开云体育

Hi, Gents.

I stumbled across and joined this Group yesterday, and would
participate with your indulgence.
I am endeavouring to patch together an odd "homebake" assortment of
gear of various vintage to build a multiple axis CNC controller.
The history of the project goes back some years to a time when large-
torque stepper motors, power supplies and controllers were
prohibitively expensive or unavailable.
I decided to cheat.
The system I originally envisaged would use a vector type graph
plotter, the motors of which (minimal in*oz torque reqired) are to
drive the mechanical inputs of some lovely little WWII vintage torque
amplifiers which I have, which talk Ft*lbs at the output and could
win arguments with young stilson wrenches. These outputs are to drive
the 1" diameter ball-screws I have for my X-Y-Z table project, or
axis wheels on mills, or whatnot.
My problem is that the torque amplifiers have 50V 3-phase motors
(50Hz, 1/40 hp, 2750 r.p.m.) which are integral to the units.
Repowering them with single phase or D.C. motors would be a mission
and I am attempting to build a 3 phase 50V power supply to run from
single phase domestic supply (230V, 50Hz, neutral-earthed).
I have built a "Rotary Converter" prototype from internet search
info,....which doesn't work....
Can anyone help me with it, please ? Any suggestions for a good CNC
controller ?
I will not take up space here with it again, but can supply details
to anyone kind enough to respond.
Alternatively, someone might want to convince me that I am on a
Fool's mission and steer me toward some particular controller / power
supply / stepper-motor configuration that would be appropriate. I do
not have any Brand-familiarity with CNC gear at present, but am
learning here!
Incidently, the Torque Amplifiers are from 1941 mechanical
analogue "Predictor" units used to coincide artilliery shells with
bombers and set the time-fuses to the time-of-flight. Amplifiers were
used to boost the output of a mechanicat integrator(!) of Euclidean
elegance which involved a disc driving a cylinder via a sphere with
pathetic work capability! Cylinder-angle = INT(Radius of ball
contact.disc-angle).
Now shells are smarter than guns, and everything has gone
digital ......sigh....

Cheers, Gents. Don.

--- In CAD_CAM_EDM_DRO@y..., "Don" <donkiwi@y...> wrote:

My problem is that the torque amplifiers have 50V 3-phase motors
(50Hz, 1/40 hp, 2750 r.p.m.) which are integral to the units.
Repowering them with single phase or D.C. motors would be a mission
and I am attempting to build a 3 phase 50V power supply to run from
single phase domestic supply (230V, 50Hz, neutral-earthed).
I have built a "Rotary Converter" prototype from internet search
info,....which doesn't work....
Can anyone help me with it, please ? Any suggestions for a good CNC
controller ?

Don: Whew!! 1941 bombsite parts...that's a REAL challenge. There
exists sufficent talent in this group to help you design a 3 phase
50HZ converter. It would be my advice to lurk in the shadows for a
few weeks and follow the threads on steppers, servos, controllers and
software. Go to the links the members provide and visit the sites of
some of the members listed. You will discover several things: (1)
The prices are much more reasonalble on all of the components to make
a good CNC machine than they were even two or three years ago. (2)
The mechanical part of the construction is only about 50% (perhaps
less) of the challenge. You will be presented with a bewildering set
of choices for CAD, CAM and Controller Software. You will be forced
to invest a LOT of time in learning whatever software programs you
choose.

My personal advice is to pick up the torque amplifiers, walk to any
open window you have available and toss them as far as you can manage.

Don wrote:

My problem is that the torque amplifiers have 50V 3-phase motors (50Hz, 1/40 hp, 2750 r.p.m.) which are integral to the units. Repowering them with single phase or D.C. motors would be a mission and I am attempting to build a 3 phase 50V power supply to run from single phase domestic supply (230V, 50Hz, neutral-earthed).
I have built a "Rotary Converter" prototype from internet search info,....which doesn't work....

What you really want is a servo amp for AC servo motors (induction motors rather than
permanent magnet brushless). These definitely exist, and are what many of the high-end
machine tools are now using. Yaskawa, Rockwell/Allen-Bradley, etc. are making these
drives now. A rotary converter is not of any use, because it will run the motors at
constant speed. You need a drive that can move the motors from creep to full speed.

Oh, but wait! 1/40 Hp? You can't move a cutting machine with a 1/40 Hp motor. My
underpowered Bridgeport retrofit uses 1/8 Hp DC servo motors, which can produce 1/2 Hp
peaks for a moment.

I think you should find some stepper motors or good-sized servo motors to do the job
directly. Using motors to drive amplifiers to drive bigger motors doesn't make any
sense to me.

search eBay for used servo amps, they do come up pretty regularly.

Jon

In a message dated 11/4/2002 11:17:44 AM Central Standard Time,
elson@... writes:

My problem is that the torque amplifiers have 50V 3-phase motors (50Hz, 1/40
hp, 2750 r.p.m.) <<

WHERE did you come up with "50 V"??? It clearly says "50 Hz.", which is
"cycles" in Fifties-speak, NOT "V[oltage]" !!!!!!!