Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: DMBGO on March 01, 2011, 03:19:28 AM

Title: Servo Motor question
Post by: DMBGO on March 01, 2011, 03:19:28 AM
Hi I am looking at buying a mill which is already a cnc mill, it had the option of a built in Chinese CNC controller, but I asked them to quote the mill with just the servos and drives.

The Servos are AC servos, and I am wondering if there would be any difficulty interfacing them with Mach3.
Here is a link to the manual for the servo drives

http://www.gskcnc.com/Support/DA98A_ACDriver.pdf

I have had a lot of experience in the past with steppers, but servos are a whole new ball game to me.

Thanks
Dave
Title: Re: Servo Motor question
Post by: Hood on March 01, 2011, 03:42:24 AM
They will work fine with Mach but you may need to make up a line driver to change the single ended Step/Dir signals into differential signals. Some drives can accept single ended but I would recommend you use the differential  even if they can. It is easy enough to make up a line driver or you can buy them.
Hood
Title: Re: Servo Motor question
Post by: Hood on March 01, 2011, 04:14:52 AM
Just looked through the manual and they can accept single ended Step/Dir signals but as said best use the differential and the manual also says that.
Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 01, 2011, 04:40:21 AM
Thanks for that Hood, It's been a while! Sorry for being lazy and asking, I should have done my homework, but I needed to get back to the guy quickly.

Thanks again

Dave
Title: Re: Servo Motor question
Post by: Hood on March 01, 2011, 04:55:08 AM
No problem, One thing however will be  you will either have to use electronic gearing in the drive (I would think it has that) or use something like the SmoothStepper that can pulse a lot faster and cleaner than the PP.
Hood

Edit, just checked and it does have electronic gearing if you choose to go that route, personally I dont like it but others seem to find it ok.
Title: Re: Servo Motor question
Post by: DMBGO on March 01, 2011, 05:55:10 AM
I intend to use the smoothstepper with it, here's the machine btw

I'm also looking at the VM760

Any comments would be appreciated


Cheers
Dave

Title: Re: Servo Motor question
Post by: Hood on March 01, 2011, 06:31:51 AM
No contest for me, it would be the VM760, next choice would be the bedmill and last would be the turret/knee.

One thing I would say is the quill dia on the knee mill is too small to get the benefits that a 40 taper gives, the bedmill is better in that respect but the swivelling head would still put me off.

Suppose it depends on the type of work you will be doing. Big long stuff may be a PITA on a fully enclosed machine, then again removing of tin work likely wouldnt be too much of a problem if it was needed.
Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 01, 2011, 04:15:57 PM
The VM760 is what I am leaning towards too, It is quite modular in that you can buy anything from the base machine without motors ATC etc upwards.
Title: Re: Servo Motor question
Post by: Hood on March 01, 2011, 04:58:54 PM
Sounds like it is a decent machine, what kind of price are you talking?
Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 01, 2011, 05:02:32 PM
Base machine FRAME   $12,992.00
BT40 spindle speed 10000rpm extra   $179.00
4. Armless(Genoa) type 10 tools ATC       $1,456.00
10. Spindle motor 7.5hp (10000rpm, inverter motor   $1,064.00
12. Inverter driver 7.5hp/220V (VFD055V23A-2/Delta   $1,064.00
15. X,Y,Z with brake AC servo motor 220V/1kw   $980.00
18. Oil mist lubrication pump   $448.00
23. Remote handwheel   $280.00
Fumigation fee   $100.00
24. Limit switches (3 pcs)   $252.00
25. Interlock switch for front door   $224.00
26. Air gun   $34.00
27. Coolant gun   $34.00
20. Heat exchanger for electrical box   $134.00
21. Electrical fan for electrical box (1pcs)   $22.00
Title: Re: Servo Motor question
Post by: DMBGO on March 01, 2011, 05:03:39 PM
This is to import the machine from Taiwan, so there will be another $3000.00 in freight and port charges etc.
Title: Re: Servo Motor question
Post by: Hood on March 01, 2011, 05:11:21 PM
Not too bad I suppose, I like the fumigation charge ;D
Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 01, 2011, 05:12:35 PM
Well there could be worms in the castings!!
Title: Re: Servo Motor question
Post by: Hood on March 01, 2011, 05:16:17 PM
 ;D
Title: Re: Servo Motor question
Post by: DMBGO on March 11, 2011, 01:59:09 AM
I have pretty well decided to go with the VM760 machine frame below. I wont be buying the servos vfd or spindle from the manufacturer, since I think I can do better elsewhere. They have been pretty good to deal with so far, they are happy to provide couplers and make the motor mounts etc to suit the servos and spindle motor that I choose.
Title: Re: Servo Motor question
Post by: Hood on March 11, 2011, 03:19:48 AM
Sounds like a great place to deal with, keep us updated as things progress
Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 11, 2011, 03:30:36 AM
Hi again Hood et al; I have attached some specs for ADTECH servos, I don't know much about the manufacturer, but they seem quite price competitive. I was wondering if you could let me know your thoughts as to what you would select for the VM760. I am thinking of these:
ACH-13100CC Servo motor,1000W,2500RPM,4NM,4A
or
ACH-13100CC Servo motor,1000W,2500RPM,4NM,4A(Withbrake)
With this driver
QS6AA030M Servo Driver single phase or three phase 220V

