Re: Electronic Lead Screw & Power Cross Feed | Poor Man's CNC ?

I've done machining for several years, but I'm new to CNC. I'm an
electronics engineer, so an electronic approach to gearing - rather
than mechanical gears - appeals. This PLL (Phase Lock Loop) method is
well-known in electronics.

Maybe electronic gearing could be called the "Poor Man's CNC". I'm
less interested in full programmable CNC right now than I am in
correcting some deficiencies in the SIEG C6B lathe I just bought. The
C6B has variable spindle speed, but fixed saddle traverse - so feed
rate is either 0.1mm/rev or 0.2mm/rev and switching between the two is
awkward. There is no Quick Change Gear Box, so threading requires
manual gear substitutions. There is no Power Cross Feed, and there is
no taper attachment. Seems to me PLL control of the lead screw, as
described in this article, with the enhancement of microprocessor
control of speed ratios, could give practically unlimited threading
and traverse speeds. Power cross feed could also be arranged by this
method. If Power Cross feed linked to lead screw speed, then this is
effectively an electronic taper attachment. Several tricks short of
full CNC could be microprocessor-controlled.

Am I missing something ?

I'm new at this. Could someone give me a head start on the kind of
stepper (?) motors I should be looking at, encoding wheels, and
microprocessor/computer control ? Someone who owns a SIEG C6 or
Grizzly G0516 might also be interested or could supply conversion
information.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, juan gelt <juangelt@y...> wrote:
>
> i will say that the circuit is primo basis for a
> tach/speed controller. he has 40 holes on his spindle
> sensor disk that he was gonna up to 120.
> we know (i'm still amazed!) that you can do threading
> with turboCNC and a single index point on spindle.
> his circuit didn't have indexing, nor require it to
> make 2 motors run in synch. the circuit deserves a
> star for precisely comprehending and solving a
> problem- but i'd say, once you have tachometry, speed
> control and indexing, you've got all there is to get.
> then it's just a matter of resolution and how fast you
> can do whatever you want with it.
>
>
> --- turbulatordude <dave_mucha@y...> wrote:
> > juan gelt <juangelt@y...> wrote:
> > >i believe the system will work with some limits of
> > > accuracy. however, i also have a question on the
> > > actual utility of it. if you are already CNC and
> > > have a spindle encoder, you have a much more elegant
> > > route to all the control, no?
> > >
> > Congratulations on being the first to accress this for it's
> > technical merits ! (I was geting to cut this thread.)
> >
> >
> > I have an old SB lathe with manual change gears.
> > I was thinking something like this would be a way to
> > just add variable speed to the spindle and also add electronic
> > thread cutting.
> > I didn't read thru the article with any accuracy,
> > just briefly and I did not see if the unit has a single alignment
> > point per revolution.
> > What actual value would this be to a home shop ?
> > And, is it more effort than adding CNC ?
> > Dave