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From: Gale McMillan <>
Newsgroups: rec.guns
Subject: Re: Info Needed; Half-Reamer
Date: 22 Sep 1996 18:43:33 -0400

P.Feist wrote:

#    I'm looking for information on how to make a "Half-Reamer". A
# Half-Reamer is a reamer (naturally..) that is made with only one "Flute".
# It is simply a cylinder of the appropriate taper or shape with half of its
# diameter removed to provide a cutting edge.
#    I had a chance to examine a half reamer several years ago at a barrel
# makers shop, but didn't have any background on cutting tool geometry,
# releif angles, etc. Now that I do, I don't remember how the thing was
# relieved to cut!
#    I need to make a cheap, easy rifle chambering reamer for a one-off
# project, and thought this might be the way to go.
#    Any information or titles of books that have this information would be
# greatly appreciated, with profuse thanks!
# Regards
# Paul Feist
# Paladin Gun Repair
# (Will Gunsmith for Food....)

Turn the shape you want on a lathe out of a good oil hardening tool
steel like Ketos.  Put it in the drill press and turn it in slow speed
while heating it with a torch.  When it reaches a bright red 1550
degrees lift a can of oil up and quench it while it is rotating.  This
prevents warpage as it is heated evenly.  Then grind it in half being
sure not to over heat it The arc of the wheel will give you a hollow
ground effect which will make stoning much faster.  On any shoulder that
is square to the axis has to be backed off so that it doesn't rub.  With
care a good reamer can be made that will cut slowly but well.  It is not
critical that it be ground exactly in half as long as it is ground at
least in half.  If a pilot is used grind only half of the pilot and
leave half to be a guide. If you feel you need more information feel
free to email me

Gale McMillan

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