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Thread: how can i improve the finish of my bbl threading

  1. #31
    Join Date
    Oct 2019
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    820
    most is bbl 416 ss..but i have done cm.
    Quote Originally Posted by Centerfire View Post
    I did not see mention of the type of barrel steel being machined. Is it a 416 SS or a Chrome moly steel?
    Does it make any difference regarding the cutter material, rotational speed, or feed?
    Centerfire

  2. #32
    Join Date
    Jul 2016
    Location
    Surprise, AZ
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    424
    Quote Originally Posted by NezRongero View Post
    Watch "Jet 1024 Threading To A Thread Relief Aided By A Proximity Sensor" on YouTube
    https://youtu.be/1D-HoFgNYFg
    Nez, you have some interesting videos (and not padded with 6 minutes of vapid blather!). I wish you would put a small description on them as I sense a nugget of wisdom in each. Watching the one where you were (apparently) checking the squareness of the front of an AR upper receiver - I'm very curious if you have more data from doing this. I'm looking to confirm my prejudices, of course. I maintain that most uppers are square and that the lapping kits I've seen for sale are a useless gimmick. BUT, I've only had the opportunity to check a few (all square). Have you found any that are seriously out of square with the bolt passage?

    Regards,
    GsT

  3. #33
    Join Date
    Feb 2004
    Location
    Williamson County, Texas
    Posts
    324
    Gene,

    Thank you for the kind words.

    The worst I have seen is about 0.003 and front sort of rounded, that it took about .004 to clean up. Some of the other problems with the ARs are the barrel extensions. I can check everything including thread runout like Jackie described at one point, but when BE is screwed on and indicate it, it will be swinging 0.003.

    Do all these matter, hard to quantify, I have not done any systematic testing to validate any. I put them in the it-cant-hurt category. I am not in the business, I am retired, time I have. Supporting 18 kids in the State Team keeps me busy.

    If you can believe this guy, this is so far the only write up I've seen on incremental improvements on the platform verified on a machine rest.

    Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half. - Free Online Library
    https://www.thefreelibrary.com/Maxim....-a05207138981

    These were taken last night, the kid wants to see how straight his barrel is. Thread was cut with uncoated carbide laydown for Aluminum at 34 RPM on the variable speed 1440, untouched, just cleaned up thread with brush, and air blown. The BE is pretty straight. Got it from WOA.


    Watch "12 Aug 2020 Testing Thread Runout" on YouTube
    https://youtu.be/CEFUO028lVI

    Watch "12 Aug 2020 Testing BE Runout" on YouTube
    https://youtu.be/CM434kOxx0s

    On squaring the AR10 face I have been using a split ring (borrowed from Mike Bryant) and TS spider screwed on to a Royal live center.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by NezRongero; 08-14-2020 at 01:19 AM.

  4. #34
    Join Date
    Jul 2016
    Location
    Surprise, AZ
    Posts
    424

    Thank you!

    Quote Originally Posted by NezRongero View Post
    Gene,

    Thank you for the kind words.

    The worst I have seen is about 0.003 and front sort of rounded, that it took about .004 to clean up. Some of the other problems with the ARs are the barrel extensions. I can check everything including thread runout like Jackie described at one point, but when BE is screwed on and indicate it, it will be swinging 0.003.

    Do all these matter, hard to quantify, I have not done any systematic testing to validate any. I put them in the it-cant-hurt category. I am not in the business, I am retired, time I have. Supporting 18 kids in the State Team keeps me busy.

    If you can believe this guy, this is so far the only write up I've seen on incremental improvements on the platform verified on a machine rest.

    Maximizing The AR-15: A former military armorer reveals his secrets for cutting AR-15 group sizes in half. - Free Online Library
    https://www.thefreelibrary.com/Maxim....-a05207138981

    These were taken last night, the kid wants to see how straight his barrel is. Thread was cut with uncoated carbide laydown for Aluminum at 34 RPM on the variable speed 1440, untouched, just cleaned up thread with brush, and air blown. The BE is pretty straight. Got it from WOA.


    Watch "12 Aug 2020 Testing Thread Runout" on YouTube
    https://youtu.be/CEFUO028lVI

    Watch "12 Aug 2020 Testing BE Runout" on YouTube
    https://youtu.be/CM434kOxx0s

    On squaring the AR10 face I have been using a split ring (borrowed from Mike Bryant) and TS spider screwed on to a Royal live center.
    Thanks for the response and the links.

    GsT

  5. #35
    Join Date
    Sep 2003
    Location
    Oriental, NC
    Posts
    1,054
    I did a lot of work for one manufacture that used a BE for a large caliber bolt gun. Being the curious type I immediately started checking the BE's. Curious = CYA some of the time. All it took was one and I went through 123 to get 30 I would use. Those 30 barrels showed a marked improvement in accuracy over previous barrels. I checked concentricity as well as run out on the inboard and outboard side of the shoulder. They changed suppliers and the story had a happy ending for the next 400 or so barrels.
    Some of the same people involved in that project moved on to other companies and now I get good extensions for their piston gun.
    Last edited by Dave Tooley; 08-14-2020 at 08:26 AM.

  6. #36
    Join Date
    Feb 2003
    Location
    Poetry, Tex.
    Posts
    7,137
    Quote Originally Posted by GeneT View Post
    Thanks for the response and the links.

