Form tapping M12 in 4140PH? - Page 2
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  1. #21
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    Quote Originally Posted by Pete Deal View Post
    Bought the tap, first part, tap broke.
    For my 303SS I drilled and reamed to the precise diameter called for by the form tap. It's not the same as for a cut tap, since it's displacing material. Worked the first time, and several hundred parts.

  2. #22
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    Quote Originally Posted by mhajicek View Post
    For my 303SS I drilled and reamed to the precise diameter called for by the form tap. It's not the same as for a cut tap, since it's displacing material. Worked the first time, and several hundred parts.
    I understand that. I form tap all the time. Just not 303 or for that matter 4140ph. My point is for a high value part one of- play it safe.

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    Quote Originally Posted by Finegrain View Post
    16,000 RPM spindle is only good for 27 Nm instantaneous (my 2016 S700X1 anyway), so maybe it makes it, maybe it doesn't.

    Regards.

    Mike
    Oh, real specs are good. The specs on the 16k weren't clear with what I found online. In the brochure, the 16k can't tap as big as the 10k. Well, this is why I calculate.

  5. #24
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    Quote Originally Posted by Pete Deal View Post
    You didn't say how many holes or how many parts. I assume just one plate?

    If just one plate I would absolutely not form tap it. I had a job recently, 300 little 303 stainless bullet nose things (lathe work) with a 10-32 hole. I read a bunch of these posts and figured sure form tapping works fine on 303. Bought the tap, first part, tap broke. Switched do a spiral point tap and did the whole bunch no problems. Probably if this was a job that was worth a the process development time and money it would be worth it but for one part I would go with thread milling. Or if just a few holes I think I would just tap them with a cut tap in a little and finish them by hand. But I think a single cutter thread mill ought to work.
    Just one plate, six holes.

    In aluminum I would for sure run a form tap -- it's the thick 4140PH that made me doubt myself. I form tap almost everything, it's really rare for me to get out a cut tap or thread mill. But most of what I do is M8 or smaller and those are easily done.

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    One part, six holes, threadmill all the way. Safest bet.

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    Quote Originally Posted by trochoidalpath View Post
    Thanks for your feedback everyone.

    I’ll try to find a thread mill with enough reach — that might be tricky. If I can’t find a reasonable one, I’ll probably try it with a spiral point cut tap.
    That's what I would do.
    #1 option = thread mill.
    #2 option = spiral point tap, cut shallow. Finish by hand with oil or whatever.

    1 offs can be painful enough - when they already have a lot of work into them, de-risk!

  9. #27
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    OK, I figured I owed this thread an update.

    I form tapped some M8-1.25 holes on the back side of the part with absolutely no problem. Spindle load was solidly in the green and the threads looked fantastic. Tried it on some M10-1.5s, tap slipped and spun in the collet and stalled out — no damage, so it’ll be easy to recover. (The Speedio tap recovery feature is fantastic!)

    I was using ER25 holders with high quality collets. I’ll have to try again in some scrap with tap collets and see if that works a bit better. Meanwhile, off to threadmill….

  10. #28
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    Quote Originally Posted by trochoidalpath View Post
    OK, I figured I owed this thread an update.

    I form tapped some M8-1.25 holes on the back side of the part with absolutely no problem. Spindle load was solidly in the green and the threads looked fantastic. Tried it on some M10-1.5s, tap slipped and spun in the collet and stalled out — no damage, so it’ll be easy to recover. (The Speedio tap recovery feature is fantastic!)

    I was using ER25 holders with high quality collets. I’ll have to try again in some scrap with tap collets and see if that works a bit better. Meanwhile, off to threadmill….
    Are you using nominal size collets on that tap shank?

    You really shouldn't need a tap collet for that, but you will need one that fits the shank exactly. If you are using inch collets for example and the tap shank is metric, no good. All DIN and ISO taps have shanks sized in whole mm, so nominal collets sizes with no collapse, idk if that's true of whatever taps you have over the pond.

    I have done up to M14 form tapping in 17-4 H900 in an ER25 without slipping.

  11. #29
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    Quote Originally Posted by trochoidalpath View Post
    tap slipped and spun in the collet
    Get a tap collet, it will never spin on you agian.
    Do you have the 10k or 16k spindle?

  12. #30
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    Quote Originally Posted by gregormarwick View Post
    Are you using nominal size collets on that tap shank?

    You really shouldn't need a tap collet for that, but you will need one that fits the shank exactly. If you are using inch collets for example and the tap shank is metric, no good. All DIN and ISO taps have shanks sized in whole mm, so nominal collets sizes with no collapse, idk if that's true of whatever taps you have over the pond.

    I have done up to M14 form tapping in 17-4 H900 in an ER25 without slipping.

    How it was explained to me 30 yrs ago:

    In the USA we have what is known as "soft metrics" when it comes to taps.
    Our metric taps still have "inch equivalent" shanks.
    Which as you likely know - are not on a standard size anyhow.

