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  1. #1
    Join Date
    Apr 2009
    Location
    Kingswood
    Posts
    930

    Default Flange Nuts Jamming on Clamp Studs

    An interesting observation, and a request for comments and/or suggestions.

    I have a standard M8 clamp set for my benchtop mill (Emco FB2 clone).
    To increase the range of sets, I have made several studs out of common M8 studding.

    The regular flange nuts jam on the studding, but not on the regular studs from the set.
    The jamming occurs on the pull-down, the studding always comes out of the T-nut when the flange nut is turned with the spanner.
    The flange nut is jammed so tight that the nut cannot be moved by holding the studding in the hand ( my weak hands with coolant etc), but it is easy with a spanner.
    (I screw the studding into a T-nut in the mill table and applying a spanner in the tightening direction)

    The studding is 7.8 mm OD, the regular studs 7.6 mm OD.
    Visually, the studding can be seen to have a much sharper V crest on the thread, compared to a pronounced flat crest on the regular stud.
    The flange nut 'feels' just as loose on either the studding or the regular studs.

    Should I just take the 0.2 mm off the diameter and see how it goes ?

    Anyone else notice this problem ?

    John.

  2. #2
    Dave J Guest

    Default

    Hi John,
    I noticed a few weeks ago using the flange nuts from my M12 set on some hardware store zinc plated thread that it jammed up as well. I was using it under pressure pressing something in, but put down to weak threads as I could see it had deformed the thread rod. Maybe try some high tensile thread rod instead.

    Dave

  3. #3
    Join Date
    Oct 2008
    Location
    blackburn vic
    Posts
    297

    Default Allthread studs

    Had a similar problem fixed mostly by running a die down the thread and cleaning off high spots on the plating. I dont use my "extra" studs much until I get hold of some better steel.

    Roger

  4. #4
    Join Date
    Jun 2008
    Location
    Lindenow
    Age
    50
    Posts
    869

    Default

    Yup running a die down the threaded rod to remove the gal coating. It worked for me anyways..
    Warning Disclaimer

  5. #5
    Join Date
    Apr 2009
    Location
    Kingswood
    Posts
    930

    Default

    My studding is the zinc plated type.

    I have run a die along a pice of studding and then clamped a test job with the bar flat to avoid twist in the flange nut.
    No difference, still jammed, but perhaps less tightly.

    A look around found local sources for Grade 8.8 and 10.9 black studding.
    The price I saw for M8 was a pack of 20 x 1m lengths for $450 !

    Anyone able to advise an alternative source ?

    John.

  6. #6
    Dave J Guest

    Default

    Hi John,
    I found this place last year, but M8 still seems expensive compared to the larger sizes. It might be worth giving them an email to see.
    https://www.bolt.com.au/high-tensile...1834_1835.html

    Dave

  7. #7
    Join Date
    Jun 2008
    Location
    Lindenow
    Age
    50
    Posts
    869

    Default

    Just a brain fart here,
    Could buy some high tensile or spring steel rod and screw cut it on the lathe, I would think it much cheaper than buying pre-threaded.
    Just a thought
    Matt
    Warning Disclaimer

  8. #8
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
    Posts
    4,887

    Default

    If your clamping set is Chinese that will be a big part of your problem.

    If you have allready sourced your threaded rod locally for your studs I would suggest to also purchase enough flange nuts to suit your needs.

    From my experience over the years the chinese variety of threads are very different from the standard type,even there head sizes or what ever method of tightening they use is correct in name only,for some reason they dont make to standard,they make to what either looks close or works for them.

    I would not try and interchange Chinese fasteners with any industry standard fastner,your just looking for trouble.

  9. #9
    Join Date
    Jun 2008
    Location
    Victoria, Australia
    Age
    74
    Posts
    5,080

    Default

    Quote Originally Posted by electrosteam View Post
    My studding is the zinc plated type.

    I have run a die along a pice of studding and then clamped a test job with the bar flat to avoid twist in the flange nut.
    No difference, still jammed, but perhaps less tightly.

    A look around found local sources for Grade 8.8 and 10.9 black studding.
    The price I saw for M8 was a pack of 20 x 1m lengths for $450 !

