Re: Digital DC Variable Speed Drive for spindle control

Mr.Mina F.,
I hope the mentioned encoder is mounted on the machine's spindle
either directly or with 1:1 timing pully .This encoder is exclusively
used for measuring speed/position feedback of spindle by the CNC.It
should not be used to control the drive since a gearbox is in between.
If you want to contol motor with encoder it should be mounted on the
motor itself.
However this spindle encoder feedback to CNC is must for cycles like
threadcutting,constant suface speed etc.
I do not know the spec of mach2.check with them whether spindle
encoder feedback is required or not.

My suggestion for dc drive use analog reference and tacho feedback.

Of course Mentor is a good drive.Be careful in selecting the drive.I
had a strange problem with menthor while setting up for analog speed
ref .Drive will not respond for +/-0.6v .It is about 6% for 10v.say
for 1500rpm base speed it is about 100rpm.
I wont suggest to use this drive for machine tool application.
I have used it about 6years back.I am not sure if at all they updated
software latter for min.speed deadband.Also I am not tried any other
type of speed reference.
Be sure to select a regenerative dc drive without deadband limitaion
and speed reference of your choice which Mach2 supports.
Hope above message helps you.
Regards
sivaraj

>
> At 05:55 AM 1/26/04, you wrote:
> >Hi Bryan,
> >
> >Thanks for the input I took a look at the Carotron site and I liked
> >what I saw, a couple of points I would like your opinion about:
> >- When you say the drive will accept frequency inputs as standard

do

> >you mean like step pulses from mach2?
> >- If so, which way would you go, step & Dir, or serial
> >communication?? I asked Art about mach2 supporting serial
> >communication, and he said mach2 can be configured to send serial
> >commands but not receive.
> >- In my lathe setup, I have a tacho attached to the motor, and an
> >encoder attached to the spindle (1024) PPR, and there is a 3 speed
> >gearbox between motor and spindle, which way to go for feed back,
> >tacho or encoder.
> >
> >I'm sorry I'm asking all sort of questions, as I'm doing this for
> >the first time.
> >
> >Mina F.
> >
> >
> >--- In CAD_CAM_EDM_DRO@yahoogroups.com, fiteboss@y... wrote:
> > > Control Techniques makes good drives, if (IMO) a little bit
> >overpriced.
> > >
> > > For DC drives, I really, Really like Carotron. Good pricing,

great

> > > technical support. They aren't as pretty as some others, but

they

> >get the
> > > job done, day in and day out. Mike Jenkins and his crew make an
> >excellent
> > > product. I've got quite a few installed in some severe

industrial

> > > environments, and I've *never* had a failure. Amazing.
> > >
> > > The ElitePro drive will accept frequency inputs as standard, as
> >well as
> > > 1024PPR quadrature feedback. Configure one of your 7 digital
> >inputs as
> > > direction. Or use the supplied RS232 or 422 communications

ports.

> >Speed
> > > regulation with encoder feedback is +0.01%
> > > http://www.carotron.com
> > >
> > > BTW, DC drives are not inverters.
> > >
> > > Bryan Moody
> > > Not affiliated with Carotron!
> > > Just a very satisfied systems integrator.
> > >
> > >
> > >
> > >
> > > At 05:51 PM 1/24/04, you wrote:
> > > >Gentlemen,
> > > >
> > > >I'm in the process of changing the old Fanuc controller of a
> >medium size bed
> > > >lathe to a new control using mach2 and Geckos.
> > > >I already setup my Z&X axis, and they are working fine, now I'm
> >getting to
> > > >the part of spindle speed control, the spindle motor is a 11 Kw
> >BBC
> > > >DC motor, which came with its old speed controller which I'm
> >scrapping.
> > > >I'm thinking of buying a new digital DC variable speed drive
> >(inverter) for
> > > >the motor like the one in the URL below:
> > >
> > >http://www.controltechniques.co.uk/products/mentor_intro.

htm#Benefit

> >s
> > > > I know it's a bit expensive, but I'm planning to use the

lathe

> >for
> > > >production work, now I was wondering of the way to control the
> >speed drive
> > > >from mach2:
> > > >
> > > >- Can I send step & Dir pulses to the speed drive as it has
> >digital inputs.
> > > >- I have a 1024 PPR encoder attached to the spindle, do I send
> >the encoder
> > > >pulses to the speed controller for feed back.
> > > >- If so, can I rely on the speed controller to keep a constant
> >speed, for
> > > >threading operations, or do I have to take an index pulse to
> >mach2 to do
> > > >threading.
> > > >- I think mach2 does not support serial communication to speed
> >drives, am I
> > > >correct.
> > > >
> > > >- If non of the above is feasible, what other options do I have

to

> > > >communicate between mach2 and speed drives?
> > > >
> > > >Please advise,
> > > >
> > > >Mina F.
> > > >
> > > >P.S. I apologize for multiple group posting.
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >Addresses:
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> > > >davemucha@j... [Moderators]
> > > >URL to this group: http://groups.yahoo

com/group/CAD_CAM_EDM_DRO

> > > >
> > > >OFF Topic POSTS: General Machining
> > > >If you wish to post on unlimited OT subjects
> > > >goto: aol://5863:126/rec.crafts.metalworking or go thru
> >Google.com to
> > > >reach it if you have trouble.
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> > > >
> > > >http://groups.yahoo.com/group/jobshophomeshop I consider this
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> > > >sister site to the CCED group, as many of the same members are
> >there, for
> > > >OT subjects, that are not allowed on the CCED list.
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> >
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> >
> >OFF Topic POSTS: General Machining
> >If you wish to post on unlimited OT subjects
> >goto: aol://5863:126/rec.crafts.metalworking or go thru Google.

com to

> >reach it if you have trouble.
> >http://www.metalworking.com/news_servers.html
> >
> >http://groups.yahoo.com/group/jobshophomeshop I consider this to

be a

> >sister site to the CCED group, as many of the same members are

there, for

> >OT subjects, that are not allowed on the CCED list.
> >
> >NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING
> >THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS.....

...

> >bill
> >List Mom
> >List Owner
> >
> >
> >
> >Yahoo! Groups Links
> >
> >To visit your group on the web, go to:
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> >
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> >
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