    GsT
    Gene, I just received my Wife's upper that Nez built for her. Work is over the top!

  7. #37
    Join Date
    Jan 2009
    Posts
    17
    Quote Originally Posted by NezRongero View Post
    Please allow this rookie to participate. I have a dedicated Jet 1024 for chambering AR15 barrels with compound sort of permanently set for taper boring. Even with this little lathe I thread plunging in with the cross slide. I use laydown inserts for aluminum. They cut 416 SS real well.

    Watch "Jet 1024 Threading To A Thread Relief Aided By A Proximity Sensor" on YouTube
    https://youtu.be/1D-HoFgNYFg
    What kind of repeatability are you getting from your prox? I went with a 5 micron limit switch Iím getting about .0005 at 150 rpm
    https://youtu.be/Ncc72aKgzVY

  8. #38
    Join Date
    Feb 2004
    Location
    Williamson County, Texas
    Posts
    324
    Quote Originally Posted by killswitch505 View Post
    What kind of repeatability are you getting from your prox? I went with a 5 micron limit switch Iím getting about .0005 at 150 rpm
    https://youtu.be/Ncc72aKgzVY
    I don't have a DRO on that 1024, just a dial indicator. It gets to 0.001 or whatever you can accept as the repeatability of the dial indicator. I set the indicator to zero where I want to stop for a given RPM, needle stops on zero. What that is in actual precision, never bothered to verify and don't have the means to do so. So, I just accept what the dial indicator is telling me. For threading to a relief, it is more than adequate.

    I do not use the prox to turn to shoulder.
    Last edited by NezRongero; 08-15-2020 at 07:00 PM.

  9. #39
    Join Date
    Jan 2009
    Posts
    17
    Shoot man thatís why I built mine takes the pucker factor out of threading to a shoulder I went from threading at 70 rpm to 300 ive kind of settled at 150rpm and I never have to disengage the half nuts

  10. #40
    Join Date
    Feb 2004
    Location
    Williamson County, Texas
    Posts
    324
    Quote Originally Posted by killswitch505 View Post
    Shoot man thatís why I built mine takes the pucker factor out of threading to a shoulder I went from threading at 70 rpm to 300 ive kind of settled at 150rpm and I never have to disengage the half nuts

    I do thread to shoulder when I have to, but thread relief when not needed depending on the barrel extension or flash hider/brake/suppressor adapter. Some have reliefs, some don't. The only bolt gun I ever work on is my brother's glued VFS. That I thread close to the shoulder so when I set back the barrel the extended thread looks decent. It does not make a difference if the thread is interrupted, it just looks pleasing when there is not a big gap between the old and the new thread.

    Here is what I use when working on my brother's barrel. See how close the center tip is to the right side edge. I spec'ed it for Thinbit to make for me. The item is not a catalog item, but modified from existing design.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by NezRongero; 08-15-2020 at 07:27 PM.

  11. #41
    Join Date
    Jul 2005
    Posts
    714
    Many of the threading tricks (like upside down, backwards, etc.)
    are ways of trying to get a little more precision out of lighter weight
    (and strength) machines.
    Most of the work on smaller fasteners would be done using a
    screw machine cutting lathe.
    They are optimized for smaller threads.

    Sharp steel (HSS is better) works better than carbide especially in smaller tool sizes.

    Having some carbide around can often be handy.
    Make initial rough cuts using carbide, then switch over to HSS SHARP tools.
    No point in making most of the cut with that carefully sharpened HSS cutter.
    The wide availability of diamond tooling for sharpening HSS cutters makes things go very well.
    A fine diamond paddle for the last few strokes on HSS puts Arkansas stones to shame.
    Last edited by brickeyee; 01-08-2021 at 03:35 PM.

  12. #42
    Join Date
    Oct 2019
    Posts
    820
    2000 lbs.....
    Quote Originally Posted by brickeyee View Post
    Many of the threading ticks (like upside down, backwards, etc.)
    are ways of trying to get a little more precision out of lighter weight
    (and strength) machines.
    Most of the work on smaller fasteners would be done using a
    screw machine cutting lathe.
    They are optimized for smaller threads.

    Sharp steel (HSS is better) works better than carbide especially in smaller tool sizes.

    Having some carbide around can often be handy.
    Make initial rough cuts using carbide, then switch over to HSS SHARP tools.
    No point in making most of the cut with that carefully sharpened HSS cutter.
    The wide availability of diamond tooling for sharpening HSS cutters makes things go very well.
    A fine diamond paddle for the last few strokes on HSS puts Arkansas stones to shame.

  13. #43
    Join Date
    Aug 2006
    Location
    Greenwood, SC
    Posts
    89
    Chasing the threads with a die often helps to clean them up, too.

  14. #44
    Join Date
    Nov 2006
    Location
    Augusta, Maine & Palm Coast, Fl
    Posts
    6,603

    A friend has

    a Hardinge Chucker, I think it's called, with a threading rig on it that is a cam that pulls the tool way far away from the work when it gets to where it is suppose to stop. Slickest outfit I've ever seen. Would speed up threading by at least 1/2 I'd think.

    Pete

  15. #45
    Join Date
    Jul 2005
    Posts
    714
    Quote Originally Posted by Clemson View Post
    Chasing the threads with a die often helps to clean them up, too.
    Firearms seem to be home to MANY 'non-standard' threads.
    They are carefully designed for the specific function and loading on a firearm.

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