Re: Motor Coupling - Was: unbalanced load

--- In CAD_CAM_EDM_DRO@y..., cadcamcenter@y... wrote:

> John Stevenson wrote:
>
> > What was needed was something nearly rigid but with no free play.

I

> > made the first one up and tried it and it worked fine. On seeing
> this
> > the manufacturers changed to a solid one piece nylon coupling but
> > these just sheared the keyways and grub screws. We came to an
> > arangement and they now fit this type shown.
>
> Nice gadget you made. Is the main objective of the nylon

intermediary

> to absorb impulse shock (leading a a very tiny "time-lag"?
>
> The gadget must be machined to very tight tolerance? which mean

that

> it will not help if the shafts are not coaxial?
>

Peter,
This was the whole idea, to be as ridid as possible but allow some
shock movement. Just like a plastic faced hammer.
For obvious reasons the shafts need to be as coaxial as possible
anyway. We get round this by machining the bearing housing and motor
mount as one piece with the bearing locations and the motor location
flange all machined at the same setting.
The coupling is made with under size holes in both steel pieces. I
then have a steel jig piece that replaces the nylon block with short
location diameters on it to fit the undersize holes. Then drill and
ream the two holes in both steel pieces. This ensures that they line
up exactly. I then bore and ream one hole in one steel half to
finished size, assemble the whole coupling and using a stub mandrel
to fit the reamed hole I then bore the last hole. This keeps the
whole coupling coaxial.
Just to finish off I mount on another through mandrel and take a
light skim over the outsde just for looks.

JS