Re: [CAD_CAM_EDM_DRO] Re: Helical Couplings

I'd have to disagree Doug.

I've got some catalogs here at home that list helical slit type couplings as
having ZERO backlash.

I suppose if they are made strong enough that would be true....which
indicates to me, you might as well just use a solid coupling.

Smoke

>Bill,
>
>It's my impression that helical couplings are not the best for use in
>a precision machine. I notice the listing in my McMaster catalog
>says "with little wind-up or backlash". Doesn't that imply they
>have wind-up & backlash?
>
>How about the bellows type, they are listed as "no backlash". Of
>course, they cost more than 2X as much.
>
>This coupling problem is one reason I feel a number of manufacturers
>use a cog belted arrangement. I don't recall ever looking at the
>couplers on any large production CNC's to see what they're using. Do
>you know?
>
>thanks,
>
>Doug
>
>
>--- In CAD_CAM_EDM_DRO@y..., "William Scalione" <wscalione@n...>
>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@d... Thanks.
>>
>> ps. these are needed for servo motors, I got running with gecko
>G340 drives. If
>> anyone is considering stepper motors, I would strongly suggest
>using servos instead.
>> They are much smoother with no missed steps common with steppers.
>The drives
>> are cheap enough for the step and direction servo drives and the
>motors can be
>> had for a lot less than stepper motors of comparable size on ebay.
>I can get 350
>> inches per min on my machine now, and I haven't even tuned the
>drives yet. This
>> is much better than I could get with steppers, and I had good
>Compumotor 175V
>> S drives microstepped to 1000 ppr. Thanks Marriss for the great
>drive.
>>
>> Bill
>>
>>
>> [Non-text portions of this message have been removed]
>
>
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