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  1. #1
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    I have been working with a cartridge, designed for IHMSA, that I would like to create a reamer. I have built reamers for straight-walled cartridges, with excellent (if I say so myself) result. But now I want to try my hand at making a bottle-necked reamer.

    I have a couple of questions. And I love to hear any responses that the forum would like to provide.

    1) When the reamer blank is mounted between centers in the lathe, how to I accurately measure, and machine, where the shoulder starts on the body of the reamer?

    2) Is it necessary to undercut the reamer flute at the shoulder/neck junction?

    3) I've seen several chamber prints, which call for a 1/8" or 1/4" radius on the shoulder/body junction and on the shoulder/neck junction. Is that all necessary to machine into the reamer? What's wrong with sharp angles?

    4) Are there disadvantages/advantages for having a tapered neck (.002" - .005" per inch)? Is that to help ease case extraction?

    5) Is O-1 still one of the better tool steels to use for a home machinist when making chamber reamers? I do have a heat treating oven, with a pyrometer. Would A2 be a better choice?

    Thanks for all replies.

    _kevin

  2. #2
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    a tapered neck will mess with the neck tension for accuracy, there is a reason for having that straight. You are forgetting that the brass springs back after the shot is fired.

  3. #3
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    Kevin..#1 classsicly, u wud use a surfaceplate ,vernier ht.ga. ,dye & mark out ...or take the easy way out & use ur verniers....practically, ,i rough scribe & cut my neck to d. + .015 ( grinding allow. ,actually .010 has been enuf )for desired length plus xtra inch + or so for pilot/lead.....now cut shoulder ( ( u cud actually plunge grind it & not turn at all , but i generally did turn it ) u have now establishe neck position ....turn body diameter now (cyllindrical ,...easier to grind taper after hrdng.) ......sooooo neck marking out became non critical,,,,,,,,,,
    #2IF I UNDERSTAND UR ?, undercutting when grinding shoulder ( into neck ) is a freebie that makes sure u went far enuf, since the neck is cyllindrical & has already been reamed to size from the front angle flutes....bu undercutting on lathe , u only make it easier on holding the EDGE of ur stone from wear ( i dont bother ,but then i have only made my own reamersin single lots)
    #3 brass always has a radius of sorts ,cuz it doesnt completely flow outinto shldr.,...have seen radius on cartridge drwng, but see no need to grind it on reamer.& have not done so
    #4 taper ...already answrd...unnecessary . ...i did grind some on a match 22 rf reamer 40 yrs ago to keep case max aligned , & did get some hummer barrels , but w/22 r/fire ,its a crap shoot , & unable most times to pin down positives /negatives

    #5 ..01 is cheap , easy to work with , ....I get less than .010 runout hardening w/ torch ,reamer turning at 200 rpm in drill press, quenched vertically from below w/ ATF.......
    other tool steels may cut more chambers ,but i dont need my reamer to cut hundreds of chambers ( & if i did , i wud sharpen it)..keith francis suggested 07 for beginners, but when i looked for it , a loooong time back , i came up negative...& i have no experience w/ any others except W-1 , & i dont want any more of that kind of experience..........

    i made up 2 pages of notes to myself on procedures , the last pair of reamers i made( didnt want to have to refigure how after 10-20 yrs between making them ...kind of silly ,now since i am 72 , & most likely thru playing w/ non standards)..a copy is available for a SASE if u desire....


    best wishes
    docn8as

  4. #4
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    Kevin ...i really shud state that x/cept for a very short time in the 50's,(starvation ) riflesmithing was an avocation , ( & a lot more enjoyable )...these are MY ways , not having had the benefit of a tutorial, & may certainly benefit from superior knowledge ,examination & criticism.....


    best wishes
    doc n8as

    if u think there is a dearth of info on reamer fab, thats abt how the situation was 50 yrs ago when i stumbled along in the darkness w/ barrel fitting ......much better now!

