Results 1 to 8 of 8
  1. #1
    Join Date
    Aug 2015
    Location
    Melbourne, Australia
    Posts
    843

    Default metric Uk bridgeport - acme or trap leadscrews?

    Hi all,

    Just doing a cleanup and inspection on a 1981 UK metric BP. Screws are not tooo bad but nuts are not very good.

    Anyone know if the leadscrews on a metric BP are 29deg acme form or 30deg trapezoidal form?

    Many thanks,

    Greg.

  2. #2
    Join Date
    Feb 2013
    Location
    Laidley, SE Qld
    Posts
    1,038

    Default

    No idea as to metric or imperial, but if you measure the pitch over 10 or more threads that should enable you to tell what variety you are dealing with.

  3. #3
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    Sorry bob, how would measuring the pitch tell you the flank angle, I think the issue is He doesnt know what the flank angle is.

  4. #4
    Join Date
    Feb 2013
    Location
    Laidley, SE Qld
    Posts
    1,038

    Default

    Metric has 30 degree flanks imperial has 29 degree.

  5. #5
    Join Date
    Aug 2015
    Location
    Melbourne, Australia
    Posts
    843

    Default

    Thanks Bob, I do know the pitch. It is 5mm vs the 5 tpi of an imperial BP. It is not a given that because it is a metric pitch it has a 30 degree angle. It could be a 5mm pitch cut using the 29deg acme form. I also asked this over on PM and a fellow from the UK says he measured it and it was 29, not 30. The reason I ask is that, depending of what else need fixing on this BP I may or may not have the budget to buy new nuts. I guess this is some research into 'if I made them myself ... etc'.

  6. #6
    Join Date
    May 2011
    Location
    Castlemaine
    Posts
    244

    Default

    Greg,

    If you have the screws out of the mill you are welcome to use my Optical Comparitor to check the thread angle.

    Cheers Piers

  7. #7
    Join Date
    Aug 2015
    Location
    Melbourne, Australia
    Posts
    843

    Default

    How can I say no to that! Thank Piers that would be amazing. I do have the screws out. I'll PM you.

  8. #8
    Join Date
    Aug 2015
    Location
    Melbourne, Australia
    Posts
    843

    Default the "big reveal" ... the winner is:

    First, a big thank you to Piers for spending time with me on his awesome optical comparator trying to discern 0.5deg on a worn leadscrew. Not easy. Although not conclusive, we felt it was more likely ACME than trap.

    Thanks Piers, it was a great experience and I learned stuff. I owe you one.

    BUT .... I contacted Hardinge .. who contacted their "UK friends" to see if we could get an answer. It took a couple of weeks of emails .. but ... dignitaries, ladies and gentlemen, boy and girls. It is ACME. Here is a snippet of their manufacturing spec.

    leadscrew_spec.jpg

    case closed. )

    Greg.

    Thanks again Piers.

Similar Threads

  1. Acme LH 7/8" x 4 tpi nut
    By bob ward in forum METALWORK GENERAL
    Replies: 9
    Last Post: 14th Oct 2015, 11:47 AM
  2. Replies: 8
    Last Post: 1st Sep 2014, 12:26 PM
  3. 3/8-12 acme tap
    By rusel in forum METALWORK GENERAL
    Replies: 5
    Last Post: 23rd Mar 2012, 02:39 PM
  4. ACME 1/2 - 8 LH rod available ?
    By morrisman in forum METALWORK GENERAL
    Replies: 32
    Last Post: 1st Dec 2011, 10:22 AM

Posting Permissions

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