Re: How to determine Torque from these motor numbers?

Here's how you go about it:

1) If 60VDC gives you 1,500 RPM then 40V gives you 1,000 RPM. That is
the motor's velocity constant (Kv) and is 40V / KRPM.

2) The torque constant (Kt) is always 1.351 * Kv. For you Kt is 54 in-
oz per amp (1.351 * 40).

3) I will assume your 1.6 Ohm reading is the accurate one. The motor
is rated at 30VDC. This means the motor will draw 18.75 Amps while
stalled at 30VDC (30V / 1.6 Ohms = 18.75A).

4) Using (2) and (3) gives you a stall torque of 1012.5 in-oz (Kt
times 18.75A).

5) Assume the max continuous torque is 20% of stall torque. That
makes your continuous torque 200 in-oz. Your motor will draw 3.7A
delivering that torque (200 / 54).

6) Your motor no-load speed will be 750 RPM at 30VDC (30V / Kv = 0.75
KRPM, KRPM = 1,000 RPM).

7) Your RPM at max rated torque will be 600 RPM (100% - 20% = 80%,
80% of 750 RPM = 600 RPM).

8) Your power output at 30VDC will be 88.8 Watts (600 RPM times 200
in-oz / 1351 = 88.8W).

Hope that helps.

Mariss

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Earl" <colin@v...> wrote:
> Howdy all again.. hope everyone is having a great holiday.
>
> I have some Ametek DC motora here with a few more specs. How do i
> derive the Torque from these numbers, or is more data needed?
> So far I have found out:
>
> Resistance is about 1.7 Ohm, useing the following readings when
> applying the following to the motor with the shaft locked:
>
> 10.5V drew 6.5A = 1.6 Ohm
> 16.5V drew 9A = 1.8 Ohm
> (my meters wont go above 10A reading)
>
> "30VDC nominal" is printed on the motor, but seems to want to run
at
> higher voltages.. it is OK to run it above 30VDC?
> No load resulted in these numbers:
>
> 30V .58A = 720 RPM
> 50V .67A = 1260 RPM
> 60V .73A = 1500 RPM
>
> Like I said, Id like to know the Torque of these motors, as well as
> if they are a good canidate for a small/medium CNC mill project
> useing Geckos. Ball screws are yet to be obtained.
>
> Thanks for any help (again). :)
> Colin