Need help with Bspt thread
Close
Login to Your Account
Results 1 to 9 of 9
  1. #1
    Join Date
    Apr 2020
    Country
    UNITED KINGDOM
    Posts
    5
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default Need help with Bspt thread

    Hi ,
    Im looking for the starting size and finishing size for 1/2 bspt threads external...
    we are running a rlx protrak 1630, trying to get the thread sizes correct in custom threads but its not working..
    does anyone have the correct sizing for the starting point..
    major dia is 20.955, minor dia is 18.633, pitch 1.814, were cutting the correct pitch but the thread isnt correct in height etc, trying on a new fittings and not working..
    cutting en3b bar...but we have pb bronze to machine shortly...
    any help on sizing would be most appricated
    thanks
    Chris

  2. #2
    Join Date
    Jun 2012
    Location
    Michigan
    Posts
    5,987
    Post Thanks / Like
    Likes (Given)
    5642
    Likes (Received)
    3813

    Default

    Quote Originally Posted by smithy1851 View Post
    Hi ,
    Im looking for the starting size and finishing size for 1/2 bspt threads external...
    we are running a rlx protrak 1630, trying to get the thread sizes correct in custom threads but its not working..
    does anyone have the correct sizing for the starting point..
    major dia is 20.955, minor dia is 18.633, pitch 1.814, were cutting the correct pitch but the thread isnt correct in height etc, trying on a new fittings and not working..
    cutting en3b bar...but we have pb bronze to machine shortly...
    any help on sizing would be most appricated
    thanks
    Chris
    Your numbers are spot on.What insert are you using? Is it sharp enough?
    Are you cutting a right hand thread?

  3. #3
    Join Date
    Mar 2008
    Location
    vacaville ca
    Posts
    569
    Post Thanks / Like
    Likes (Given)
    90
    Likes (Received)
    151

    Default

    also using 55deg cutter?

  4. #4
    Join Date
    Apr 2020
    Country
    UNITED KINGDOM
    Posts
    5
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default

    Hi
    Yes cutting righthand thread, new 14tpi insert, vardex, brand new only cut these threads, nice and sharp point...
    55' angle, coming in at 27 degrees to make sure insert is cutting on leading edge...
    its just not working and cant see why not...!!

  5. #5
    Join Date
    Dec 2011
    Country
    UNITED STATES
    State/Province
    Illinois
    Posts
    407
    Post Thanks / Like
    Likes (Given)
    93
    Likes (Received)
    127

    Default

    Are you figuring your taper correctly? It should be 3/4" taper per foot, if I'm not mistaken.

  6. #6
    Join Date
    Sep 2010
    Location
    india
    Posts
    1,376
    Post Thanks / Like
    Likes (Given)
    75
    Likes (Received)
    263

  7. Likes Mtndew liked this post
  8. #7
    Join Date
    Jul 2007
    Country
    UNITED KINGDOM
    Posts
    5,471
    Post Thanks / Like
    Likes (Given)
    3424
    Likes (Received)
    2820

    Default

    Is it a full form insert?

  9. #8
    Join Date
    Apr 2020
    Country
    UNITED KINGDOM
    Posts
    5
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Default

    Hi
    sorry for delayed reply.....

    its a Vardex size 3, single point insert ...ive re calculated everything and its still far too tight,
    whats strange too is that the pitch is correct when checked with a thread gauge...
    im now wondering if the insert if wrong..
    having to dig out the coventry die box with chasers to get the job sorted..

  10. #9
    Join Date
    Sep 2010
    Location
    india
    Posts
    1,376
    Post Thanks / Like
    Likes (Given)
    75
    Likes (Received)
    263

    Default

    Starting with a slightly lower OD may help.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •