Hello Guest it is January 22, 2020, 08:21:54 PM

Author Topic: Galil vs Vital  (Read 659 times)

0 Members and 1 Guest are viewing this topic.

Re: Galil vs Vital
« Reply #10 on: November 04, 2019, 11:11:29 AM »
My machine is running on AC servos using Step/Dir (actually quadrature) signals from an Ethernet SmoothStepper (ESS) from Warp9TD and Mach4. I am extremely happy with the system. I think you will find AC servos to offer higher performance compared to DC systems.

I think JoeAverage has done an excellent job describing the system, so I won't get into that, but one thing to consider is selecting a servo drive which has dual loop control using load feedback. In this case, both the motor encoder AND the glass scales would be wired into the servo drive which handles the position, velocity, and current loops entirely on its own. You only need to give it a command (Step/Dir for example) and it handles everything else.

If you use an ESS, you can easily bring the encoder outputs from the drive back to Mach 4 for display purposes. As far as Mach 4 is concerned, it is driving an open loop stepper motor, but you really have full closed loop control at the drive.

Not every servo drive can do this, but I know the new Kinetix 5100 from AB has this feature as well as select drives from Delta, Omron, Baldor, and likely most big name suppliers. Give them a call and ask what their offering is for standalone drives with dual loop load feedback.

https://ab.rockwellautomation.com/Motion-Control/Servo-Drives/Kinetix-Indexing-and-Stand-Alone/Kinetix-5100

https://www.deltaww.com/Products/CategoryListT1.aspx?CID=060201&PID=23&hl=en-US&Name=ASDA-A2+Series


If I had a nicer machine, this would be the route I would take!
Re: Galil vs Vital
« Reply #11 on: November 04, 2019, 03:20:33 PM »
Hi,
yes the Delta A2 series have dual reading encoder inputs, you can have the best of both worlds, a 1,280,000 count per rev rotary encoder AND
your existing linear scales. The A2 series commands a premium of several hundred dollars over the 'standard' B2 series.

As I have posted previously, modern AC servos and their drives just leave all the old DC servos in the dust!!!

Craig

My wife left with my best friend...
     and I miss him!
Re: Galil vs Vital
« Reply #12 on: November 06, 2019, 12:01:19 AM »
Hi,
just saw this:

https://www.ebay.com/itm/ECMA-C10807RS-ASD-A2-0721-L-DELTA-A2-750w-3000rpm-AC-servo-motor-driver-kit/172283162086?hash=item281ce06de6:g:TkYAAOSwIsFcpYRy

It would appear that the A2 series is NOT that much dearer than the B2 series. I wish I had known that a month or so
ago!

Craig
My wife left with my best friend...
     and I miss him!
Re: Galil vs Vital
« Reply #13 on: November 06, 2019, 11:11:25 AM »
Those are some solid prices for a really good drive!  I see the drives selling used for $150-250 on ebay.
Re: Galil vs Vital
« Reply #14 on: November 06, 2019, 01:07:55 PM »
Hi Tony,
with this new capability this would be my recommendation for your original question:

Replace your existing DC servos with 750W Delta A2 series servos and drives. They would operate dual loop, that is
with their own built-in encoder AND your existing linear scales.

The cost would be:
3 x Delta 750W A2 servo/servo drive            $1524.75
ESS                                                             $180.00
MB03 Breakout Board                                   $180.00

Total                                                           $1884.75  Plus shipping and taxes if any.

That solution would be cheaper than a new Galill but rather more than a Hicon (with analogue activations) but have the advantage
of crispy new servos.......I can promise you they will blow your socks off!

Craig
My wife left with my best friend...
     and I miss him!
Re: Galil vs Vital
« Reply #15 on: November 06, 2019, 01:15:02 PM »
Hi Tony,
should have added the price of a drive programming cable. I bought a USB to IEEE1390 for $62 including shipping.
Alternatively, and a bit cheaper, RS323 to IEEE1390 are about $35.

I regard a programming cable as all but essential if you are going to use late spec Delta servos.

Craig
My wife left with my best friend...
     and I miss him!
Re: Galil vs Vital
« Reply #16 on: November 06, 2019, 01:59:06 PM »
Craig,

I revisited your responses from the beginning and I note that you mentioned the Gecko 320X.  I just had a look at those and they appear to be suitable.  OK maybe not state of the art but my needs are not production nor customer based.  Purely for making some parts for my own classic racing motorcycles.  I guess that the Gecko performance is short of what the Deltas would produce but otherwise would they do what I need if I kept the original motors?  I guess that I would still need the ESS and breakout boards?
I had previously associated Geckos with stepper motors and so I never considered them earlier.
With any of these options do I feed other inputs like an MPG in through the breakout boards or.....?
Re: Galil vs Vital
« Reply #17 on: November 06, 2019, 02:42:29 PM »
Hi Tony,

Quote
I revisited your responses from the beginning and I note that you mentioned the Gecko 320X.  I just had a look at those and they appear to be suitable.

Sorry to burst your bubble but I don't think they are suitable. The Geckos  G320 are expecting a rotary encoder that must be directly and positively linked to the servo motor
shaft. What you have is a linear scale that is not absolutely and directly linked. I suspect that that flexure/backlash/lost motion between the axis (as measured by the
linear scale) and the servo motor shaft would render the G320 feedback loop unstable.


Craig
My wife left with my best friend...
     and I miss him!
Re: Galil vs Vital
« Reply #18 on: November 07, 2019, 10:56:24 AM »
Or install an encoder on the motor shaft if it doesn't already have one. AMCI and US Digital offer low cost low profile encoder options. The glass scales wouldn't be used in this case.
Re: Galil vs Vital
« Reply #19 on: November 07, 2019, 12:07:43 PM »
Yes I was thinking about that also.  If the tachos were not used then there would be plenty of room.
The motors and ballscrews are connected by a toothed belt, would it be better to put encoders on the motors or ball screws?  On the motors would be the easiest.