Is 2500rpm fast enough? the servo will be direct coupled to the ballscrew

BTW Hood, I saw your latest post on the SS forum, I saw exactly those symptoms this arvo :)

Cheers

Dave
Title: Re: Servo Motor question
Post by: Hood on March 11, 2011, 04:19:11 AM
These colours are hard for me to read LOL
What confuses me is the motor specs say 4Nm cont torque but the graph suggests 10Nm cont.

2500RPM direct coupled with 5mm pitch will give you 12500mm/min max rapid.

Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 11, 2011, 06:19:53 AM
I don't understand the torque graph at all I think they made it up. Or scr-wed it up!
Title: Re: Servo Motor question
Post by: Hood on March 11, 2011, 06:32:43 AM
The graph is  what I would expect from the motors I have on the lathe, they are 3000rpm  10Nm cont 30 peak and about 3Kw.

Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 17, 2011, 04:18:41 AM
Still haven't made a servo decision, I am thinking of running the machine on 240v single phase, which I think is doable with 1kw AC servos, but not with bigger ones. I could also use Gekko 320X drives, but it means a beefy DC supply, and probably different servos.

Please feel free to tell me what you would do.

The manufacturer recommends that I buy their sheetmetal guarding, but I am trying to get the machine from Tiawan to my shed for under $20,000.00 and the guarding is a a few grand  more.

I am trying to do this as cheaply as possible, but end up with a really good machine. If I can get this system running the way I want I may end up supplying a few of these systems

Any suggestions about the servos I should use based on the machine details below? I feel a bit lost here.

Cheers
Dave
Title: Re: Servo Motor question
Post by: Overloaded on March 17, 2011, 07:58:37 AM
Hi Dave,
  I scrounge and salvage most all of my components as I'm in it mostly for fun.
 But if I were to buy new, I would try these from Automation Direct.
http://www.automationdirect.com/static/specs/sureservomed.pdf
They have 1,2 and 3KW 230V systems and pretty decent prices. All cables and breakouts ready to go.
Iv'e used their small PLC's and VFD's and have had good service with both, great support also (the little I required).
Title: Re: Servo Motor question
Post by: DMBGO on March 17, 2011, 02:38:48 PM
Thanks Overloaded, I read through the PDF on the link you provided, it was nicely laid out and easy to understand, but unfortunately, the prices were a it high. I am in Australia and once I pay freight they would cost substantially more than the others I was looking at.

Cheers
Dave
Title: Re: Servo Motor question
Post by: Hood on March 17, 2011, 04:26:00 PM
As Russ said you can get up to about 3Kw on single phase, the Allen Bradley motors I have on the lathe are that size.

Geckos are for DC motors and I think you were looking at AC servos so they will be no use. If you do go with DC servos then be careful as a lot of places that are selling them are quoting the peak torque rather than continuous.

Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 17, 2011, 07:26:39 PM
Thanks Hood,
I hear what you are saying, but the biggest single phase servo drives I've seen are around the 1kw mark.

The ones that Russ mentioned are 240V, but once you get over 1kw they need a 3 phase input.

Not really sure why this seems to be the case, 5kw single phase VFDs  are readily available and you can draw 30 amps from a single phase 240V supply if needed which is 7kw.

If you take 25% off 7kw for inefficiency in the motors and drives and then convert the result to HP for no particular reason, other than the fact that we started life in imperial and then changed to metric, you should be able to get 7HP from single phase.
Do you estimate things in feet and mm? ie.. 2ft and about 15mm

 
Title: Re: Servo Motor question
Post by: Hood on March 17, 2011, 07:38:41 PM
Have a scout on eBay and see if you can pick up some Allen Bradley or Giddings and Lewis drives and motors. The ones to look for are Allen Bradley DSD or Giddings and Lewis DSA drives, they are the same. The ones I have on the lathe are DSD-030 which are 3Kw 240v Single phase.

No being an ex fisherman anything over a meter and I think in Fathoms ;D

Hood
Title: Re: Servo Motor question
Post by: Hood on March 17, 2011, 07:41:47 PM
Oh but check that they are not HV drives as they are 3 phase 440v.
The older drives, DDM/DSD may also be worth looking for, the biggest again for single phase is the 030 although the DDM-075 can be run single phase but it is derated from 7.5Kw to 3Kw if you do so.

Check with me before you buy any though as I will keep you straight as there are many variations of them.
Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 18, 2011, 06:52:38 PM
Well after a fair bit of research I am nearly back where I started servo wise. Please have a look at this and see what you think. If you think I'm making a mistake pls let me know :)

I've pretty well decided on the GSK 1kw AC servos and the GA98B controller. I will use non braked motors on the X and Y axis and a braked motor on the Z. The servos accept single or 3 phase 220v +- 10% so they should be fine with our single phase supply.

The GA98B servo drive accepts and I quote:
"Position mode(Position command mode: ① pulse + direction; ② CCW pulse/CW pulse; ③ A/B two phases orthogonal pulse) and External speed mode (Two external speed commands: ①-10V~+10V analog voltage command speed and direction; ② 0V~+10V analog voltage command speed of which the operation direction is selected by the input signal). "

max speed of the servos is 3000rpm with 2500rpm continuous, torque is 4nm cont 10nm max

The drive will accept pulses up to 1mhz in speed, has a 5000 lline encoder and apparently is accurate to 0.018 degrees of rotation, which should be rough enough. ;D
 
These are almost the same as the first ones I posted Hood, which were GSK GA98As
Just waiting on final pricing for the mill, then it's all go, or should I say it's all wait for factory wait for shipping then go.

Cheers
Dave
Title: Re: Servo Motor question
Post by: Hood on March 18, 2011, 07:00:36 PM
Specs sound good and the numbers seem to work out, I seem to recall the first motors mentioned seemed a bit dodgy on the numbers?
Drives too will be fine as pulse/direction is just another way of saying Step/Dir.
Encoders are quite high res, 2000 or 2500 being sort of normal but that wont cause an issue if you are planning on using something like the SmoothStepper.
Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 18, 2011, 07:27:43 PM
Those earlier motors with the dodgy specs were from adtech here are the brochures for the GSK motors and drive. I am a really big smoothstepper fan, since I sorted out the noise issues a few months ago the SmoothStepper has been a model of integrity. I am just about to buy another for the new mill. I was going to share a controller between the lathe and Mill, but I think that's being stingy.

