Re: Servo motor question

Les,
Thanks for responding as I posted this question on another board but
didn't get into the sizing to this level. Here's the specs that I
have
KT37.5 Oz-in/A, Max peak current44.5, Max Con. Stall torque300 Oz-in,
Max con. Current 8.9A I have more info if you need it. I feel a 2-1
ratio would be better than the 1-1 I now have but I really don't
want to go into the Z and X-axis if possible the Y would be simple.
I'm running these off of G340 20 amp limit. If these motors are
capable of using the 1-1 that would be a cost and time saver.
Thanks Harry

-- In CAD_CAM_EDM_DRO@yahoogroups.com, "Leslie Watts"
<leswatts@a...> wrote:

> I would certainly stick with the servos. They
> never slip steps!
>
> As far as direct drive...that is fine as long as you don't
> exceed the continuous current rating of the motor. More typically
> with a 5 TPI screw servos are timing belt reduced 2 or 3 times.
> Direct drive would give you as much as 360 ipm. I doubt you need

anything

> like that so a 2:1 reduction would double your torque
> for heavy cuts and still allow 180 ipm. Effective rotor inertia
> would be quadrupled- but probably no problem at all with that.
>
> Looks like you may have 750 in oz peak and about half that
> continuous. Might be enough if the gibbs are not really tight.
>
> Look up the other specs on your motor if you can. If they
> are not available I can come up with a pretty close estimate
> based on a physical description and some simple tests.
>
> At that point you can measure the current with say a 0.1 ohm
> shunt and a voltmeter. The G340 may also have a current monitor

output

> that you can use without a shunt.
>
> That can be compared to the continuous current rating of the motor.
>
> Les
>
> Leslie M.Watts
> L M Watts Furniture
> Tiger Georgia
>
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> -----Original Message-----
> From: harry32002001 [mailto:harry320@c...]
> Sent: Tuesday, June 15, 2004 2:28 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Servo motor question
>
>
> Hi Group,
>
> I have a BP Series 1 that had a Boss 5 control driving the big old
> finned stepper motors. I switched out the steppers with some extra
> servomotors and share the drive system that I use for my plasma.
> Here's my question for you motor experts, would it be a better

match

> to use the steppers as opposed to the servos? The reason I ask is
> the feed speeds I'm running I.E. 20IPM with a .200 ballscrew and a
> 1/1 on motor have the servo running at 100RPM. I'm I hurting the
> motors and will they last at this speed? They seem to work fine.
> Reading the board started me thinking about this, as I read

steppers

> have low speed torque and servos like higher RPMs. If would seem
> steppers would be more appropriate for this speed range. However

the

> Centroid conversion uses a 1/1 ratio with servos! Maybe they work
> with brute power. The servos I using have a Kt 37.5 Oz –in/A,
> drivers are G340. Any suggestion or info would be appreciated.
> Thanks Harry