Re: [CAD_CAM_EDM_DRO] Helical Couplings

I prefer to limit helical couplings to feedback linkages, using other types
for torque. They act like springs to the extent that when you turn them
one way they tend to lengthen and tend to shorten when you twist them the
other way. If you tune the servo for high performance they can set up an
oscillation which will put thrust loads on bearings. It also forces you to
consider thrust loads on the motor mount, which would otherwise only take
torque loads. If you tune too tightly you can introduce an unstable
condition. When that happened to me a 1/2" coupling blew up with pieces
going in all directions before I had time to hit the kill switch. It was
pretty exciting, people came running from all directions to see what the
noise was about. I talked to the guy who invented them once. Nice guy,
but somebody stole his business by copying the design.

Bellows are cool, so are the riveted disk kind.

G. Jackson


At 11:11 AM 2/17/01 -0600, you wrote:

>Anybody here have any 1/2" helical couplings in their junk box they want to
>sell?
>I figured I would ask here before I spend the big bucks for new ones. Please
>contact me ____OFF LIST____ at scalion@.... Thanks.
>