Cheers
Dave
Title: Re: Servo Motor question
Post by: Hood on March 18, 2011, 07:43:11 PM
Think you better double check the input voltage reuirements, to me it would suggest its 3 phase 220v.
Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 18, 2011, 07:46:41 PM
No, it's Ok, I asked about that too, the top line is single phase, and the second line is 3 phase, so they will take either.
Thanks
Dave
Title: Re: Servo Motor question
Post by: DMBGO on March 18, 2011, 07:49:32 PM
Actually I'm thinking of buying what they call a variator from them as well anyway. Apparently it's a phase converter and it would come in handy from time to time.
I wasn't planning too do this, but I am keen to use the 10,000rpm spindle motor and drive that comes with the mill and that's 3 phase only

Cheers
Dave
Title: Re: Servo Motor question
Post by: Hood on March 18, 2011, 07:52:34 PM
Ok, thats good, I was thinking the top line was in Chinese and the one under was the Engrish version.
Reason I thought that was if you look at theChinese writing in the Main Power its different from that in the Control power, well the first part of the Chinese writing is.

Hood
Title: Re: Servo Motor question
Post by: Hood on March 18, 2011, 07:53:20 PM
Never heard of a variator, got any links?
Hood
Title: Re: Servo Motor question
Post by: Hood on March 18, 2011, 09:06:24 PM
I have just done a translation of the Chinese 三相 which appears in the Main Power section and it means 3 Phase like I was thinking, I would check again with the suppliers to make sure, but maybe I am being overly cautious ::)
Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 18, 2011, 09:35:52 PM
Ok, I'll check now thanks for going to the trouble Hood
Title: Re: Servo Motor question
Post by: DMBGO on March 19, 2011, 04:17:43 AM
here's what they said in the quote:
"2. DA98B-10/110SJT-MZ040D(A2Y2) AC SERVO UNIT (1.0KW、4Nm、2500rpm、5000pps incremental
encoder, 3-phase or single phase AC220V input, short shaft, with brake) for Z axis: 1 SET "

However the DA98B user manual says 240v single phase up to 0.8Kw and 3 phase 1 Kw and over.

I will have to re-clarify this with them, but it does look like the drive will accept either single or 3 phase, there are just some output power limits on single phase.

Thanks for bringing this to my attention

Cheers
Dave


Title: Re: Servo Motor question
Post by: DMBGO on March 26, 2011, 07:44:41 PM
Well a bit of time has gone by and I have made a decision about the VMC-760 machining centre. I decided not to go ahead at the last minute. The supplier was adamant that I use their 3 phase spindle, which would have necessitated buying what they called a variator. Unfortunately, despite numerous e-mails they were unable to give me any clear information as to what a variator was. I assume that it is a phase converter, but whether it's  mechanical or electronic I don't know. To this day I am perplexed. I think they just didn't understand my questions; I would say "I believe a variator is a type of phase converter, could you please tell me if it is a mechanical or solid state device" and they would say something like "The spindle need 3 phase power you need variator to operate it with single phase". We just kept going in circles until I gave up. Once I had given up they sent me this link in an attempt to resurrect the sale but they couldn't tell me what model the one they were quoting was.

http://www.shinhsing.com.tw/index.php?option=com_content&task=view&id=46&Itemid=45

In the end I lost confidence and decided it was too much money to spend, when I didn't really know what I was going to end up with and how expensive and time consuming it was going to be to sort out the inevitable problems. I probably should have just bought the basic machine frame and then sourced the remaining electrical components after it arrived, but by this stage I was worn down and was getting impatient.

One day I will go to Taiwan and China and have a look at the factories over there it should be fascinating.

Having put the import business to bed I turned around and ordered a convention knee mill from a local Melbourne supplier, since I had just sold my existing mill being sure that I was going ahead with the VMC-760.

The mill I have bought is a King Rich KR-V3000, which is set up already for CNC conversion with ground C5 ballscrews on the X and Y and precast brackets for the servos. I just need to supply and fit the motors, put a ballscrew on the quill and do the wiring.
There are a couple of conversion threads on CNCZone for this mill:
http://www.cnczone.com/forums/knee_vertical_mills/117112-conversion_king_rich_3000_a.html
http://www.cnczone.com/forums/knee_vertical_mills/105668-king_rich_krv-2000_knee_mill.html

I had already ordered the 1 kw servos from GSK, after they confirmed that their 1kw servo is fine on 240v single phase, GSK was a bit concerned that I may be under powering the mill, but the guys on CncZone who have converted these mills have used 400watt and 750watt motors in their conversions, so hopefully I will be Ok.

