Re: Bridgeport retrofit servo questions 1:1 ratio

Yeah...more like $110 or so each on Ebay with discontinued new old
stock encoders. I don't really like the Ameteks for the BP
conversion. There is little data on them (some people use them as
windmill generators with mixed results)...and I bet that I have 2
similar ones in my BP tape drive, but they are NEMA 23 size. I think
that they are just too small for this machine to get the kind of
performance that I want out of it.

I'm going to go w/ the 2HP ones that I mentioned. They need 15A and
that figure alone tells me that they have some umph to them. The
Ameteks look like they might be better suited on my Router or Plasma
rig where cutting force is much less than the BP. Plasma for
sure...router, maybe.

-Brady


--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers <rogersmach@y...>
wrote:

> Three Ameteks would work probably. They are like $20 each if you

look hard enough. I think "Silicon salvage" has them on Ebay for
about that price, they did anyway. 5/8" shaft, 40 volts DC and like
1200 RPM if I remember correctly. And I just learned today on here
those can be ran at higher voltage through the Gecko. Just put an
encoder on them. It would be worth a try. I know one guy was selling
a 2 axis retrofit package for series1 BP's and that was the motors he
offered. They sell them all the time on Ebay with encoders for like
$100 ea.

>
> Ron
>
> braidmeister <braidmeister@y...> wrote:
>
>
> Ron,
> FYI, this is a BOSS machine. It was designed 100% for CNC with no
> other purpose ~ according to Bridgeport specs. It is not a manual
> mill converted to CNC.
>
> The knee is manual to accomodate variations in material height. The
> knee is not driven by the stepper. Only the quill/spindle shaft

moves

> in Z ~ quite a big difference in mass to move. The Z motor moves

just

> as easily as the X & Y ones, by hand turning a small 2.5" pulley

with

> my fingers.
>
> To those of you that are going to try moving the pulleys by hand,

do

> so with the controls/power OFF. 1st reason being that quick

movement

> can acutally turn the motor into a generator and smoke the
> driver...2nd and more importantly, a stepper has max holding torque
> at zero RPM...once you break the magnetic lock on the motor and

your

> fingers are in there...It WILL BITE YOU!!! Don't ask how I know!
> (Actually I knew this before hand in theory...but forgot) :)
>
> -Brady
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers
> wrote:
> >
> >
> > braidmeister
> wrote:
> >
> >
> > Ron,
> > I get what you are saying about 4th gear. I will try them 1:1

1st,

> > and if need be, I will reduce to a 2:1 or better ratio. No sense

in

> > spending the $ for pulleys and belts if it is not necessary.
> >
> > In all actuality, yes it is a 3100 RPM servo @ 130 vdc. Since I

am

> > planning on running them @ 75v max, then I will have a max RPM of
> > only about 1700. That brings the rapids down quite a bit. I doubt
> > that I will need the full 2HP of the motor since I can easily

move

> > the axes by hand turning the pulley.
> >
> > /// We discussed the power input at the screw just recently. A
> handcrank has about a 6" diameter path of travel, 3" radius. A

crank

> revolved 1 rev constitutes about 18.84 " of circular travel. This
> circular distance produces .200" inches of linear table travel (5
> tpi). Or 94.2:1 ratio. Each pound of force presented to the handle

of

> the crank equals 94.2 lbs of linear force. 10 lbs , roughly 1/2

ton.

> So, servo torque is really not that big of an issue. The little
> Ameteks will work for X and Y. Except in the case of Z driving the
> knee. Different situation altogether. About 800lbs going up, coming
> down is no problem. And then add a large bit hogging out

material...Z

> is the biggest headache by far. Put the biggest motor you can power
> on it. I only get 50 ipm out of Z with a 40 in-lb motor. ///
> >
> > bounce things back and forth on...to me it is 100% American ~
> Better,
> > cheaper, faster
> >
> > /// As I told an engineer recently about those attributes, pick
> two, ya can't have all three.///Ron
> >
> > & elimination of the middleman for those of us who
> > know how to turn a wrench.
> >
> > -Brady
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers
> > wrote:
> > >
> > >
> > > braidmeister
> > wrote:
> > >
> > >
> > > No I was the one throwing planes!!
> > >
> > > Yes, that's the motor in question. It seems to me that it would
> be
> > an
> > > ideal fit for the BP. I am hoping that I can get away with 1:1
> and
> > a
> > > decent encoder.
> > >
> > > /// Trying to run a 3100 rpm servo 1:1 to a 5 tpi ballscrew

will

> > produce rapids of 620 ipm. One needs from 2:1 to 3:1 reduction on
> all
> > 3 axies using servos (driving the knee, its half the increment of

X

> > and Y per rev.). Simply increasing encoder count to attain
> resolution
> > is not practical. An E5S-200 encoder, Gecko 320's and Mach2 work
> > perfectly together using the above ratios. 1:1 ratio is like
> driving
> > a car around in 4th gear. Servos operate best at 80% of their

rated

> > RPM. I just ordered a set of pullies from mcmaster carr three L
> (.375
> > pitch)series 30 tooth (3.5" dia) and three L series 12 tooth (

1.4"

> > dia) for a 2.5:1 setup/// Ron
> > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> >
> >
> >
> >
> >
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