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Author Topic: AC Servo Spindle and ESS  (Read 6213 times)

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Offline Dan13

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AC Servo Spindle and ESS
« on: April 14, 2015, 03:10:44 AM »
Hi,

Have fitted an AC servo to a large spindle (380mm chuck). It uses an ESS as a controller. Trouble is, when spindle runs, hitting the Stop in Mach causes an abrupt stop of the pulse train to the servo drive and it instantaneously stops. With a chuck that big, it means tearing the belt and causing other damage. With the USB SS it has never been an issue (have it on two machines) and hitting Stop still smoothly decelerates to a stop.

Hood, I am sure you encountered this on your Computurn with the large chuck prior to switching to CSMIO. How did you solve this?

Thanks,
Dan

Offline Hood

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Re: AC Servo Spindle and ESS
« Reply #1 on: April 14, 2015, 03:52:49 AM »
Still have the ESS on the big Lathe Dan, would love to have the IP-A on it but that will not happen until threading with it can pull out instantly.

Ok the ESS has issues with the spindle and that is one of them, press feedhold and axes stop then press Stop and as you say spindle just suddenly stops with no deceleration and on lathes with big chucks that is not nice. The SS used to do it as well but Greg fixed that but for some reason it was introduced back with the ESS and  it was never fixed.
 I have got into the habit of pressing my spindle off  button before I press Stop, occasionally I still forget though and it is not nice :(

Hopefully you may have more luck getting Greg to fix it than I did.

Hood

Offline Dan13

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Re: AC Servo Spindle and ESS
« Reply #2 on: April 14, 2015, 04:31:01 AM »
Oh... thought that threading issue with the CSMIO had been resolved.

Mentioned it to Greg a few times in the past, but as I recall he didn't know how it was different from the SS. He said he was pursuing the original Mach's behaviour and thought this was the normal behaviour it. On the small lathe I too have the habit of turning the spindle off prior to Stop, but sometimes I forget which is not a big deal - it's not nice as you say. However, with this machine, it is much more than being merely not nice with a chuck weighing more that 70kg.

As a workaround I could probably send a signal from Mach upon a Stop (or Reset) hit, to the Servo Emergency Stop input. Somehow, hoped you might had a more elegant solution for this after years of use ;)

Anyway, will talk to Greg again, and unless he can fix it real soon, will have to switch to CSMIO.

Have you switched to Mach4 on any of your machines, by the way?

Thanks,
Dan

Offline Hood

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Re: AC Servo Spindle and ESS
« Reply #3 on: April 14, 2015, 04:54:14 AM »
I gave up on hoping Greg would solve the spindle issues with Step/Dir spindles :(

Threading in CSMIO works great with the exception of the delay at the end of each pass, that may not be an issue for some but for most of the threads I do an annular groove is not acceptable.

No don't have Mach4 on any machines, had been trying it on the wee lathe but the CSMIO plugin and for that matter Mach4 on a lathe is not great, waiting on an updated plugin but that seems to be taking a while.

I do not feel Mach4 is good enough yet to risk testing on the Chiron or the big lathe and the Beaver Mill has a USB SS on it and as far as I am aware it is only the ESS that has a Mach4 plugin.

Hood

Offline Dan13

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Re: AC Servo Spindle and ESS
« Reply #4 on: April 14, 2015, 06:53:13 AM »
Thanks Hood.

Dan

Offline Jeff_Birt

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Re: AC Servo Spindle and ESS
« Reply #5 on: April 14, 2015, 08:18:09 AM »
In Mach 3 when you hit 'Stop' the output immediately stops, you get no deceleration. I'm not saying that is desirable but that is how it works. If you hot 'Feed Hold' you get a nice deceleration to a stop. Always use 'Feed Hold' and once the machine has halted then hit 'Stop'.
Happy machining , Jeff Birt
 
Re: AC Servo Spindle and ESS
« Reply #6 on: April 14, 2015, 08:48:27 AM »
Have fitted an AC servo to a large spindle (380mm chuck). 
Dan

Hello Dan,
 Just curious ... what is the brand and kw rating of this motor/drive combination ?
Are you using an external braking resistor or shunt ?
I would think that the drive would trip from the back feed before it would strip the belts.
Must be a real power house.
 
Thanks Dan,
Russ
 :)

Offline Dan13

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Re: AC Servo Spindle and ESS
« Reply #7 on: April 14, 2015, 10:09:39 AM »
Jeff, it is the possibility of mechanical damage to the machine by hitting a wrong button in Mach which frightens me. I want my machine to be fool proof. Also, I still keep getting the "SmoothStepper ran out of data" message every now and then, and I am not sure about this, but I think it would also cause that sudden stop. Again, not sure about this one as I've just fitted the large chuck and with small one it really never made a difference how it stopped so don't recall.

Russ, it is a 2kW Delta servo. Don't have an external resistor. It has a 6:1 reduction transmission to the spindle, so the motor doesn't experience the full inertia of the load. Still easily tears an HTD-5M 15mm wide belt not even tripping an error.

Dan

Offline Jeff_Birt

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Re: AC Servo Spindle and ESS
« Reply #8 on: April 14, 2015, 10:29:29 AM »
Make sure you are using the latest ESS plug-in and a Mach version higher than 3.043.058. There was an issue with how previous versions of Mach filled the motion buffer that could cause the 'ran out of data' problem.

If you want to avoid the possibility of a user hitting Stop and causing a problem then write your own macro for the Stop button, it could do a feed hold and wait till the machine stopped moving and then issue the stop. You will have a similar problem though if the user hits EStop so you might need a brake on the spindle to stop if safely in an emergency.
Happy machining , Jeff Birt
 

Offline ger21

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Re: AC Servo Spindle and ESS
« Reply #9 on: April 14, 2015, 10:52:39 AM »
Correct me if I'm wrong, but feedhold does not stop the spindle, so it won't help him.
Gerry

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