Since I had saved some money by not buying the machining centre I went ahead and ordered some more servos for the lathe as well. I found a single phase 2.5kw one with 2500rpm and a 5000line encoder and drive from Adtech that runs on single phase. I intend to put this on the spindle, and two 500watt servos for the X and Z drives, which should put the lost steps from my steppers to bed.

The mill should arrive in the next week or so so I think I might document the conversion on CncZone, since it seems to be the in thing.

Cheers
Dave

Title: Re: Servo Motor question
Post by: Hood on March 27, 2011, 03:20:36 AM
Sad to hear that Dave, a bed mill would have been my choice but suppose it depends what kind of work you will be doing and whether the Z axis travel will be important. Add to that a toolchanger is much easier to add to a bedmill than a knee mill then ....... but as said all depends on whet you will be using it for.

1Kw servos should be fine as long as they are what they say they are, worst case you would have to gear which would impact on the rapids but would still allow reasonable rapids I think (depends RPM of motor and pitch of screws).

What kind of money are they asking for the 2.5Kw motors/drives, if you dont mind me asking. I have found a place in the UK thats selling Chinese drives/motors but dont know the prices for the bigger stuff, they have .75Kw motor/drive/cables for £650 which sounds reasonable, but I imagine that price would ramp up quickly with the Kw.

Please document here as well in the Show and Tell section, even if its just a copy and paste of what you put on the zone.
Hood
Title: Re: Servo Motor question
Post by: DMBGO on December 08, 2011, 05:18:09 PM
Well a whole .lot of time has gone by now! I was unfortunate enough to have a very serious car accident on the 31st of march this year, and have spent the last 6 months in rehab, that is after I got out of emergency and then intensive care. The ambulance drivers said it was the worst accident they had seen where the driver lived. Apparently I was unconscious for 6 weeks. Consequently all I had time to do was take delivery of the mill and that's it.
I suffered a brain injury at the same time, so now even though I went through a lot of planning before ordering the mill, I now don't remember anything much.

Oh well looks like it's time to start again.

Cheers

Dave
Title: Re: Servo Motor question
Post by: Hood on December 09, 2011, 02:53:08 AM
Good to hear you are on the mend.
Hood
Title: Re: Servo Motor question
Post by: DMBGO on December 22, 2011, 10:08:46 PM
I can't remember why I chose the knee mill now, and I don't know why I ordered what from GSK and from Adtech. I appear to have a set of servos and drivers for the lathe from Adtech, as well as most things needed to CNC the mill from GSK including an off the shelf CNC controller! The CNC controller is a GSK 980MDa. I don't know why I bought a dedicated CNC controller, but I am hoping that I can use it to compare mach3 to the "off the shelf" product and depending on the results, keep it, or resell it.
Both GSK and Adtech were very good while I was in hospital and ensured that their stuff found its way into my shed. Even to the extent of calling in favours from other people in this country to pay for things like GST on my behalf, for which I am extremely grateful.

Having forgotten why I purchased what I did, I thought I would start with the lathe, since it has already had a CNC conversion, just using steppers and Gecko drives instead of servos and their propriety drives. So it should be an exercise in memory refreshing to replace the existing steppers for servos. I suspect that I planned to replace the 3phase main motor and VFD with a servo as well (at least I have 3 x servos from Adtech).

I thought I might start by getting one of the Lathe servos running, perhaps on the bench, and getting it under computer control with mach3 and my smoothstepper.

At this point any advice would be gratefully appreciated, as I  think I said earlier in this thread this is my first foray into the world of servos. Add to that my memory loss from the accident and I anticipate that this will be tough, but a good mental exercise.

Have a great Xmas BTW.
Title: Re: Servo Motor question
Post by: Shurupand on May 16, 2012, 03:26:55 AM
A very interesting story. However, I understand very little English.
So you built your milling machine
Title: Re: Servo Motor question
Post by: DMBGO on October 22, 2013, 05:53:09 PM
Hi Shurupand,
I am still building it after all this time. The accident was worse than I thought initially and I now have severe problems with my short term memory. The new Mill has been sitting in my shed unused for over 2 years.