    Anyone able to advise an alternative source ?

    John.
    Hi John,

    If you are having trouble getting M8 allthread....

    What about buying some M8 full threaded bolts, longer than you need and cut off some of the thread portion, to suit the length for the clamp studs. If you plan it right, you might be able to use the remaining part, the shorter bolts, for another job.

    I think M8x50's (grade 8.8) should cost less than 50 cents each. Just make sure that you ask for full-threaded, not half threaded.

    Regards
    Ray

  10. #10
    Dave J Guest

    Default

    Hi Ray,
    They call those type of bolts are called set screws,
    https://www.bolt.com.au/high-tensile...page=2&sort=3a

    I remember learning that years ago at Mulling fasteners when I asked for some set screws, and the bloke came up with bolts instead of the grub screws I was after.
    Dave

  11. #11
    Join Date
    Apr 2009
    Location
    Kingswood
    Posts
    930

    Default

    Just tried a flange nut against a standard nut on a bar, tightened up with 150 mm spanners, then released without restraining the bar.

    The studding and fixings were purchased in small quantities at a local industry supplier in Penrith.
    The clamp set was acquired from a machinery merchant in Sydney a few years ago, probably Chinese.

    Results to date, including the original comments:
    - Chinese stud 7.6 OD black - no jamming,
    - local studding 7.8 OD Zn plated - flange nut jammed,
    - local studding 7.8 OD Zn plated cleaned with die - flange nut jammed,
    - grade 8.8 set screw 7.8 OD passivated (yellowish) - flange nut jammed,
    - cap screw 7.7 OD black - no jamming.

    The setscrew passivation could be some sort of Zn product.

    The results above do not differentiate between OD size and Zn, need more data.
    Can anybody add some data ?

    Or, as Pipeclay suggests, it is bad thread shape.

    The suggestions on alternative sources for studs will be followed up.

    John.

  12. #12
    Join Date
    Oct 2008
    Location
    blackburn vic
    Posts
    297

    Default Threaded Studs

    The studs that I made were just allthread from Bunnings and after cleaning up worked OK. Maybe I fluked it.
    I have been told that Ferntree Gully Bolts sell High Tensile allthread but I havent checked it out yet.

    Roger

  13. #13
    Join Date
    Apr 2009
    Location
    Kingswood
    Posts
    930

    Default

    Roger,
    Since you reported good results, I thought I should investigate further.

    My clamp set came in the usual holder with 6 flange nuts.
    I tested all the nuts on some Zn M8 studs (not the original black studs).
    3 would jam and 3 would not, so perhaps we could say the problem aflicts 50% of the nuts.

    I set up the lathe with a M8 mandrel and proceeded to clean up all the Zn studs.
    First some emery to get any high spots off.
    Then a die held in the fingers as the lathe was operated (58 RPM) forward with the die pushed against the side of the thread, and then in reverse with the die pulled against the thread.
    The appearance is much better, clean and bright.

    When tested, 2 of the faulty nuts would still jam, but with much less tenacity.
    The jam was firm against a light twist with the fingers, but instantly released with minimal movement when a small spanner torque was applied.

    I inspected the nuts, but I could not clearly see any differences.
    All the nuts have poor shape on the unloaded side (lower) when clamped on a stud in the mill.
    The thread flank taking the thrust (upper) are all smooth and bright, but could be worn.

    My hypothesis is that the problem is likely to be a small imperfection in the nut thread that "welds" to the Zn coating on the stud.

    Whatever, the effect is much reduced on the clean studs, and the cost of black hard studs is not worth the improvement.

    John.

  14. #14
    Join Date
    Jul 2003
    Location
    The Fabulous Gold-plated Coast.
    Age
    69
    Posts
    2,251

    Default

    Just to throw another spanner in to the works, I purchased some threaded rod recently that turned out to be Whitworth 55º thread form. Perhaps?

    Greg

  15. #15
    Join Date
    Oct 2008
    Location
    blackburn vic
    Posts
    297

    Default Threaded Studs

    I suppose I should have stated that my clamp set is 3/8 whit and are about 20 years old. It doesnt affect the original studs but maybe my flange nuts are suitably worn. I only made the studs to complement the kit that I have.

    Roger

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