Re: [CAD_CAM_EDM_DRO] Re: Keyways or set screws

Frank wrote:

>> A tight-fitting key is very good.
>>
>
> Is that hard to achieve? Will I be able to get a tight fit with a
> keyway broach? Does it take experience to use one properly? I don't
> have a press, can a 9x20 lathe push a broach through aluminium?
>
>

A wallowed-out keyway is fairly hard to repair. New motor shafts and
broached keyways in new pulleys should be no problem.

>> High-torque servo motors can loosen
>> any setscrew, although installing two screws, one on top of the other
>> has been a time-honored trick to keep them in place. Another scheme
>>
> is
>
>> to drill a dimple into the shaft where the screw seats. The best
>>
> scheme
>
>> is locking collars or collet hubs on the pulleys, although these can
>>
> be
>
>> quite expensive new.
>>
>
> Yes, I've seen them. Gates make the perfect set of pulleys I was
> looking for, unfortuantely the local Australian distributors don't
> stock the particular series - they said they would need to import some
> parts from the US and the others from the UK - free shipping would take
> 3-4 months, or I could pay $200 for air freight :(
>

One other trick is to slit the hub and make a clamp ring to compress the
hub. These can grip very tightly.
You can even make your own collet hubs if you want to spend the time. A
lathe taper attachment would be real handy to have, so the taper would
be identical for inside and outside tapers.

Jon