Re: Need help with Dyno design

> Wally, Wouldn't it be easier to turn a 2"long X 2.125 dia spool in

the lathe with a 16 tpi groove on its diameter. Mount spool on motor
shaft, wind a cable on the spool with different weights suspended
from it? Steel is .282 pounds per cubic inch to calculate the
standards. Run different Rpm's and distances to see where it skips.
Could run that Eckstein's DRO system with an encoder mounted on shaft
to verify. Or a simple reference mark from shaft to motor body.

>
> Ron

I thought of something like that, but at speeds of 1000 rpm plus you
would need a very long cable.

Wally




--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers <rogersmach@y...>
wrote:

> Wally, Wouldn't it be easier to turn a 2"long X 2.125 dia spool in

the lathe with a 16 tpi groove on its diameter. Mount spool on motor
shaft, wind a cable on the spool with different weights suspended
from it? Steel is .282 pounds per cubic inch to calculate the
standards. Run different Rpm's and distances to see where it skips.
Could run that Eckstein's DRO system with an encoder mounted on shaft
to verify. Or a simple reference mark from shaft to motor body.

>
> Ron
>
> cnc_4_me <cnc4me@g...> wrote:
>
>
> I could use some advice on using multiple motors in parallel for a
> dynamometer load.
>
> I want to build a dyno to give me the torque curve for some

powerful

> steppers I have. The problem I am having is the steppers have so
> much low end torque it will take a minimum of 3 treadmill motors

for

> a load, and I may build the dyno to use 5 load motors.
> The stepper has a running torque of 1208 oz-in and each treadmill
> motor has a maximum torque of 441 oz-in (2.25Hp at 5100RPM 260Vdc

5A).

> The load motors would be connected to each other with 1-1 gears.
>
> To control the torque of each motor I was going to use Masiss¡¦s
> dynamometer circuit. It can be found here.
>
> In the CAD_CAM_EDM_DRO file section
> Files„³circuits¡X>miscellaneous ,circuits„³dynomometer circuit.pdf
>
>

http://f5.grp.yahoofs.com/v1/IA4XQimTsSyrH7uH0OGaenRM5_adVog79qfEKuhBP

> LkLJoZbQOwXh_oohX_HoZciVSJjDU3Y9WBBAQn4vCZL1JcOSV-
> Y/CIRCUITS/Miscellaneous%20Circuits/dynomometer%20circuit.pdf
>
> This circuit uses an op amp to control a few power FET¡¦s to slowly
> energize the load motor.
>
> I am thinking that each motor would have to have its own power FET
> control circuit in order to balance the load. I am also thinking I
> need 1 POT to control all motors and each power FET circuit should
> track together.
>
> With that said I am unsure if this circuit will do that. I think

the

> control POT could be P1 in the schematic and all op amp power FET
> circuits would connect to this point. Then P2 could be used to

match

> the loads. While that sounds good in theory I do not know how well
> these circuits will keep the motor current in sync.
>
> Does anyone have any advice?
>
>
> Wally
>
>
>
>
>
>
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