Where to find 1/4-24 and 5/16-20 bolts?
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    Default Where to find 1/4-24 and 5/16-20 bolts?

    Antique sizes, so I'm told. Not sure if they're still made anywhere on planet Earth except for a few specialty Harley shops, and then only in the one or two lengths used by pre-war Harleys. Does anyone know a source for these odd threads? And no, they are not mis-identified metric threads. These are the real thing, square heads and all.

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    Quote Originally Posted by borne2fly View Post
    Antique sizes, so I'm told. Not sure if they're still made anywhere on planet Earth except for a few specialty Harley shops, and then only in the one or two lengths used by pre-war Harleys. Does anyone know a source for these odd threads? And no, they are not mis-identified metric threads. These are the real thing, square heads and all.
    You can still make - or buy - taps and dies for 'em:

    National Supply Source Thread Monster Solid Carbide Thread Mills - 60º UN Thread - TiN Coated* - Thread Monster Solid Carbide Thread Mills - 60º UN Thread - TiN Coated* Product Page

    But 'the usual suspects' don't seem to stock 'em.

    Bill

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    I think you're going to need one of those places - what are they called ?... oh yeah a machine shop

    There is tap & die company in the US that does the oddball sizes but I can't recall their name.

    Only few req'd ? - single point them.

    Up to a few hundred - get a split solid die.

    Few hundred plus - get a set of dies made for a geometric die box.

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    Quote Originally Posted by Limy Sami View Post
    I think you're going to need one of those places - what are they called ?... oh yeah a machine shop

    There is tap & die company in the US that does the oddball sizes but I can't recall their name.

    Only few req'd ? - single point them.

    Up to a few hundred - get a split solid die.

    Few hundred plus - get a set of dies made for a geometric die box.
    So long as the material to be threaded is mild steel OE, making one's own taps and dies is not at all difficult...

    If no screw-cutting lathe with appropriate settings, buy one tap, make the die(s) with that.

    Both sizes are small enough to heat-treat tap OR die with a torch.

    Bill

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    Parts like that fall off my lathe occasionally, but the time to make them means they are not cheap.

    You can buy the taps and dies for reasonable prices here: High Speed Round Adjustable Dies - special thread up to 1/2".

    Larry

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    Thanks Larry - that was the firm I was thinking of.

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    Quote Originally Posted by borne2fly View Post
    Antique sizes, so I'm told. Not sure if they're still made anywhere on planet Earth except for a few specialty Harley shops, and then only in the one or two lengths used by pre-war Harleys. Does anyone know a source for these odd threads? And no, they are not mis-identified metric threads. These are the real thing, square heads and all.
    This is one of the threads (I'm referring to the post ) I don't get.

    A bolt isn't just a bolt. Are you intending using it for a Harley or not?
    Quantity, length, steel quality? Must it have a square head? Are you able to make it yourself if need be?

    Think how easy it would be for you to give just a bit more info.

    I looked in my ASME B1.1 and found that 1/4"-24 is between UNC and UNF but not included in the standard. On the other hand 5/16"-20 is specified as UN.

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    Default Harley bolts

    You may want to check the thread form as well. Are they 60 degree UN or 55 degree Whitworth?

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    I have both a ¼-24 and 5/16-20 tap that are yours for the asking.
    If for nothing else you can use them to chase threaded holes.
    PM me if interested.

    Joe

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    Quote Originally Posted by Leadfootin View Post
    You may want to check the thread form as well. Are they 60 degree UN or 55 degree Whitworth?
    That certainly is a valid point but the two threads given are neither BSW or BSF so I'm guessing they aren't Whitworth

    I still don't know if the mention of Harley was intended as helpful or just very misleading.
    If the mention of Harley was meant to be helpful then it'd been better to mention it in the title. That'd attract many more members LOL

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    drill and put a helicoil or whatever you prefer in there for modern bolts. for the 5/16 you might even get away with just chasing with an M8 tap, depends on the thread depth i guess. M7 might work for the smaller one but i don't think that really exists in the real world...

    but then as Gordon said, without knowing your intended use the above may as well be totally useless...

