cutting M5 thread on 5mm steel rod - thread loose

Discussion in 'Engineers' Talk' started by Don4, May 24, 2009.

  1. Don4

    Don4 New Member

    Gratefull for any help here. I'm not that experienced with engineering.

    I'm making a truss rod for an electric guitar. The rod is 5mm thick and requires threading at one end so that when installed a nut can be turned against a bearing plate to tension the neck.

    I have so far gone through 4 pieces of steel rod cutting the thread with an M5 0.8 die out of a Screwfix branded set I bought.

    The nuts are a bit loose on all of them and the thread strips off under even a little tension.

    Advice would be greatly appreciated!
     
  2. chippie244

    chippie244 Super Member

    How long does the rod need to be?

    A decent die should have an adjuster so you can tweak the exact diameter it's cutting.
     
  3. G Brown

    G Brown New Member

  4. DewaltÆ User

    DewaltÆ User New Member

    you cant cut a M5 thread on M5 Bar, it cant be done the rod is too small in diameter, you would have to thread it M4 for it to work.
     
  5. Don4

    Don4 New Member

    Thanks for the link G Brown but I'm making a non-standard scale length neck.
     
  6. Don4

    Don4 New Member

    Yeah I can see the screw Chippie but it doesn't seem to do much. Also when I look inside the die there seem to be a couple of small bits that have broken off.
     
  7. Don4

    Don4 New Member

    On a tea-break, are you sure about this? becuase the manual says that it is what you should do and it sure does cut a thread it's just a bit loose.

    I have also used an M10 die to extend the thread on M10 coach bolts with no problem.
     
  8. Don4

    Don4 New Member

    I think I'm going to tr a new die.
     
  9. ponty01.

    ponty01. New Member

    You DO use 5mm rod for an M5 thread.

    If your die holder has 3 screws to locate the die then you only use the middle screw initially. You tighten this screw onto the die where it is split. This opens the die up. If the thread is too large you then loosen off the centre screw and tighten the outer screws instead. Dont over tighten them, you can always tighten them a bit more if the nut is still not fitting.

    When cutting the thread keep the die lubricated with oil, once you have got the first couple of threads cut you then turn the die 1/2 a turn and then back 1/4 turn, and continue with a 1/2 a turn to cut and back 1/4 turn until the thread is cut. This stops the die clogging up and damaging the thread. keep lubricated throughout.

    Job done!
     
  10. Don4

    Don4 New Member

    Thanks Ponty, the info about the position of the holder relative to the die is the bit I was missing.

    Cheers
     
  11. jasonb

    jasonb New Member

    Ponty has just about covered it. Couple of other things

    Put a small chamfer on teh end of the rod, this will help teh die to start.

    The side of the die with the size writen on it should be the side that goes onto the rod first as it has a slight lead.

    Jason
     
  12. Don4

    Don4 New Member

    Thanks Jason;
    So totting up the points in the advice above I get-- Now let me see.....

    Yep I was doing everything wrong.

    Time to try again. And this time I aint putting the rod in the neck and gluing the fillet over the top of it until the thread is solid.

    Thanks guys for the help.

    Don
     
  13. malkie129

    malkie129 Screwfix Select

    Ponty & Jason are dead right. The only thing that I would add, is that to get the thread square, you should cut it in a drilling machine. Place your 5mm rod vertically in a drill vice, place the die & stock on the chamfer & then gentley lower the drill/chuck onto it.Keeping a light pressure on the die & stock, then cut your thread as previously described. Sorry if this is not too clear, but it is easier to show than describe. Any probs, then please come back. HTH malkie.
     
  14. Don4

    Don4 New Member

    Thanks Malkie.

    OK, I have followed the procedures here and I have acquired a die holder with three screws and M5 0.8 split die.

    I have tightened the one screw to open the die up as much as I can. I have got it the right way up (writing facing down) and have followed the described procedure and thanks to you it is a LOT better but it still isn't snug. These are standard M5 hex nuts I'm trying on the thread and I would have thought I could get it so there is virtually no play when you try and wiggle the nut on the thread.

    Maybe I'm expecting too much.

    Don
     
  15. andc1

    andc1 New Member

    This is one area where quality counts get a quality die.
     
  16. malkie129

    malkie129 Screwfix Select

    No Don, you're not expecting too much...I'm just trying to think what is wrong !!! Have you got the right size die stock? Even with Metric threads,some dies are Imperial O/D (15/16). Is it a decent die (SKF/Dormer)? Come on blokes..Help out...I'm thinking after 6 pints of Grolsch
     
  17. Don4

    Don4 New Member

    Thanks guys. I'm suspecting die quality. One screwfix, one halfords.

    What would you recommend?

    (Jealous about the Grolsch now)

    :eek:)
     
  18. Don4

    Don4 New Member

    Sorry, you already said Dormer / SKF
     
  19. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    No-one has mentioned the thread gauge, which I would presume may be as important as the overall size!!!!!


    Mr. HandyAndy - Really
     
  20. oliver1234

    oliver1234 New Member

    Mr. HandyAndy - Really

    Isn't M5 the gauge, ie, 5mm?

    The pitch will be .8
     

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