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Thread: Help with dies

  1. #1
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    Default Help with dies

    I am using a P and N M6 die to cut a thread at the end of what will be a special bolt. For some reason I struggle with dies. I use taps a lot and don't have any problems with them. For this bolt that I'm making the die rotates and chews up the work but doesn't leave a nice thread. I bought the die from a market but from memory it was still in a sealed container, the threads look new and sharp. I use Tap Magic and a small chamfer to help the die but am at a loss as to why my efforts with dies has been mixed to say the least. There's plenty of advice on taps but not much on dies. Any suggestions?

  2. #2
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    Is your Stock adjustable and does the Die have provision for adjustment.
    You use the Die the same as you would a Tap,1 1/2 to 2 turns reverse to break the swarf and go again.
    The Pitch of the M6 is only fine so you may have to remove the Stock and Die from the job and clean the Swarf.
    What material are you cutting.

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    Having seen high school students in action with dies,I am pretty much aware of most of the mistakes that can be made.

    As Pipeclay has mentioned ,swarf breaking adjustment and cleaning as possible causes.
    Some other causes can be be:
    • Rod diameter size a tad larger than spec
    • Button die and handle not squarely aligned to the bolt shaft.
    • There are guides made to align the handle and die to the shaft to be threaded, but most of us go by alignment by eye.


    Metric has a fine and coarse pitch as well and this will add to he problem if one of the other causes applies.

    Attached pic is an Irwin brand adjustable die button holder with guides

    Hope this helps
    Grahame

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    Could be crappy metal in the bolt..

  5. #5
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    I am unsure of what you are doing here.
    Are you extending the thread on an existing bolt, or are you making one up from scratch.

    RC may have hit the nail on the head.
    Some mild steel, as in rod for fabrication tears when machined,so it follows the same may occurr when cutting a thread with your die.

    A better grade of steel for for threaded bolt may well fix the problem if 'as above' does not apply.

  6. #6
    BobL is online now Member: Blue and white apron brigade
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    Assuming everything else is OK, a cheats way out (espec when dealing with difficult material) is to make the bolt about 12- 25 mm longer than required and put a longer more gradual chamfer onto the end. Then the die can more easily creep up to the right diameter, then cut or turn the excess length off.

  7. #7
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    Thanks guys for your thoughts. This morning I decided to make a longer chamfer, that helped as I was struggling to get the die started, it just kept turning on the workpiece.
    The other thing that was happening was that despite trying the 3 die holders that I have, the die was rotating instead of biting into the work. I am trying to make a special bolt, it is a mild steel that machines and drills easily enough. The long chamfer really helps, do others here use long chamfers, if so, how long?

    I remember seeing a shop made threading device that had a knurled outside. The instructor turned the lathe on and gripped the knurled surface. In a matter of seconds the thread was formed. This lathe had backgears and so very slow speeds were used. As I've had so many problems with dies and I will need to make more male threads soon, I would like to make one of these threading devices, anyone have a link to how they are made/used? For that matter, would appreciate any devices that assist with die threading.

  8. #8
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    Tiger ,
    Is this what you mean?

    I have made myself a die holder that fits in the tail stock chuck.
    The die fits into a hollow machined for it in the face and it is prevented from turning with the thumbscrew fitting into a divot hole on the circumference of the die,

    The lathe is not switched on but alternately the chuck is puled over by hand .
    The die cuts its way up the bolt.
    Movement allowance comes via the sleeve over the saht into the tail stock chuck.

    The device is purely to keep the die square to the shank of the bolt.
    The arm rests on the cross slide and prevents the die holder from rotating.

    Grahame

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    You are starting it off in the correct side of the die aren't you? Usually the writing on the die is facing you whilst the bolt starts on the other side which is tapered in.

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    Quote Originally Posted by Tiger View Post
    Thanks guys for your thoughts. This morning I decided to make a longer chamfer, that helped as I was struggling to get the die started, it just kept turning on the workpiece.
    The other thing that was happening was that despite trying the 3 die holders that I have, the die was rotating instead of biting into the work. I am trying to make a special bolt, it is a mild steel that machines and drills easily enough. The long chamfer really helps, do others here use long chamfers, if so, how long?

    I remember seeing a shop made threading device that had a knurled outside. The instructor turned the lathe on and gripped the knurled surface. In a matter of seconds the thread was formed. This lathe had backgears and so very slow speeds were used. As I've had so many problems with dies and I will need to make more male threads soon, I would like to make one of these threading devices, anyone have a link to how they are made/used? For that matter, would appreciate any devices that assist with die threading.
    Once again would be HANDY if all the information was GIVEN in your original question.
    Long leads on your rod are not a problem.
    What sort of STOCK are you using.
    Why dont you cut these threads on your lathe.
    What make of die are you using.

  11. #11
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    Quote Originally Posted by pipeclay View Post
    Once again would be HANDY if all the information was GIVEN in your original question.
    Long leads on your rod are not a problem.
    What sort of STOCK are you using.
    Why dont you cut these threads on your lathe.
    What make of die are you using.
    I don't think some of these are relevant. Not sure what you mean by long lead.
    The Stock is your normal circular recessed die holder with 2 handles. Why am I not cutting threads on the lathe? Lowest speed is 100 rpm, it takes a fair bit of skill to get this to work not to mention changing the gear train, all for just one type of thread, easier to use a die. The make of die was mentioned in the original post, P & N.

  12. #12
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    Lead similar to Chamfer.
    Is your Stock adjustable.
    Be good threading practice on the lathe.

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    Quote Originally Posted by Tiger View Post
    I don't think some of these are relevant. Not sure what you mean by long lead.
    The Stock is your normal circular recessed die holder with 2 handles. Why am I not cutting threads on the lathe? Lowest speed is 100 rpm, it takes a fair bit of skill to get this to work not to mention changing the gear train, all for just one type of thread, easier to use a die. The make of die was mentioned in the original post, P & N.

    100 rpm is is not too fast for screw cutting .

    That's why they are called change gears ,they are supposed to be changed so you can cut different threads,whether you are cutting one thread or ten .
    A good machinist can cut a thread to get a better fitting thread than you'll ever get with a die.
    Just takes practice ,and you won't get it by using a die .

    If your die is a split die then its adjustable ,your die stock should have three or four thumb screws ,the die will have two dimples and a taper on the edge of where its split .
    The middle screw on the die stock should go into the split ,and two other screws should line up with the two dimples on the die.
    You can spread the die by loosening the the two dimple screws and screw in the the middle one until the die is tight in the holder .
    Thread the rod at this setting , run the die back off the thread and loosen the middle screw and tighten the two out ones a little ,run the die down the thread again .
    Use a good lubricant like Tap magic , or trefolex.
    Turn the die half a turn and then back off a bit , this breaks the chip at the cutting edge .

    Try a nut on the rod , if its still too tight , tighten the two outer screws on the die stock and back off the middle one again a little bit at a time.Run the die down the thread again , try the nut .keep doing this until the nut is a good fit on the thread.
    A lot of pizzling around , much quicker to screw cut the thread on the lathe .

    Kev.
    "Outside of a dog a book is man's best friend ,inside a dog it's too dark to read"
    Groucho Marx

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    Hi, I'm just a noob but can anyone give me a list of turned sizes for stock in metric sizes?

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    Quote Originally Posted by Trewella View Post
    Hi, I'm just a noob but can anyone give me a list of turned sizes for stock in metric sizes?
    Trewella,

    Theres far too many types and sizes to list here,
    have a look here

    http://www.atlasmetals.com.au/files/...ual%202008.pdf


    Grahame

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