Why 62.5 degree inserts instead of 60 degrees
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    Default Why 62.5 degree inserts instead of 60 degrees

    Why do 62.5 degree rhombic inserts exist? I can understand the 60 degree ones for threading but I am not aware of any use for 62.5 degrees. Is there some common flare or groove feature that is 62.5 degrees?
    The angles are so close I do not under stand the need for both. The 62.5 degrees is close enough to rough cut a thread and finish with a tap or die I suppose.
    Bill D

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    Quote Originally Posted by Bill D View Post
    Why do 62.5 degree rhombic inserts exist? I can understand the 60 degree ones for threading but I am not aware of any use for 62.5 degrees. Is there some common flare or groove feature that is 62.5 degrees?
    The angles are so close I do not under stand the need for both. The 62.5 degrees is close enough to rough cut a thread and finish with a tap or die I suppose.
    Bill D

    "Threading" Eh?

    Field First Sergeant "Willie" Williams, 101'st into a bridge too far, then Bastogne:

    "If necessity is the Mother of invention, then ASSUMPTION is the Mother of all f**kups."

    But let's open the mind to learning and research of "possibilities", shall we?

    The cut is "generally" made into a cylindrical object. Surface is curved, in other words. Tooling is not often dead-flat to a dead-level radial line, has some rake angle or another, rather.

    What is the angle it actually GENERATES in the stock when in use, straight-in plunge, no compound rest monkeying about, and set where the maker expected it to be?

    Not ALL threads are 60-degree, not even CLOSE-to, BTW. There are "standards" for over a hundred of them, after all.

    And what d'you know about "class" of thread fits, and why each has a useful place at the table that is intentional, not just the accidental byproduct of lousy QA?

    The use that you - or I - are "not aware of" may be some other whole industry's ordinary Day Job rice-bowl?

    Threading ain't the only determinant of an effective angle for a given cutting-tool and the material it is made of.

    Sometimes it has to do with how Alloys react to tool approach angles for best rate of removal, best longevity per-edge, ordinary straight turning.

    Read as: "more money in the bank, less wasted in the recycle bins of stock, Carbides, power bill, machine-wear, and hours of labour, summed."

    D'you suppsoe the angle presented with only ONE of the edges active at a go might depend as much on how the insert's POCKET is aligned as on the insert shape alone?
    The OTHER edges generally wait their turn, yah?

    The insert-makers might have that sort of klew? Not all that often they ship the buggers in packs of only the one ever made, yah?

    Saved the best for last. Of course.

    See "boring bars". DCMT or DCGX insert. Lowly Shars catalogue.. or

    "Right here, on PM", even:

    Best Boring Bar and Insert Style for 6061T6

    Common as dirt "shiny wood". Go figure.


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    Quote Originally Posted by thermite View Post
    "Threading" Eh?

    Field First Sergeant "Willie" Williams, 101'st into a bridge too far, then Bastogne:

    "If necessity is the Mother of invention, then ASSUMPTION is the Mother of all f**kups."

    But let's open the mind to learning and research of "possibilities", shall we?

    The cut is "generally" made into a cylindrical object. Surface is curved, in other words. Tooling is not often dead-flat to a dead-level radial line, has some rake angle or another, rather.

    What is the angle it actually GENERATES in the stock when in use, straight-in plunge, no compound rest monkeying about, and set where the maker expected it to be?

    Not ALL threads are 60-degree, not even CLOSE-to, BTW. There are "standards" for over a hundred of them, after all.

    And what d'you know about "class" of thread fits, and why each has a useful place at the table that is intentional, not just the accidental byproduct of lousy QA?

    The use that you - or I - are "not aware of" may be some other whole industry's ordinary Day Job rice-bowl?

    Threading ain't the only determinant of an effective angle for a given cutting-tool and the material it is made of.

    Sometimes it has to do with how Alloys react to tool approach angles for best rate of removal, best longevity per-edge, ordinary straight turning.

    Read as: "more money in the bank, less wasted in the recycle bins of stock, Carbides, power bill, machine-wear, and hours of labour, summed."

    D'you suppsoe the angle presented with only ONE of the edges active at a go might depend as much on how the insert's POCKET is aligned as on the insert shape alone?
    The OTHER edges generally wait their turn, yah?

    The insert-makers might have that sort of klew? Not all that often they ship the buggers in packs of only the one ever made, yah?

    Saved the best for last. Of course.

    See "boring bars". DCMT or DCGX insert. Lowly Shars catalogue.. or

    "Right here, on PM", even:

    Best Boring Bar and Insert Style for 6061T6

    Common as dirt "shiny wood". Go figure.

