Re: Bridgeport servo motors

Scott,
Unfortunately...It is correct...they ARE CCW...#$^%^(*()&$!!!!

I just called them and the tech opened up the motor and looked at the
brushes. He said that it did sound different running it forwards or
backwards...BUT the brushes were angled...and there is no easy way to
get them timed for both directs.

WHAT A HUGE DISAPPOINTMENT!!!

So now...back to freakin' square 1. I would be interested in other
types of motors than these or the Ameteks (too slow). Anybody got a
source for 3 that will work at a decent price? (Decent meaning better
than $400 ea)

SO here's a question for you people: Since Surplus Center advertised
the motors as bi-directional, who pays for the shipping up and back?
Why should I have to pay shipping on something that was falsely
advertised?

-Brady

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Polaraligned"
<polaraligned@o...> wrote:

>
> These motors were custom made for HP. They are brand new. They
> even came in the brand new packaging. I guess in your situation
> you are looking for a set up that will "bolt in" for your Boss.
> I know I can't run these 1:1, but I am just trying to figure out
> what ratio I need. I'd like to do the conversion right the first
> time. I am very interested to see how your motors work out.
> I did check them out a couple of weeks ago.
>
> Good luck,
> Scott
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "braidmeister"
> <braidmeister@y...> wrote:
> >
> > Scott,
> > The Ametek's look very appealing initially, but I don't like them

for

> > a Bridgeport for several reasons:
> >
> > 1. Many of the Ametek ones don't have a 2" or longer shaft on

them.

> > You need 2" or better if you want to bolt right up to a BOSS

factory

> > belt drive.
> >
> > 2. I don't think that they have enough power to run 1:1, and the
> > highest RPM I have seen them rated to is about 2000 RPM or so. So

if

> > you did gear them down to 2:1, you might see a max rapid rate of

150

> > if they can pull the load.
> >
> > 3. They are used...not sure the condition of them, but they were
> > designed for a reel to reel tape drive...
> >
> > I don't have any direct experience with these motors and

initially

> > was looking at them. Surplus center sells a few variations of

them.

> > The 36v model has a 5/8" X 2" shaft that will bolt right up to

the

> > BPs drive belts.
> >
> > I just bought 3 of these puppies:
> > http://www.surpluscenter.com/item.asp?

UID=2005020410354708&item=10-

> > 1802&catname=electric
> >
> > I chose them because they will definately have enough power for

the

> > retrofit running 1:1. I don't plan on running them full voltage,

so

> > my rapids will be a little slower...but still capable of over 400

IPM

> > in theory. I'm going to shoot for the 150-200 IPM range and be

happy

> > with that.
> >
> > The reasons I chose them are they are cheap @ $80 ea, they have 2
> > 5/8" shafts that are 2.5" long, and they are 9.125" long at the

body

> > so they will fit between the Y axis and the knee. I will have to
> > shorten the shaft on the Y...but it sure beats trying to EXTEND a
> > shaft, which is the case with the treadmill motors. So, aside

from

> > shortening the rear shaft and making some type of mounting/face
> > plate, these are a bolt-in deal. I really didn't want to fool

around

> > with extending shafts, drilling shafts for encoders or coming up

with

> > some type of external belt-drive because the motor was too long

etc.

> > Belt drives are not cheap...
> >
> > I haven't decided on a servo drive yet. I am leaning towards the
> > Rutex though because it has more features that the

Gecko...although

> > wiring is a bit more complicated.
> >
> > Hope that helps,
> > -Brady
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Polaraligned"
> > <polaraligned@o...> wrote:
> > >
> > >
> > > There has to be a difference between a new servo motor at $800+

and

> > a
> > > brand (not surplus) treadmill motor at $100+.
> > > I have servo motors that I paid, what some would say "dearly"

for,

> > > from a dealer on e-bay. He has sold hundreds of these surplus
> > motors
> > > and has excellent feedback. He states that as many as half

have

> > been
> > > used sucessfully on Bridgeport retrofits. Of course, he has an
> > > interest in selling motors so....
> > >
> > > Here are the motor specs:
> > >
> > > Torque constant: 44oz-in/amp
> > > Voltage constant: 32.5v/1000 rmp
> > > Peak torque: 600 oz-in, or 37.5 in-lb
> > > Nominal voltage: 40vdc
> > > Maximum voltage: 60vdc
> > > Demagnitization current: >20amps
> > > Terminal resistance 2.60 ohm
> > > Max rpm at 50vdc is about 1200 rpm
> > > No-load current <.51 amp
> > > armature inertia .09oz-in-sec^2
> > > 4 bolt holes in face for easy mounting.
> > >
> > > They came with 1000 CPR Renco encoders pre-mounted. I may move
> > > the encoder to the leadscrew though. The seller states that
> > > these are the largest servo's that a Gecko will drive. The

motor

> > > also has a heavy duty front ball bearing. At $150 per motor

with

> > > encoder installed, I find them to be quite reasonably priced
> > > considering they are "real" servo motors.
> > >
> > > The big question, If I decide to use these motors, is what my
> > > reduction ration will be. I need to trade off between torque

and

> > > speed, and the BIG unknown is what torque is REALLY needed to
> > > drive my Bridgeport. I would rather err with a higher reduction
> > > ratio than find myself without enough torque.
> > > If I go with a 3:1 ratio and triple my torque I will get 80

inch per

> > > minute rapids. More than an inch per second SEEMS plenty for

me.

> > Why
> > > do people need such fast rapids on a mill? What do you think

about

> > > even a 4:1 reduction? Will I regret it later? Do I ask too

many

> > > questions? I mostly mill small parts, say 6" on each side or

less.

> > >
> > > A fellow CNC'er here used these same motors on a Rong Fu mill in
> > > direct drive and said they worked, but were at their limit. My

3:1

> > > reduction will triple the torque, and after all, the only forces
> > > different between my Bridgeport and the Rong Fu is the dead load
> > > of the larger table. (The Rong Fu leadscrew is also finer

at .1" per

> > > revolution). The cutting forces should be identical.
> > > The BIG question is will I produce enough power with these

motors

> > > to drive my Bridgeport. What do you think?
> > >
> > > Scott