Re: [CAD_CAM_EDM_DRO] Re: sprockets?

At 02:49 PM 7/12/02 -0000, you wrote:

>Timing belts are commonly used a very high precision CNC machines
>without problems. From a fabricators standpoint they have advantages
>over inline type connectors. All of the CNC lathes I'm most familiar
>with use timing belt drive systems and those machines hold tenth
>tolerances.

True! They also provide some vibration isolation. I'm using these on my
machines, and last night I ran a batch of parts that held a bit under
+/-.0002".

>The little bit of investigation I've done regarding backlash-free
>connectors indicated to me they require some very serious cash to get
>one with a high enough torque rating for a machine in the B'port size
>range.

It's obviously simpler to direct couple them though. If you can be happy
with precision and developed force obtained from direct drive, the simple
way is a rigid sleeve that couples the shaft and screw end ... the motor
can float on its own bearings, with a simple torque link from the coupled
end of motor to anchor. Such a coupling is nothing more than a bit of
round stock drilled and reamed in one chucking, to appropriate sizes for
the mated parts. Set screws are sufficient to make the joint rigid and precise.

Regards, Hoyt


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