ATM Re: working Sainless Steel

[James P Crombie <jpcrombie@islandtelecom.com>]

  If you do attempt to drill SS you want to use Cobalt HS drills and
keep the speed very low with lots of lubication. A surface speed of
25-50 fpm is a good starting point.   As for tapping a good quality
spiral point tap is recommended and should be used with a tapping guide
to keep it square to the hole and keep it going without backing off
(thru holes) You can use them on blind holes but the chips can jam in
the bottom of the hole.  You can get spiral flute taps but they are
mainly for machine tapping.
  You used to be able to get very effective tapping fluids for stainless
but they contained tricloroethane 1.1.1. and of course are no longer
available.  The sulfer oil is probably the next best thing, but geeze it
stinks :-)
  Mind you,  difficult is relative,  tapping Inconel 718 makes any
stainless look like butter!


>Date: Mon, 21 Aug 2000 07:50:27 -0400
>From: Ina Ron Lippard Renaissance Reproductions <renrepro@together.net>

>Subject: ATM working stainless
>
 >  Stainless can be cut with a diamond saw providing you wish to use it

>as a 'clean-up' cut. As the others indicated, it is best to start with
a
>hack-saw and some new blades.
>
> Tapping stainless can be a 3-ring horror show without the right tools.

>  Especially if you want to tap the end of it straight. Unless you have
a
>  drill-press do not attempt to drill stainless with a hand drill, wait
until
>  your machine shop becomes available again. If you intend to tap the
bar
>  on a side, I'd use a fixture of some kind. As for the actual tapping
is
>  concerned, Peter is correct. Use a drill that is a bit larger then
you
>  would normally use. In this case a 1/4-20UNC calls for a .201 or #7
drill.
>  I would use a #3,or#4. Up around .213. Use black thread-cutting oil.
>  Good luck! Ron



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James P Crombie
Summerside, Prince Edward Island
Canada
Machinist - Amateur Astronomer - CadCam Guy

http://www3.islandtelecom.com/~jpcrombie        My Astronomy website
http://www3.islandtelecom.com/~jpcrombie/rhino/ My RhinoCad web page

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