Tony, If you are drilling stainless, it helps a lot to use cutting
fluid. Machine tool supply stores will have this available (hopefully in
small cans) in various different types for tapping, drilling and general
metal working. For home use, almost any of them will work fine. A little
goes a long way and you will probably find that the drill stays sharp
almost indefinitely. Cutting fluid also improves tool life for regular
steel and helps for clean cuts in aluminum.
I always remember drilling some SS boat fittings a long time ago and
watching in wonder as the end of the drill bit glowed red and welded
itself to the part !!
Cheers, John, A099
Tony Krzyzewski wrote:
>
> >
> >However, I studied it a bit more closely this time and it appears to me
> >that some of the drillings have almost started to break through to the
> >inner surface - am I imagining it, or are there slight bumps on the visible
> >part on the inside? If so, this is probably bad news ....
> >
>
> Not true. The marks you see on the inside are merely heat marks as a result
> of the drilling. I ended up blunting two brand new 3/16 drill bits on the
> stainless steel and towards the end I think the piece was getting quite
> warm. Making all of those dimples really takes it out of the drill bit.
> Doing a blind finger test on the inside of the tube produces not detectable
> bumps.
>
> >Any drilling like this needs to be done to a carefully set depth stop using
> >a bench drill, _not_ a hand-held one, with the workpiece supported in a
> >precisely repeatable way for each hole location.
>
> Which is the technique that I used and documented on the site.
>
> Tony
>
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