  5. #5
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    Doc:

    That's excellent information. And I'd like to hear other's methods, as well.

    When I was growing up (a relative term to be sure), I had the disticnt pleasure to have a family friend who was an incredible gunsmith, actually a friend of my grandfather. And he became a life-long friend of mine. He showed me many things in the machine shop, but he passed away before we got to the "chamber reamer" section of the "course".

    To expound on undercutting the reamer flute at the Shoulder/Neck junction... Seeing that this is the part of the reamer that cuts 90% of the metal removed from the chamber, that also is the part of the reamer that gets dull the fastest. I believe that by undercutting that section, makes it a bit easier to sharpen by not having to be as critical where to stop sharpening before getting into the neck portion of the reamer. (It's not considered lazy, if you can mask it as efficiency...)

    I have read Guy Lautard's Machinist Bedside Reader #3, which talks about a conversation that Lautard had with Keith Francis, and there is quite a bit of information on sharpening, but not much on the layout and initial machining of the reamer.

    In the MBR3, Lautard recommends a "Ruby" stone to use for sharpening, does anyone have experience with that type of stone?

    Doc, I'd like to get a copy of your notes for reamer fabrication, my phone number is: 708-955-6427 (near Chicago, IL)

    Thanks to all,
    _kevin

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    Kevin...fortunate that u had a mentor , & even more that you recogmized & took advantage of your good fortune......

    i still have the "ruby " stone (Germany, barber supply) that i honed my straight razor with for abt 40 yrs ( life is simpler w/ a beard now)....it is extremely fine grain , for finish honing . a tad softer than a HARD arkansas......a medium india is probably all u need ,maybe a fine if u must ...........no idea where to get a ruby now ,nor what the (aagh) cost would be !

    best wishes
    docn8as

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    Brownells still has ruby stones, page 206 in cat #55. Now they show a flat #221 and a knife #291 the knife is $70.35 Hope you were sitting down!

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    http://www.homemodelenginemachinist....s/-Reamers.pdf and get a copy of the MODERN GUNSMITH by JAMES V HOWE.
    Mr. HOWE was a master gunsmith and machinist,this is a two volume book full of great info with detail prints.

  9. #9
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    Hey Kurt,
    Haven't heard from you in awhile. Hope you are doing well. I have had my best results sending Dave Kiff a drawing. It is cheaper and faster than using my machinery to produce. If your ego doesn't get in your way $125-$150 for a custom reamer is cheap. I have all the tools in my shop to produce a reamer, but I can do better, cheaper letting Dave or one of the other reamer people produce it.

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    There are times when you can make the money to buy a reamer(or whatever else you want),by doing jobs that are easier to handle. Unless you just want to do this for the challenge,of course. I have made many things just for the challenge myself.

    I don't see why a ceramic slip stone would not be just as good as a ruby(which is older technology). I sharpen on a diamond bench stone,then a black,then a white Spyderco ceramic stone. In my many years at a museum,I had the money to try out just about everything out there. This is what I have settled upon. Ceramic stones are harder than Arkansas by a great degree,and will sharpen any kind of steel. I made a knife from D2 years ago. My Arkansas stones would not quite get it razor sharp. D2 is very wear resistant. Ceramic stones sharpen it up easily because they are much harder.

  11. #11
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    This is an 11 year old thread that has been resurrected for some reason. I haven't heard from doc for years either. He was a source of much information and quite willing to share.

    There is nothing wrong with knowing how to make your own reamer, especially if developing a new cartridge as the OP was attempting all those years ago.

  12. #12
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    Quote Originally Posted by precision tools View Post
    This is an 11 year old thread that has been resurrected for some reason. I haven't heard from doc for years either. He was a source of much information and quite willing to share.

    There is nothing wrong with knowing how to make your own reamer, especially if developing a new cartridge as the OP was attempting all those years ago.
    Doc posted over in the Antique forum a couple days ago, so he is still around.
    James

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    thread-necromancy.jpg

    Sorry, couldn't resist

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