Message-ID: <3A8E8C9F.ED515BB8@Reganranch.com>
Date: Sat, 17 Feb 2001 08:37:20 -0600
From: Brent Regan <Brent@Reganranch.com>
To: Lancair List <lancair.list@olsusa.com>
Subject: Working with Stainless
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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Stainless steel alloys, particularly 316, require special attention when
cutting. They work harden easily, turning your work piece into a scene from
"Quest for Fire". The secret, as passed down by my father and his father
before him, is to use low speed, heavy feed and lots of coolant. If you
don't need the strength, 304 is easier to work than most of the other 300
series.

Every time the tool bit cuts, it leaves in it's wake a layer of work
hardened material. The object is to keep the cutting edge buried in the
material and cutting deep enough to be under the work hardened layer from
the last pass. Hole saws are a particular problem because they have lots of
teeth.

For cutting stainless with a hole saw,  here is what you want:
Use a drill press, the largest hand drill you have or borrow a geared drill
(like a Milwaukee Hole Hawg) if you can. Select the lowest speed available.
Clamp the work piece down!  An unsecured piece of stainless sheet metal can
turn into a finger Veg-A-Matic faster than you can say "Take me to the ER".
Wear heavy gloves and safety glasses, the chips may be coming off blue hot.
For large diameters, come at the work piece at a couple of degree angle
until the chips start.
Use lots of coolant. Keeping the work and tool cool is more important than
lubrication. Some of the best cutting fluids are no longer available because
they contained low temperature solvents like Methylene Chloride and
Trichloreythlene.
Use lots of pressure as soon as you contact the work. "Don't piss around,
get cutting!" as my Dad used to say.
If you can get to both sides of the work, cut part way from one side then
finish from the other. The burr will be 1/10 as large compared to a hole cut
from one side.

Multiply these instructions times two when working with Titanium and times 4
when working with Inconel.

Happy cutting.

Regards
Brent Regan

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