[ATM] Re: Linking motors to shafts

[David Cohen <davelcohen2000@yahoo.com>]

Look for Lovejoy couplings in McMaster Carr or MSC
(www.mscdirect.com). They are called "shaft
couplings". They are 3-piece couplings.  You need to
get a coupling for the motor shaft and a coupling for
the driven shaft.  They each can be different bore
sizes, in accordance with your needs.  They have keyed
and setscrew versions.  I use the 2-setscrew couplings
- they will work on a  shaft with/without flats, or a
threaded rod. You also need a spider, with is a soft
rubberlike material that allows for some misalignment.
 I used mine with a NEMA 34 stepper motor to turn an
observatory dome - the couping cost less than ten
dollars.

Bear in mind that the spider will allow an initial
twist to occur between the two shafts, the amount of
twist increasing with torque.  That may be a down side
if you're driving a R.A. axis.  The up side is that
the spider does help reduce vibration somewhat - an
unpleasant characteristic that is inherent with
stepper motors. They also make rigid couplings where
no relative motion occurs, which requires very good
shaft alignment.

Try this URL, it should get you started

http://www1.mscdirect.com/CGI/NNDRVSH

I hope this helps.


=====
Best Regards,
Dave Cohen
davelcohen2000@yahoo.com

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