Re: Electronic Lead Screw | Poor Man''s CNC ? - mini-lathe
Posted by
John Stevenson
on 2005-12-04 05:32:14 UTC
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Vaso" <borpe2001@y...> wrote:I own a C6 variable but I bought this as a CNC conversion machine from day one.
> >
> > 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.
> >
I had thought about electronic threading and did some work into this but soon realised it took more work to get one axis moving under power that to do a full conversion.
The reason for this is many people have trod this path before and you take advantage of that situation.
The two main contendors for a controller are TurboCNC and Mach3, as different as chalk and cheese but both work in their various ways.
I aim to use Mach3 as with this program and with an add on ModIO board I will be able to still run as a manual machine with two electronic handwheels MPG's.
Top slide will be scrapped to make way for a rigid toolpost and later for a tool changer. Leadscrew and cross slide screw will be replaced by ball screws.
All the leadscrew gearing will be scrapped. A size 23 stepper at 210 oz in and 2:1 reduction will drive the X, 312 oz in type 23 stepper at 2:1 will drive the Z.
Power supply will be 65 volts Dc driving into two Chinese drives similar to a Gecko [ 80volt 7.5 Amp microstepping ]
Threading encoder will be a one pulse per rev opto switch and the machine will be fitted with 4 limit switches.
Opto board by http://www.cnc4pc.com and ModIO board for the MPG's by Peter Honman.
The drive has already been modified by fitting a two step polyvee belt drive to both increase spindle speeds and lower them in the two ranges with more torque in the lower range.
John S.
This e-mail was scanned for viruses using BitDefender