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  1. #1
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    831

    Default Pratt Burnerd 3 Jaw Chuck Outside Jaws - N.O.S.

    These Outside Jaws are for 2.75" and 3.0" chucks respectively. They are New Old Stock and will only fit the applicable "Obsolete" chucks. $20 per set of 3 if picked up from Riddells Creek Vic. or $30 delivered throughout Australia.

    Pratt Chuck Jaws (2).jpg
    Attached Images Attached Images

  2. #2
    Join Date
    Nov 2019
    Location
    Australia
    Age
    29
    Posts
    12

    Default

    Hi mate, I've been chasing some outside jaws for a old 3 jaw chuck on my hercus lathe and I think these might fit. Did you have the part number for these so I can cross reference them?

  3. #3
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    831

    Default

    I don't have the actual jaw part numbers, I got all the dimensions from this catalogue:

    Pratt Burnerd Chuck Data.pdf

  4. #4
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
    6,458

    Default

    Just wondering Lex,

    The outside jaw dimensions in the PB pdf for a 3" scroll chuck are the same as your 2.75" set. I have a 3" scroll chuck and the inside jaw dimensions are all slightly smaller than those listed. Same pitch though. Any chance of checking if your jaws are also undersize?

    Regards
    Bob.

    IMG_20201124_095950204 (1).jpg

  5. #5
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    831

    Default

    No worries Bob, I will check the sizes but I think they will be pretty close to what is shown. Which size jaw do you want me to measure?

  6. #6
    Join Date
    Nov 2008
    Location
    Perth WA
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    71
    Posts
    6,458

    Default

    The small set of jaws for the 2 3/4" chuck Lex. Thank you.

  7. #7
    Join Date
    Nov 2008
    Location
    Perth WA
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    71
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    Default

    Lex,

    To prevent you wasting time measuring the jaws, there's one dimension that's critical, the jaw width. My jaws are 0.370" wide. Anything wider won't fit the chuck's jaw slots.

    Bob.

  8. #8
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    831

    Default

    I'm glad that you asked me to measure these again Bob because I can now see that only the smaller set of jaws actually match up to anything on the chart, the .1875" Pitch ( 5.333 TPI) of the larger set is not standard according PDF.
    The small Jaws measure .368" wide.

    I also found another set with different dimensions: Length - 1.196", Height - 1.132", Width - .370", Tenon - .1875", TPI - 6

    They are the set in the middle of this photo:

    Pratt Jaws.jpg

  9. #9
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
    6,458

    Default

    Thanks for going to the trouble of measuring the jaws Lex. If you are prepared to post them to Perth I'll buy the small set. I'll send you a PM.

  10. #10
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    831

    Default

    Are you sure that the .368" will be OK, not too loose? What is your tenon size?

  11. #11
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
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    Default

    Lex,

    Two of my jaws are 0.368" the other, 0.370. I'll measure the tenon more accurately in the morning. The thickness in the tenon is critical.

    Bob.

  12. #12
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    831

    Default

    Yes, from your picture I thought it would be 3/16" not 1/8.

  13. #13
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
    6,458

    Default

    Lex,

    Photos for clarification. There is dimensional variation between the jaws and the thickest tenon 'web' is 0.210". The distance from the bottom of the jaw to the tenon is 0.180" and tenon width, 0.125".

    IMG_20211129_075234360.jpg IMG_20211129_074944029.jpg IMG_20211129_075025139.jpg

    I apologise for turning a simple sale into a saga. I have noticed that with my collection of PB chucks there isn't much in the way of jaw interchangeability. I have three 4" four jaw Pratt Burnerd chucks. Only a couple of the jaws interchange, the others bind.

    Bob.

  14. #14
    Join Date
    Nov 2008
    Location
    Perth WA
    Age
    71
    Posts
    6,458

    Default

    Lex,

    The jaws finally arrived today and were well worth the wait.....

    I just tried to send you a PM but your inbox is full.

    IMG_20211216_134846011.jpg IMG_20211216_135159950.jpg

    Bob.

  15. #15
    Join Date
    Jul 2009
    Location
    perth
    Posts
    67

    Default

    Hi Guys
    I am trying to source a set of inside jaws for the same size chuck as Bob's a 3" burned, if anyone has surplus
    Thanks Tom.

    Sent from my SM-G965F using Tapatalk

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