by function (like a disable switch that disables the BOB and drivers) or leave it live and not worry about it? Leaving it live seems a little risky in that the pendant would still be live and if Mach is running and I wasn't careful I could "mill air". Leaving it live also keeps power on the steppers and they get hot just sitting there.

What I am thinking about for the G0704 - and then I'll convert the X2 - is something like:

• implementing a true e-stop that kills power to the supply, BOB, drivers and motors, including the spindle ultimately. I'd have an e-stop button on the mill and another at the workstation.
  
• incorporating an enable/disable toggle switch that disables the BOB (a C35) and drivers (KL6050) but leaves the power supply, fan and 5 & 12 volt transformers powered on.

Does this make sense? How do others work with their machines?

cheers,
Michael

[gd.marsh]

Michael,

I'm certainly not the electrical expert here, but I've just been through all this with my own machine & what I wound up doing is close to what you've described.

I've got two e-stop switches that reset Mach3 & kill AC power the 72VDC PS. That shuts off power to the drives, motors, & also trips a built in relay in the VFD which kills spindle power.

My Bob is powered with 110v & I have a 12VDC supply for some of the various bells & whistles added to the machine. The computer, control box fans, Lights in the enclosure, & power drawbar will all continue to operate with an e-stop.

So If I'm going to step into the house for a while or do something else around the shop I just hit one of the e-stops & I'm in 'Safe Mode'

Gary

[underthetire]

Well, being a hobby machine, you can do whatever you wish. The true code logic for an estop now is...

Must stop any moving part of the equipment, Ie conveyors, coolant pumps etc..

Must disconnect power from servo/axis/spindle drives

must have a mechanical release on the Estop button ie twist to release

Must not be able to re-energize power by releasing the Estop button

Must have a separate operation to re-store power after an Estop (start button, PC enable button, etc..)

Must have a yellow ring around the Estop button, labeling in the US is optional, no labeling for most of europe.

This is the basics of it, i won't bore you with the entire code, since ANZI, NFPA, NRTL and a whole bunch of others have pages of mind numbing details on it.

[Al_The_Man]

What you could do for short periods of stopping the machine and reducing heat in the steppers is apart from the main E-stop as Underthetire points out, is to use the enable input on the stepper drives using a multi-contact relay, and and set up an input as Feed Hold, if using a SuperPID controller on a router spindle, you could also disable this or use a off input in the case of a VFD etc.
Al.

[mhackney]

Thanks guys. Al, that is basically what I have in mind with the enable switch. The stepper drives (Keling) have an active low enable. Seems counter intuitive but that's the way they are. I am planning to use a 7404 IC (hex inverter) with the input line feeding the enable on the BOB (+5 v) and to each of 3 of the inverters, so their output will be low (enabled) when the BOB is +5 (enabled). When the enable line is brought low (open switch) the BOB drops to 0 (disabled) and the 3 inverters to the drivers are brought high (powered from a 5v supply). Ultimately, I can add in spindle disable too.

cheers,
Michael

[SCzEngrgGroup]

Keep in mind, if you're using micro-stepping, using the driver enable *may* cause position loss.... If you're operating your steppers properly, disabling the drives "to reduce heat" is completely unnecessary, and of no benefit whatsoever. Stepper motors are DESIGNED to run hot.

Regards,
Ray L.

[photomankc]

Yep, that's a good point. Mine can drift a bit if you enable/disable a few times. They never snap back *exactly* where they were before. I also agree that concern over the heat is not really something I would be getting too wrapped up in. I have left mine on all day and are just as hot as they normally are after 15 minutes of operation. I'm even overdoing a bit on my 425's by about 500mA.

If I have nothing setup at the moment I'll disable just to keep the electric bill down a bit, but if I have a setup that I can't get right back to I have no qualms with leaving it on for days so I don't have to rezero on a picky part.

[mrcodewiz]

Keep in mind, if you're using micro-stepping, using the driver enable *may* cause position loss.... If you're operating your steppers properly, disabling the drives "to reduce heat" is completely unnecessary, and of no benefit whatsoever. Stepper motors are DESIGNED to run hot.

Regards,
Ray L.

Hmmm... I'm not sure what this means. That's a mach setting? I know on mine that pretty much any time I hit the e-stop that unless every axis is at a standstill, i will lose position.


edited to add - I mean the 'enable' setting. I am using microstepping.

[photomankc]

It's a drive setting too. Mach and the drive must agree on it. When you disable the drives the motor was in some 'in-between' position from the normal 200 full steps that was based on some type of table that the stepper driver was running through. When you re-enable, most drivers go back to a full-step position that they define as their start point and not that 'in-between' phase you were being held in before. That obviously snaps the motor shaft into a position some small amount different from where it left off. Maybe it's a few tenths, maybe a tho but it probably moved a bit. It's most pronounced on my Z where weight tends to be able to back-drive the screw a little each time the stepper's power is removed.


Oh I see your edit. We're talking about the enable input on the drives and switching it, I don't know if Mach has the notion of a seperate 'enable' or not but he's talking about just switching the electical signal to the drives from a panel. Is that what you are getting at?