Given this list is a pretty diverse bunch of surplus prowlers, I am
wondering if anybody knows where I can find a couple super low
inertia motors like some older tape drives and other very rapid
positioning equipment used. They are easy to spot once you have seen
one, imagine a super large sams club sized tuna can (say 4" tall x
7" dia) with a single portion fruit can on top and shafts sticking
out the top and bottom. A couple big knobs for brushes etc. and if
you touch the shaft it turns like nothing is there, very low inertia.
Here is a picture, and you can even see the two in the middle still
have some sort of tape drive capstan thing I think.
<http://www.mindspring.com/~sdinc/pages/contra_p22.html>
You can see they vary from pricey at C&H (which is the only place I
am finding any in stock) to $5 or $10 at most swapmeets, and around
$25 at cheaper surplus joints. Still much cheaper than the new price
around $600. What I need is one, maybe two if the price is good and
they meet these specs;
Motor Moment of Inertia (Jm) = 0.0007 to 0.0009 oz/inch sec^2
Torque constant (Kt) = 9 oz/inch per Ampere (for 1 Ohm motor, ie. Rdc = 1 Ohm)
Torque constant (Kt) = 14 oz/inch per Ampere (for 2 Ohm motor, ie. Rdc = 2 Ohm)
Drive shaft = 3/8 in. (diameter)
"Figure of Merit" (FoM) = Kt/(Square root of Rdc) = 9.9 oz-in of
torque per watt disipation
Any of the following should do, but I would prefer a 4VM82 due to
higher heat rating.
Pacific Scientific
4VM62 XXX
4VM82 XXX
Yaskawa
S-12-B
Electro-Craft
M-1140
The XXX just means the numbers don't matter. I had a 33VM62 that was
brand new in my hands at TRW swapmeet, but haggling fell through at
$7, and good that it did as that one has too low torque. For the
curious this is to be used as the drive motor in a Contrabass
subwoofer. I do have some real plans to play with one as a computer
controlled positioning system. Sorry if its too off topic for some,
but it is an old computer motor.