Re: How to you make a 1/8" collet on a 1/4" shaft

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "deansala" <adsala@p...>
wrote:

> Dave,
>
> Ok colleting the shaft end is a pretty good idea but...and I have
> thought of this..how in the heck can I guarantee that I can ream an
> 1/8" hole perfectly centered in a 1/4" shaft. I have have a pretty
> rigid lathe and have center drills, of course, but I have found

that

> sometimes my holes can get off center. At 30,000 rpms, this might
> produce vibes. Maybe you can suggest a lathe technique that will
> guarantee centerness of my hole. I guess I can use the same idea

when

> threading the shaft as well. Probably not as critical but may

lower

> vibrations.
>
> Thanks
> Dean

Boring a 1/8 hole does make for some pretty tiny work, but it is not
impossible.

I checked MSC and they offer a boring tool for smaller sizes. I
goofed and hit the minimum diameter as 0.015" thinking it was jsut
over 1/8 but could be ground down.... then I realzed I had one too
many zero's ! yeah, they have a boring bar for boring a hole fifteen
thousandths !


08052029 is a boring bar for holes 0.1" so would work.

Min. Bore 1 ⁄16

Max. Bore 5 ⁄16

OAL 2 inches

HSS - 08052011 $19.93

Carbide Grade C-2 - 08051013 $37.21

it looks like it would do a 1" deep hole.
caution about hitting the wall is approprate.

for this sort of work, I drill, then bore to align the hole, then
drill to close size, but on this tiny stuff, boring to size for a
reamer or to final size might be more approprate.

it would be worth a try in some sample stock part.

as to the second approach, the adapter, since you can do all the work
from one side of a piece, you can control the concentricity of the
whole thing. and don't forget to turn the OD at the same time.

On this, I would mill some flats in the body to allow you to hold it
while tightening the collet and not put pressure on the spindle.

Dave