O1, A2 or W1 to make a tap?
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    Default O1, A2 or W1 to make a tap?

    I need to make a tap for a size not commercially available. (It is around 5/8"-14). McMaster lists O1, A2 and W1. W1 is the only one that has taps under the applications. Would that be best for me? I've never made a tap and haven't done heat treating. I will have an oven soon. It has a microprocessor control that can ramp down to properly air cool. If I oil quench I don't know what kind of oil to use. I haven't looked in the Machinists Handbook for that yet because I was hoping to use air or water. Thank you for your help.

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    Taps are made of W, O, and A tools steels, and HSSs. And a lot more for specialized uses.

    You haven't specified the problems sufficiently.

    Is this a one-off that you are making for yourself? Or a product you intend to sell?
    --> One-off suggests not worrying about material costs as much as machiniabiity and heat-treat stability, and toughness (get A2)
    Will this be used in a hand-tapping operation or using a tapping machine or a drill press with a tapping head?
    --> Machine operation - consider HSS
    How many times will this tap be used (and what duty severity will it see) in its lifetime? Chasing two holes in cast iron in a vintage machine tool , or threading as many new holes as possible in 304 or Ti? Will you be tapping hardened steels?
    --> Here, others are more expert that I. But horses for courses.

    One thing to be aware of is that a tap is not just a hardened bolt with grooves. For any type of duty cycle at all, the threads must be relieved.
    Assuming you get the tap forms relieved properly, can you get away with "as machined" and hand finished taps? If not, how do you propose to grind the thread forms? Here's a thread on tap grinding:
    Tap grinding

    Unless you really are Jonesin' to spend a half a year learning to cut, heat-treat, temper, and grind taps (and want to make or buy the equipment needed to relieve and grind the tap) it may be worth having the tap made. Don't want to crush anyone's dream, but I'm just saying don't expect to goof around in the shop for couple weeks and come up with a commercial-grade tap.

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    What is the actual size needed,Home Depot has a 5/8 14.

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    Unless it's ABSOLUTELY not available from places like here TAPS at VictorNet IME making your own ''old school'' cut thread taps is time consuming, often frustrating and meets with varying degrees of success.

    You also don't state what material it's to be used on.

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    Only one I was ever asked to make - back in the sixties - was for taking a CORD automobile exhaust manifold out to some over size where it connected to the header pipe with a gland nut affair - over 3 1/2" -12 if I recall correctly

    Made it from 01. Was not relieved like all real taps, so was a bear to turn - in cast iron

    Customer was happy

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    Depends on how much use and how good it has to be. I needed an M5-0.5 last night with no time to buy one. Took me maybe 20 minutes to make, including the time to change the change gears on the lathe. Used a piece of 1/4" O1 from the scrap bucket, but quenched it in water. Ground 4 flats at a taper on the end. Worked just fine in brass and would have worked fine in mild steel. It helps that I have a nice propane-oxygen bench torch nearby. Here's a thread from long ago- Making taps

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    FWIW, I am endorsing Conradís linked tap making method. For just a few holes such a tap works fine in most materials. Iíve used O1 heated with a MAPP gas torch and quenched in canola oil. Very simple and very quick as he says.

    If you want to see if performance can be enhanced, there is nothing that says you canít also use a die grinder/Dremel/fForedom to more closely approximate commercial taps. But, I usually just grind 3 or 4 flats as shown and get on with it. I much prefer my Guhring taps when cutting common threads. But, for an odd one or a few holes, itís often easier to just make the tap in far less time than it takes to hunt one down and make the order let alone wait for delivery.

    BTW, you donít need to spend hours with perfect heat treat schedules. Heat it to bright cherry, quench, and then temper. The entire process of hardening and quenching should take less than 5 mins.

    Denis

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    Quote Originally Posted by mc3608 View Post
    What is the actual size needed,Home Depot has a 5/8 14.
    Amazing. The bolt is .655" so I don't know if a .625" tap would help. This is to repair a Posi Lock brand puller. Posi Lock told me the thread was "proprietary" so I think I have to make a tap. It will be to repair 1 thread 1 time. I have chased the bolt threads on the lathe and I think they are usable, but it still gets tight when I try to use it. I think I can make the tap. I just need to expand my knowledge base. We do have a Hybco tap grinder at the office but no one knows how to use it.

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    To repair existing "almost ok" thread the tap doesn't need to be that special.
    Hard grade 8 bolt would make decent one-time use tool but since this is bastard size it won't work.
    I'd select the steel that you is feels easiest to harden on your equipment. Any of the mentioned ones will make tap enough good to repair one thread.

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    Quote Originally Posted by rickseeman View Post
    Amazing. The bolt is .655" so I don't know if a .625" tap would help. This is to repair a Posi Lock brand puller. Posi Lock told me the thread was "proprietary" so I think I have to make a tap. It will be to repair 1 thread 1 time. I have chased the bolt threads on the lathe and I think they are usable, but it still gets tight when I try to use it. I think I can make the tap. I just need to expand my knowledge base. We do have a Hybco tap grinder at the office but no one knows how to use it.
    Might be a 17mm x 1.75 pitch if you are shopping around. Puller screws are often a buttress thread form as well.

