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Thread: Sight base conctruction

  1. #1
    Join Date
    May 2001
    Location
    Colorado
    Posts
    223

    Default Sight base conctruction

    I am making sight bases for a rifle. The back one is easy as the mounting area is all the same diameter. The front base mounts on a taper. Any tips or tricks to match the bottom of the base to the barrel taper?
    Jim

  2. #2

    Default

    a tapered mandrel and sandpaper.

  3. #3
    Join Date
    Dec 2006
    Location
    North west California
    Posts
    1,096

    Default

    Once they are fitting the barrel mount them and set up the rifle so the bases can be machined true and to fit the scope rings. You do not want the scope to be under a strain or bent.

    Fitting the base to a tapered barrel can be done with a thick epoxy, just put a good release on the barrel. This is if you are having great difficulty fitting metal to metal.

    Bob

  4. #4
    Join Date
    Sep 2017
    Location
    Long Beach , Ca.
    Posts
    50

    Default

    I would bore a hole the size of the barrel in a diameter big enough so that you could segment pieces off and shape them to size .

  5. #5
    Join Date
    May 2001
    Location
    Colorado
    Posts
    223

    Default

    I have an ball end mill that is smaller diameter than the rifle diameter at the front end of where the rifle base is located (smallest diameter). I milled the base with that. Now sanding is in my future. It is the taper that has me "concerned" as I don't want to over sand the smaller diameter end while removing more material at the large barrel diameter end.

  6. #6
    Join Date
    Dec 2006
    Location
    North west California
    Posts
    1,096

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    Layout fluid or a felt tip pen will allow you to see where the metal is to be removed. First mark the base then place it on the barrel where is to be attached, rotate base slightly and you will see on the base where it is touching the barrel. File ,scrape, or sand the high spots until you get full contact. This will take a long time to get perfect.

    Bob

  7. #7
    Join Date
    May 2001
    Location
    Colorado
    Posts
    223

    Default

    Quote Originally Posted by Bob Ford View Post
    Layout fluid or a felt tip pen will allow you to see where the metal is to be removed. First mark the base then place it on the barrel where is to be attached, rotate base slightly and you will see on the base where it is touching the barrel. File ,scrape, or sand the high spots until you get full contact. This will take a long time to get perfect.

    Bob
    I hadn't thought of that. Thanks!

  8. #8
    Join Date
    Jan 2010
    Location
    Kansas City area
    Posts
    5,557

    Default

    You could put the barrel with one end in the chuck and one end in the live center. Then set the compound slide parallel to the tapered part of the barrel where the mount fits with an indicator running along the side of the barrel. Once you have the compound set, remove the barrel and put a piece of round stock in the chuck. Drill a hole smaller than the barrel, then use a boring bar to make the hole tapered. Check the fit of the tapered hole on the barrel until it slides on to the correct position on the barrel. Section a piece off for the base and screw or silver solder it to the barrel. Mill the height down to whatever it needs to be. All told, pretty easy lathe job.

  9. #9
    Join Date
    Mar 2010
    Posts
    1,067

    Default

    There is no need for full contact over the entire base area. No gaps at the base edges with a narrow contact land behind the edge ( maybe 1/8") is sufficient. Anything more that that buys nothing whether you solder or screw the base down and there is no chance of the base rocking.

    RWO

  10. #10
    Join Date
    Apr 2018
    Posts
    5

    Default

    Excellent idea about taper boring Toolguy . I think it would takes less time than sandpaper and get perfect results .

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