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    Quote Originally Posted by Joe21 View Post
    I have both a ¼-24 and 5/16-20 tap that are yours for the asking.
    If for nothing else you can use them to chase threaded holes.
    PM me if interested.

    Joe
    That surely must be one of the major things as to what PM is about. Joe, I hope others are as helpful to you

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    Joe21 .... PM sent

    Sorry folks, the only reason I mentioned Harley was that it's one of the few things I could remember that used these fasteners. My application is for toolholders on a turret, and the existing bolts appear to be just mild steel. Yes, I could single point them, but first I thought I'd check if anyone still cranked them out by the truckload, in which case it would make more sense to just buy a bunch. I haven't reached the point yet where I'm too cheap to buy nuts & bolts But I guess these really are rare as hens teeth so I'll just hammer 'em out myself.

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    Quote Originally Posted by borne2fly View Post
    Joe21 .... PM sent

    Sorry folks, the only reason I mentioned Harley was that it's one of the few things I could remember that used these fasteners. My application is for toolholders on a turret, and the existing bolts appear to be just mild steel. Yes, I could single point them, but first I thought I'd check if anyone still cranked them out by the truckload, in which case it would make more sense to just buy a bunch. I haven't reached the point yet where I'm too cheap to buy nuts & bolts But I guess these really are rare as hens teeth so I'll just hammer 'em out myself.
    The good news is that you can make 'em of better steel / heat-treat, and with your choice of tip form and driving head style.

    Bill

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    That's true, I'm free to make better ones. Ideally I'd like to make them all Allen heads but I don't have a rotary broach, at least not yet. Dear Santa ......

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    Quote Originally Posted by borne2fly View Post
    Joe21 .... PM sent

    Sorry folks, the only reason I mentioned Harley was that it's one of the few things I could remember that used these fasteners. My application is for toolholders on a turret, and the existing bolts appear to be just mild steel. Yes, I could single point them, but first I thought I'd check if anyone still cranked them out by the truckload, in which case it would make more sense to just buy a bunch. I haven't reached the point yet where I'm too cheap to buy nuts & bolts But I guess these really are rare as hens teeth so I'll just hammer 'em out myself.
    How hard are the tool holders? Do you have room to drill them out and tap them to a source able thread size?

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    Quote Originally Posted by borne2fly View Post
    That's true, I'm free to make better ones. Ideally I'd like to make them all Allen heads but I don't have a rotary broach, at least not yet. Dear Santa ......
    Buy long (short thread long shank) Allen headed bolts, cut off threaded section & rethread to spec.

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    Quote Originally Posted by Loner Industries View Post
    How hard are the tool holders? Do you have room to drill them out and tap them to a source able thread size?
    They're mild steel. I could re-tap the lot of them, but I'm only missing a few of the bolts so it's actually easier to make the bolts.

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    Quote Originally Posted by Limy Sami View Post
    Buy long (short thread long shank) Allen headed bolts, cut off threaded section & rethread to spec.
    Hadn't thought of that. I like it. I do have a few stainless Allens floating around, and as I recall I had to modify the heads for something else and they were relatively easy to machine.

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    I had to make a few 1/4-24 nuts a while back for a 1920s Indian Motocycle (not a typo) transmission and was able to buy a tap from Missouri Tool in Fenton, MO. Indian also liked 12-28 screws. These were common sizes at one time but fell out of use. It wouldn't be worthwhile for the few you need, but sometimes a Geometric chaser can be opened or closed to the next size, like going from 8-32 to 10-32. I didn't try going from 10-24 to 1/4-24 because I needed nuts for existing studs, not bolts. AFAIK the thread shape is standard Americano or so close to it that it doesn't matter.

    Bill


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