    I have to wonder at what point in time they will forego that practice?
    I would think that some here would be metric equiv shanks, but I have not come accrost any yet I don't think?


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    Quote Originally Posted by Houndogforever View Post
    You may live to regret it, but I sure as hell want to see it happen.
    Personally, I have never form tapped anything except aluminum.
    Bro I TOO want to see this fail.

    I form tap aluminum all day, but never 4140. That sounds like a good idea to break a tap.

    From my limited knowledge form tapping should be used on ductile materials. Technically 4140 has ductility butttttt yea I wouldn't want to test that theory. Stainless steels can be form tapped. Copper. Brass.

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    Quote Originally Posted by Wsurfer View Post
    Would peck tapping not be a viable option ?. I only ask because I haven't tried it yet on my 10k S500. 1/2-13 in 1018 through 1/2" plate is as much as I've needed so far.
    Yes...although with form tapping I have never done peck tapping. Cut tapping yes, peck tapping works a treat in steels if your machine can do peck tappng

  16. #33
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    Quote Originally Posted by metalmadness View Post
    Bro I TOO want to see this fail.

    I form tap aluminum all day, but never 4140. That sounds like a good idea to break a tap.

    From my limited knowledge form tapping should be used on ductile materials. Technically 4140 has ductility butttttt yea I wouldn't want to test that theory. Stainless steels can be form tapped. Copper. Brass.
    It works fine, I do it all the time.

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    Quote Originally Posted by metalmadness View Post
    Bro I TOO want to see this fail.

    I form tap aluminum all day, but never 4140. That sounds like a good idea to break a tap.

    From my limited knowledge form tapping should be used on ductile materials. Technically 4140 has ductility butttttt yea I wouldn't want to test that theory. Stainless steels can be form tapped. Copper. Brass.
    4140 is sure more ductile than 360 brass!



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    Quote Originally Posted by gregormarwick View Post
    Are you using nominal size collets on that tap shank?

    You really shouldn't need a tap collet for that, but you will need one that fits the shank exactly. If you are using inch collets for example and the tap shank is metric, no good. All DIN and ISO taps have shanks sized in whole mm, so nominal collets sizes with no collapse, idk if that's true of whatever taps you have over the pond.

    I have done up to M14 form tapping in 17-4 H900 in an ER25 without slipping.
    I am probably in the minority here but I use tap collets for literally everything, last week I did some 0-80 form taps and used the tap collet. For me it is just easier than trying to find the right ER collet, with tap collets there is only one correct size. And I never have to worry about slipping.

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    Quote Originally Posted by metalmadness View Post
    I am probably in the minority here but I use tap collets for literally everything, last week I did some 0-80 form taps and used the tap collet. For me it is just easier than trying to find the right ER collet, with tap collets there is only one correct size. And I never have to worry about slipping.
    I honestly don't own a single tap collet.

    Actually that's not quite true, I have a couple of ER32 built in tension-compression collets, but 99.9% of the taps here just go in plain collets and it's not an issue.

    The difference in grip between nominal collet/shank and collapsed collet/undersize shank is massive.

  21. #37
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    Quote Originally Posted by gregormarwick View Post
    Are you using nominal size collets on that tap shank?

    You really shouldn't need a tap collet for that, but you will need one that fits the shank exactly. If you are using inch collets for example and the tap shank is metric, no good. All DIN and ISO taps have shanks sized in whole mm, so nominal collets sizes with no collapse, idk if that's true of whatever taps you have over the pond.

    I have done up to M14 form tapping in 17-4 H900 in an ER25 without slipping.
    It's an OSG form tap with a 9.67 mm shank -- the exact tool is 1635010156. I used an Lyndex-Nikken 10mm-9.5mm collet.

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    Quote Originally Posted by Mtndew View Post
    Get a tap collet, it will never spin on you agian.
    Do you have the 10k or 16k spindle?
    I have a 16K spindle.

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    OK, everyone's overnight comments made me feel like I was being too much of a chicken.

    I ran the same collet and tap through the ultrasonic cleaner to get them squeaky clean, reassembled and torqued them to ~90 ft-lbs. I dropped a 6mm end mill into the bore just to make sure that they were exactly on size. Tap cycle went flawlessly though the spindle meter was flickering into purple -- I do not think I would care to run a M12 form tap in 4140PH on a 16K Speedio.

    Thread quality looks great to me. I'll call this a success, thanks everyone!

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  25. #40
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    Quote Originally Posted by trochoidalpath View Post
    OK, everyone's overnight comments made me feel like I was being too much of a chicken.

    I ran the same collet and tap through the ultrasonic cleaner to get them squeaky clean, reassembled and torqued them to ~90 ft-lbs. I dropped a 6mm end mill into the bore just to make sure that they were exactly on size. Tap cycle went flawlessly though the spindle meter was flickering into purple -- I do not think I would care to run a M12 form tap in 4140PH on a 16K Speedio.

    Thread quality looks great to me. I'll call this a success, thanks everyone!
    I have never seen purple on the spindle load. Does that come after red?


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