Re: [CAD_CAM_EDM_DRO] Re: cnc lathe - threading - alternitivemethod?????

Hi Chris

I see your point. The question is-- can this be done with a PC and any of
the common software packages? Or maybe I should use the big Kollmorgen
servo motor and amp that I have for the spindle drive on the lathe I am
retrofitting.

Bob

----- Original Message -----
From: "Christopher Williams" <chris@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, March 12, 2005 4:16 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: cnc lathe - threading -
alternitivemethod?????


>
> Hi
>
> john, I agree you can cut theads with single pulse however you are very
limited with respect to feed and tool load. Therefore cycle times are
extended greatly due to only being able to take small cuts. This may not
matter for a hobbyist, however for a job shop this is not acceptable.
>
> Bob, to elaborate....the control system monitors the spindle speed and
adjusts the cut feed to maintain lead. We control feed as this can always
be controlled to higher precision than the spindle. Generally a spindle is
controlled with an 8 or 10 bit dac control signal driving an inverter.
Theredoer at best we have 1024 control inputs. Any motion controller worth
its salt will have a minimum of 65000:1 velocity control range. By
mearsueing the spindle speed to a high precision we can make fine
adjustments to cut speed therefore we are able to cut with heavy tool load.
>
> Chris
>
> -----Original Message-----
> From: "John Guenther" <j.guenther@...>
> Date: Sat, 12 Mar 2005 18:17:54
> To:<CAD_CAM_EDM_DRO@yahoogroups.com>
> Subject: RE: [CAD_CAM_EDM_DRO] Re: cnc lathe - threading - alternitive
> method?????
>
>
> TurboCNC uses a single pulse per rev for threading on a lathe. Mach2 or
> Mach3 uses either a single pulse per rev or a single index pulse and
> multiple pulses to sync the spindle speed. I have used Mach3 with a
single
> pulse per rev sensor to cut threads and it works great. This is not
really
> as complicated as everyone thinks it should be. It only really takes a
> single pulse per rev to cut accurate threads on a CNC lathe. IMHO you
> should get single pulse per rev threading working first and then determine
> if there is any benefit to multiple pulse per rev setups. I believe that
> Mach3 is limited to 24 pulses per rev maximum.
>
> John Guenther
> 'Ye Olde Pen Maker'
> Sterling, Virginia
>
>
> -----Original Message-----
> From: Bob Muse [mailto:mtebob1@...]
> Sent: Saturday, March 12, 2005 17:05
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] Re: cnc lathe - threading - alternitive
> method?????
>
>
>
> Hi Chris
>
> This is what I have been thinking it would take to cut accurite threads.
Do
> you know of any CNC controller programs that have this capability. The
> velocity loop for the spindle could be a function of the spindle drive
could
> it not?
>
> Bob
> ----- Original Message -----
> From: "chrisw0567" <chris@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Saturday, March 12, 2005 12:47 PM
> Subject: [CAD_CAM_EDM_DRO] Re: cnc lathe - threading - alternitive
> method?????
>
>
> >
> >
> >
> > hi,
> > to thread cut with any degree of accuracy you will require a single
> > pulse per rev input, and a 'n' pulses per rev input.
> >
> > the single pulse synchronises the start of cut.
> >
> > the 'n' pulses per rev provides input to a phase lock loop to
> > synchronise rotational velocity of the spindle with tip velocity of
> > the cutter. should this be ignored then pitch errors will occur when
> > the load on the spindle changes due to applied cutting forces.
> >
> > to acheive repeatability both inputs must be debounced.
> >
> > chrisw
> >
> >
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, Russ Waters
> > <mycncworld@y...> wrote:
> > > Hi to the group..... I need to pick your brain on this one!
> > >
> > > I would like to come up with a alternitive method of threading
> > with a cnc lathe,,,,, not using a feedback system with conjuntion of
> > the G33 code, but would it be possible to cordinate the spindle
> > speed with the feedrate of the z axis to do threading? I think it
> > could be done, has anyone tried this, or have a theory on how it
> > could be done????
> > >
> > > Russ
> > >
> > >
> > >
> > >
> > > ---------------------------------
> > > Do you Yahoo!?
> > > Yahoo! Search presents - Jib Jab's 'Second Term'
> > >
> > > [Non-text portions of this message have been removed]
> >
> >
> >
> >
> >
> >
> >
> >
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> http://www.metalworking.com/news_servers.html
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> 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........
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> 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.
> 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........
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> Kind Regards,
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> Chris Williams
>
> Let your email find you with BlackBerry from Vodafone
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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........
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