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    You could just spend the $13.55 and order one from Field Tool

    5814tap.jpg

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    If you're new to heat treatment definitely use plain old O1 steel. It's almost magically forgiving and surprisingly effective despite efforts to make it not work.

    As for making the actual tap aside from the advice here I'd suggest finding the oldest book you can at the library with "toolmaking" somewhere in the title and see what they suggest. It'll be simple and effective, along the lines of grinding your threaded blank tap on 3 sides making an equilateral triangle and tapering the end a bit and there you go. Technically almost plain wrong, practically unbeatable.

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    Quote Originally Posted by Conrad Hoffman View Post
    Depends on how much use and how good it has to be. I needed an M5-0.5 last night with no time to buy one. Took me maybe 20 minutes to make, including the time to change the change gears on the lathe. Used a piece of 1/4" O1 from the scrap bucket, but quenched it in water. Ground 4 flats at a taper on the end. Worked just fine in brass and would have worked fine in mild steel. It helps that I have a nice propane-oxygen bench torch nearby. Here's a thread from long ago- Making taps

    I can't personally imagine making a tap with just flats forming the cutting edge. you can cut gullets in seconds with an angle grinder and a cutoff wheel. (or a foredom flex shaft with a parting wheel if it is small). that way, you can choose whatever degree of rake you want. sure flats would work in brass, but, well, its brass.

    img_0939.jpg

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    Quote Originally Posted by rickseeman View Post
    ..... This is to repair a Posi Lock brand puller. Posi Lock told me the thread was "proprietary" ....
    Since this is a puller with a special thread size I wonder if it also has a special thread angle as normal threads are not real efficient.
    I'd look close at that thread since it's made to "work" in one direction only and a special.

    For a single use O1 should be fine and easy to HT.
    Making a tap is not an easy task and I wonder how much this puller is worth?
    Bob

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    Quote Originally Posted by cyanidekid View Post
    I can't personally imagine making a tap with just flats forming the cutting edge. you can cut gullets in seconds with an angle grinder and a cutoff wheel. (or a foredom flex shaft with a parting wheel if it is small). that way, you can choose whatever degree of rake you want. sure flats would work in brass, but, well, its brass.

    img_0939.jpg
    I've actually had better luck with the flats than gullets, but then I don't have an angle grinder. I was skeptical until I tried it, but the chips come out the front just fine. Works on steel too.

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    If you have a lathe on which you can propose to make a tap, why not single-point the internal threads you need?

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    Quote Originally Posted by rickseeman View Post
    Amazing. The bolt is .655" so I don't know if a .625" tap would help. This is to repair a Posi Lock brand puller. Posi Lock told me the thread was "proprietary" so I think I have to make a tap. It will be to repair 1 thread 1 time. I have chased the bolt threads on the lathe and I think they are usable, but it still gets tight when I try to use it. I think I can make the tap. I just need to expand my knowledge base. We do have a Hybco tap grinder at the office but no one knows how to use it.
    You state that you are chasing existing threads. Which means that the original threads are stripped. This, for a device whose entire purpose in life depends upon those threads. Do you see the path to disaster when it's said this way? If the device has already failed in service, chasing thrust threads is a losing battle. That thing is toast.

    A replacement part is available from Grainger for $150. Or, you could see if PosiLock gives you a good price. Or, from what I hear about Grainger, just about anywhere for a better price. Grainger lists the entire unit for $264.

    Is this the part you want to repair via chasing?



    The stated thread size for model 206 is "2/3-14". Which is is less than 2% different that 21/32-14. This is for the internal threads where the central rod of the puller is installed. If you really want to see if you can make the part work, why not just create a 21/32-14 threaded rod out of W-1 and harden and temper - then form chase the threads. But I think it's a fools errand.
    Last edited by bosleyjr; 10-28-2019 at 10:28 AM.

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    Quote Originally Posted by Conrad Hoffman View Post
    I've actually had better luck with the flats than gullets, but then I don't have an angle grinder. I was skeptical until I tried it, but the chips come out the front just fine. Works on steel too.
    Really? Who doesnít have an angle grinder?!?! Since exactly zero taps Iíve ever bought have a negative rake, Iím going with positive rake.
    What is your bad experience with gullets? Yea, weíve all busted taps, but mashing a tool in, instead of cutting with it, just doesnít seem right. As I said, you can customize the angle, so that seems better to me.

    I see no reason to go backwards in my options, since itís literally seconds to do it. Even with a bench grinder. (Edge of well dressed wheel).

    No flats for me!

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    Taps aren't that hard to make and make work well.
    Did this one about 10 years ago, it's 12mm x 40tpi - I needed a fine adjustment thread on a fixture collar I was making.
    Bit of O1, single point thread, flutes gashed with a ball nose endmill to give some rake, hardened with a propane torch.
    Cut just fine in some P20 steel.

    tap.jpg

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    Nice tap! I could have single pointed the parts I needed, but it would have taken me longer to grind a tool for that, than to make the tap. I don't have any small ID threading tools. Should, but don't.


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