Earl,
Older chucks were made better. I bought a Jacob chuck at Sears
years ago. It was pittyful. I took it back and exchanged it for one
sitting in the back of the pile in an older style box. The box said
Made in USA and it was all taped up. I took it as an exchange. It was
dead on. Remove the collet off the Dremel and check the runout of the
Dremel off the inside lip of the shaft. You should see alot less
runout. Dremel collets are not well made. Paul Jones makes and sells a
spindle that has less runout than anything out there for the price.
John
--- In
Homebrew_PCBs@yahoogroups.com, "Earl T. Hackett, Jr."
<hacketet@c...> wrote:
> A previous post compared a Foredom handpiece and a Dremel for runout
- a serious consideration when using solid carbide bits. They were
0.006" and 0.003" respectively.
>
> So I thought I should go measure what I had available. I had always
been told to use collets for accuracy and to minimize runout. Jacob
chucks were always a no-no when it comes to precision work. My Dremel
and new Foredom #40 both checked out at 0.003". So while I was at it
I checked my 25 year old heavily used Unimat SL, which only has a
Jacobs chuck. It came in at 0.001" of runout and the drill shaft was
dead parallel to the axis of rotation.
>
> So much for conventional wisedom. A collet won't get much better
than that so I guess I know what I'm going to use for my PCB drill. I
always tell my customers that if you don't measure it you don't know
what it is. I should listen to myself.
>
> [Non-text portions of this message have been removed]