Re: [CAD_CAM_EDM_DRO] lb/in to oz/in

John Dammeyer wrote:

>A motor that provides 14lb/in torque applies a force of 14 lbs 1" away from
>the center of the shaft. With 16 oz per pound that's 14*16 or 224 oz-in of
>torque.
>
>John Dammeyer
>
>
>
>>-----Original Message-----
>>From: CAD_CAM_EDM_DRO@yahoogroups.com
>>[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of danieltmedlin
>>Sent: Wednesday, May 31, 2006 6:38 PM
>>To: CAD_CAM_EDM_DRO@yahoogroups.com
>>Subject: [CAD_CAM_EDM_DRO] lb/in to oz/in
>>
>>
>>I have two 14lb/in, 100v, 34 amp, 4000rpm, and servomotors. What is
>>the oz/in equivalent?
>>
>>What would be the closest equivalent in a stepper motor?
>>
>>

Something doesn't register right here! this is a 100 * 34 = 3400 W
motor, equivalent to
4.5 Hp. 224 Oz-In seems WAY too low. First, I think the torque rating
is continuous or
stall torque, and at a much lower current than the 34 A, which must be
the peak
current (and torque) rating. The Ke is 100/4 (100 V/4.0 KRPM) = 25, and
so the
Kt can be calculated as 25 * 1.35 = 33.75 Oz-In/Amp. At 34 A that gives
1147
Oz-In! Ahh, that sounds like a much more reasonable figure. And, the
224 Oz-In
would be developed at 6.6 A, which might be the stall torque.

These are killer motors, and there IS no equivalent stepper motor, period.
You can get 1200 Oz-In stepper motors, but that is holding torque, at zero
speed. The running speed is FAR less, and you'll never get a stepper up to
4000 RPM under load. These motors can deliver full rated torque at nearly
the full speed (depending on power supply voltage).
Are these SEM motors? Those numbers look slightly familiar.

Jon