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Thread: Adjustable / Split Die Question

  1. #1
    Join Date
    Aug 2009
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    6,595

    Default Adjustable / Split Die Question

    Well my first mistake was to assume that the position of the two set screw pockets in an adjustable die was an industry standard.
    All my dies were always hex. I never messed around with the round dies until I made my two little special die holders for threading my custom U-bolts.
    The first two split dies I bought were made by Widell. The two set screw pockets are on the center line of the die positioned 90 degrees from the slit and 180 degrees apart.
    So when I made my die holders I put the set screws in that respective position. Having a set of Rigid bolt dies which also use a split die with the set screw pockets on the center line 90 degrees with the split I figured that this was the industry standard for this type of die.
    When I saw Brian's post the other day where the locking screws on his die handle were so close to the slit I began to wonder.

    Now that I messed up the only two good 5/16"-18 HSS dies I had threading that crappy 304 ss I had to buy a different brand. I found some OSG ones.
    Today when I got the dies and went to put one in the holder I noticed that the set screw pockets were in a different position. So now the only thing holding the die from slipping is the pointed set screw in the slit. The other set screws seat against the smooth side of the die and I doubt that they offer any holding force.
    Fortunately the die cuts the 303 ss like butter so the pointed set screw is holding it pretty well, I still don't like it but......
    Just out of curiosity if I decided to make a pocket what would be the best way to go about it?? Can't drill it, I doubt that a carbide ball end mill would touch it either.
    I was just thinking about that 400,000 RPM dental grinder that Edwin posted. I was pretty impressed when he cut that hole through the tap. If it can do that it can grind out a pocket with the appropriate stone or bit.
    Perhaps that and some diamond bits. I have a Dremel tool with some conical stones but I don't think that will do it.
    Any thoughts?



    JL.....................

  2. #2
    Join Date
    Jun 2019
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    102

    Default

    Quote Originally Posted by JoeLee View Post



    JL.....................
    Round split adjustable dies are exactly as they are described, round and adjustable.

    There is a screw that keeps the slot from closing to far, there will be a provision for a setscrew or 2 about 90 Deg. from the slot, this closes the die on the setting screw, do not put a pointed set screw near or on the slot.

    Such dies are adjusted by threading a test specimen and measuring the Pitch Diameter then adjusting the die diameter as required using the stop screw. On the very rare occasion that I use a threading die I will go into the drawers where such dies are kept, often each box that they ship in has "Die Not Set" written on it with a Sharpie pen. This means that the last person to use it did not set it.

    The adjustment does have advantages beyond thread accuracy however, you may use 2 dies, one for roughing and one for finishing on difficult materials such as Inconel, open the roughing die with the stop screw until it makes a partial thread then finish with the finish die to size, works a charm but is slow as you may imagine.

  3. #3
    Join Date
    May 2002
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    SE Texas
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    12,482

    Default

    I have never seen the problem you describe, but what do I know. I haven't purchased a threading die in over ten years.

    I would try using an abrasive burr in the Dremel. That would surely cut it. A small spherical one to start and then, perhaps one with a point to finish up with a better fit for the set screws.
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

  4. #4
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    Oct 2013
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    USA MD 21030
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    Default

    I can't see that tiny image (thumbnail?). So I clicked on it and dragged the image here:


  5. #5
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    Aug 2002
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    I have been wondering about that die stock that Brian made also. ALL the die stocks I've ever seen the locking set screws have been 3 at 90 deg separation. All the adjustable dies have I've seen used a screw IN the die. All this stuff about a V point for in the adjust slot doesn't make sense since the screw in the die isn't going to allow a pointey screw to do anything anyway. This covers a dozen or more die stocks at school and the couple I have at home
    ...lew....

  6. #6
    Join Date
    Aug 2012
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    Warwickshire, UK
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    Default

    The other way round for me.I must have about 100 split dies of various sizes and thread forms, and only one of them has the adjusting screw IN
    the die. All the rest I have and really. have ever seen, have a vee form split in the die, and rely on a pointed screw in the holder to adjust the size, with 2 screws at 45 degrees on either side of the adjusting screw for location.
    'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

  7. #7
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    Aug 2009
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    Quote Originally Posted by PStechPaul View Post
    I can't see that tiny image (thumbnail?). So I clicked on it and dragged the image here:

    My images used to show up full size like that when I used Dump Bucket, but I don't know how to get them full size for forum posts now that I'm using Post Image. Org for hosting.
    I can click on the image on the hosting site and get a full size pic but when I post the link here all that shows up is a small pic.

    JL...............

  8. #8
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    Dec 2015
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    Chilliwack, BC, Canada
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    I've got a number of split dies. Some have the spreading screw in the die and others do not. I'd say it's about a 50-50 split..... sorry There does not seem to be any rhyme or reason to brands that have a screw and those that rely on the screws in the holder. If there is a trend it seems to be one where the smaller sizes that are split use a screw while the larger sizes seem to be split with no screw.

    Only the dies that do not use a screw have the clamping notches set at about 45* to either side of the split. The ones with screws of some sort all have a single divot 180 around from the split for the retaining screw.

  9. #9
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    Mar 2015
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    Central Ms
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    Quote Originally Posted by JoeLee View Post
    My images used to show up full size like that when I used Dump Bucket, but I don't know how to get them full size for forum posts now that I'm using Post Image. Org for hosting.
    I can click on the image on the hosting site and get a full size pic but when I post the link here all that shows up is a small pic.

    JL...............
    When the PB fiasco happened I started using this site's photo posting feature. Works great for me with no sizing issues.
    “I know lots of people who are educated far beyond their intelligence”

    Lewis Grizzard

  10. #10
    Join Date
    May 2015
    Location
    Somerset UK
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    Default

    If I have to use a split die, I always open it up as wide as the diestock will allow for the first cut, then reduce subsequent cuts until the nut to be used with it fits nicely. I prefer single pointing with carbide unless there is no alternative.

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