Re: [CAD_CAM_EDM_DRO] Metric bore timing pulley

Alan Rothenbush wrote:

> I need an XL timing pulley with a 5mm bore and I can't seem to find one.
>
> I _could_ maybe machine up a 5mm to .25" sleeve but I'm not quite sure what I'd use for a boring tool; I have nothing nearly that small.
>
> Any ideas ?
>

A single flute of an end mill makes an excellent impromptu boring tool.
Just angle it ever so slightly so only the tip cuts.
I bore all my timing pulleys, they are normally sintered powder
composite, and the center hole is quite often not concentric.
Sometimes it is quite visibly off-center when you start up the lathe. I
turn a ring out of aluminum with about a 1/8" wall first, such that the
ID is a good fit to the pulley OD. I then slit the ring into two
pieces. This can be used for both flanged and non-flanged pulleys. It
allows you to accurately hold pulleys of any tooth count in a 3-jaw
chuck. So, I always try to get the pulleys with too small a hole and
bore. That fixes two problems (diameter and concentricity) at one time.

Jon