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Thread: Barrel holging jaws

  1. #16
    Join Date
    Aug 2007
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    Kansas
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    208
    TRA What you are saying is mostly true.
    But just remember that the first cnc's and Super high quality machining centers and "21st century" equipment where built with those worn out old manuals lathes and mill's and REAL machinst. I am not any kind of machinist I just really enjoy working those old worn out manual lathes that built what we have to day by real machinist.

    Smile and have a good day
    Chet
    Last edited by coyotechet; 05-18-2018 at 11:42 AM.

  2. #17
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    Feb 2003
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    Jeddo, Michigan
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    3,692
    Wow, TRA has taken what amounted to the opinions of a few and chosen to call those who professed another option to machining as condescending. So be it. I'll not throw fuel on the fire and opine on what other machinists have done for many years.

  3. #18
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    Feb 2003
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    Poetry, Tex.
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    6,091
    You may not want to sell Wayne Shaw short. I value his advice. I use a cathead on either end of the headstock.
    I* do have shorter screws no as old as I am I don't want to get caught up in them. The copper tips hold better than brass. The barrel pivots nicely and I've never had one slip. The notch is there because I was using surplus material, not for balancing.

  4. #19
    Join Date
    Jan 2016
    Location
    Iowa
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    78
    Chet

    Take a look at the marks on the barrel from your jaws.
    You can see one mark bigger than the other. It may be from the barrel being forced to one side of your jaws or not.

    Back three of your jaws away from the barrel leave the fourth jaw under your barrel with the barrel resting in the curvature of the jaw lightly push barrel to the side it will want to rise slightly as it moves. that will put your barrel in a bind!

    It's called school of hard knock's! "I haven't graduated yet"
    I made the same mistake!

    Russ
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    Last edited by R Stiner; 05-18-2018 at 07:15 PM.

  5. #20
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    Aug 2007
    Location
    Kansas
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    One thing I have learned in life no matter what someone is always going to try and find fault. Smile and have a nice day.

    Chet

  6. #21
    Join Date
    Jan 2016
    Location
    Iowa
    Posts
    78
    Chet

    Put a little taper on the nose of your jaws. That way when you hold a smaller DIA barrel the jaws won't be hitting each other.

    By the way the two stickers on the back of your lathe "Priceless!"


    Russ
    Last edited by R Stiner; 05-18-2018 at 08:17 PM.

  7. #22
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    Feb 2003
    Location
    SW Kansas
    Posts
    549

    TRA, just curious

    have you ever chambered a bbl??

    Richard Brensing

  8. #23
    Join Date
    Aug 2007
    Location
    Kansas
    Posts
    208
    Russ I believe you are right, I don't do many barrels smaller than .900 at the muzzle. But I am going to put a taper to the jaws per your good suggestion.
    Thanks. Chet

  9. #24
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    Jan 2016
    Location
    Iowa
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    Chet

    Good luck! & Have fun!

    Russ

  10. #25
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    Feb 2003
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    Jeddo, Michigan
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    I guess you answered the question.

  11. #26
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    Feb 2003
    Location
    Houston, Texas
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    7,004
    I think we have some misunderstandings. The argument probably should be.....independent vs universal.

    We have 12 engine lathes in our shop, ranging in size from a small Monarch EE tool room Lathe to a 44 foot long LeBlond NR.

    Whether a 4 Jaw independent or a 3 or 6 jaw universal stays on a machine is predicateded on what operation the machine will be used for. All of our larger lathes, (30 inch swing and above), don't even have universal chucks. All of our medium and small lathes have both.

    Keep in mind, we are a strictly manual machine shop. The type of work in the industry we serve simply does not lend its self to CAM or other types of numerically controlled machines.

  12. #27
    Join Date
    Feb 2003
    Location
    Tennessee
    Posts
    6,347
    EASE UP GUYS.. If you are chambering through the headstock and using an outboard spider, if, in the chuck end, you will simply chuck on, at each jaw, about 1/4 of a pre 1982 penny you will have plenty of holding power while the barrel is free to not be distorted by the shape of the chuck jaws.



    ,

  13. #28
    Join Date
    Dec 2006
    Location
    Branchville, NJ
    Posts
    436
    Quote Originally Posted by JerrySharrett View Post
    EASE UP GUYS.. If you are chambering through the headstock and using an outboard spider, if, in the chuck end, you will simply chuck on, at each jaw, about 1/4 of a pre 1982 penny you will have plenty of holding power while the barrel is free to not be distorted by the shape of the chuck jaws.,
    I use a piece of 1/4" dia. copper wire wrapped around the barrel for chuck jaws to bite on. Many ways to get the results you want with the equipment that you have.

  14. #29
    Join Date
    Apr 2014
    Posts
    32
    Quote Originally Posted by R Stiner View Post
    Chet

    Take a look at the marks on the barrel from your jaws.
    You can see one mark bigger than the other. It may be from the barrel being forced to one side of your jaws or not.

    Back three of your jaws away from the barrel leave the fourth jaw under your barrel with the barrel resting in the curvature of the jaw lightly push barrel to the side it will want to rise slightly as it moves. that will put your barrel in a bind!

    It's called school of hard knock's! "I haven't graduated yet"
    I made the same mistake!

    Russ
    To me, I would think that the least number of contact points the better. Four is certainly a minimum. Also, I would think that the contact points, or jaws, should be radiused in the front-to-back direction (along the barrel's axis), like the radiused noses of the threaded studs, so that when the spider is adjusted, which will incline the barrel, that the barrel is free to pivot on these radiused contact points. Any "depth" to these contact points will tend to hold the barrel like the flat jaws of a vise and not let it pivot.

    A maybe even better "jaw" design might be one where the contact parts are not radiused studs but rather straight "bar" contacts, maybe 1/4" long say, that are radiused front-to-back. This way when the barrel is inclined by adjusting the spider and therefore the barrel, where it is being held by these contacts, should skew off the center axis of the spindle (while centering the throat area) the straight bar contacts will still be in contact with the major O.D. points on the barrel whereas the radiused points of the studs will go off-axis (hard to explain). The three-letter symbol here: lOl depicts how two of the "bar" contacts would look like when viewed on-axis with the barrel. If the barrel, the "O" here, were to slew up or down when adjusted (by the four jaw chuck or the spider) the straight bar contacts would not tend to capture the barrel but allow it to move up of down. The other two bar contacts at the 12 and 6 o'clock positions would do the same in the left-right direction.

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