Re: Bridgeport retrofit servo questions 1:1 ratio

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.

If I do have issues with it not being able to put out enough torque
at lower speeds, then I will have to change out the pulleys for a
higher ratio. For now, we'll call it experimentation. ~ although I do
think that it would be a better setup if reduced to at least 2:1.
Using the KISS method for now to get into the ballpark...fine tuning
and tweaking to follow.

I hope to document the entire conversion so that when I do get it
done right, others can just follow my recipe and not have to spend
countless hours and days wondering, guessing and wasting $ on things
that don't work. I think there are a number of people out there in
the same boat as me with good mechanical ability that simply are not
willing to pay a middleman $4k+ for motors, drivers and a power
supply. Look how many people get yanked on Ebay buying those Ametek
motors at a 1500% markup...and they are still not good enough for
their conversion.

I'm thankful that there are groups like these available for us to
bounce things back and forth on...to me it is 100% American ~ Better,
cheaper, faster & 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 <rogersmach@y...>
wrote:

>
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> braidmeister <braidmeister@y...> wrote:
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>
> 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

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