    Bill,
    That was wonderful bullshit, but you didn't answer the OP's question. Why? Examples?

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    Quote Originally Posted by Bill D View Post
    Why do 62.5 degree rhombic inserts exist? I can understand the 60 degree ones for threading but I am not aware of any use for 62.5 degrees. Is there some common flare or groove feature that is 62.5 degrees?
    The angles are so close I do not under stand the need for both. The 62.5 degrees is close enough to rough cut a thread and finish with a tap or die I suppose.
    Bill D
    maybe some company made them as an advertisement gimmick and the others just followed suit?

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    Quote Originally Posted by Bill D View Post
    Why do 62.5 degree rhombic inserts exist? I can understand the 60 degree ones for threading but I am not aware of any use for 62.5 degrees. Is there some common flare or groove feature that is 62.5 degrees?
    The angles are so close I do not under stand the need for both. The 62.5 degrees is close enough to rough cut a thread and finish with a tap or die I suppose.
    Bill D
    I haven't seen 62.5 degree rhombic inserts and Google doesn't give much results either.

    Are you mixing insert angles and toolholder angles? 62.5 degree approach angle is "symmetric" or "neutral" for 55 degree insert. (90-55/2 = 62.5 degrees)

    https://www.imc-companies.com/taegut...llust/1142.gif

    Before you ask why 55 degree rhombic insert is so common? Dunno, but it matches british Whitworth thread angle.

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    The manufacturer will probably tell you it is stronger than 60° or some other such claim.

    I suspect the real reason is so that you can not use them for threading. So you have to BUY threading inserts.

    Follow the money trail.

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    I have never seen or made a 62.5 degree insert.
    MattiJ may be onto something that makes sense and kudos to him as I did not even think of that answer.
    The 55 degree diamond is a very old standard and is not a threading insert. Its for profiling and getting into places a S,D, or T can not.
    Bob

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    Quote Originally Posted by EPAIII View Post
    The manufacturer will probably tell you it is stronger than 60° or some other such claim.

    I suspect the real reason is so that you can not use them for threading. So you have to BUY threading inserts.

    Follow the money trail.
    In fairness, most "turning" inserts have various tip radii options, and unless you're cutting UNJ-style threads you really should be using proper threading inserts anyway, which have a more strict control of the tip geometry.

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    Quote Originally Posted by steve-l View Post
    Bill,
    That was wonderful bullshit, but you didn't answer the OP's question. Why? Examples?
    Of course not. That was punishment for sloth. So he'd do his own homework, next go and in years to come to avoid my cantankerous arse putting scar-tissue on his weary eyeballs!

    Any of us expect to live forever? Beginning to think that Army recruiting Sergeant LIED!



    All he had to go was go ogle!

    The eventual link leads back to a discussion. "Right here on PM".

    Works a treat on 6061T6. Anything works good, folks will take any angle as.. works good. Within limits, the pocket orientation matters, too, so the insert isn't sole player.

    Oh. Said that arredy, yah?

    Simple enuf for earning a crust.

    Politics of it all b'long over in the Drivel in Europe Troll'em.... 'er "Forum"

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    Quote Originally Posted by Bill D View Post
    Why do 62.5 degree rhombic inserts exist? I can understand the 60 degree ones for threading but I am not aware of any use for 62.5 degrees. Is there some common flare or groove feature that is 62.5 degrees?
    The angles are so close I do not under stand the need for both. The 62.5 degrees is close enough to rough cut a thread and finish with a tap or die I suppose.
    Bill D
    Please cite example.

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    I guess I was wrong. It is for 55 degree inserts but they claim a 62.5 degree angle. So they mean the pocket side angle relative to the bar axis not the insert angle. I do not understand why they do not say 90 degrees.
    I guess all those cheap inserts are 55 degree not 60's. No wonder I had to finish up with a die to get good threads.
    Insert nomenclature is confusing for me.
    Bill D

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    You will get no arguments from me on that one. In fact, the range of thread sizes that can be made with a single insert (single tip radius) is rather limited. Ideally a 6-40 thread would have a different tip radius than a 6-32.

    But anyone up for a survey question as to just how many of us have a range of inserts for the various threads that we cut? I bet the results, if honest, would be rather disappointing. I guess a NASA shop may have all sizes and probably a few other large companies, but what about you guys working in a one or two man shop? Come on, be honest. Just how many different threading inserts do you actually have? Or would you order one specifically for a thread if you did not have the correct one.

    I do have several, but they are shop ground HSS tool bits, not carbide inserts. And I do either grind new ones or touch-up existing ones as needed.



    Quote Originally Posted by Milland View Post
    In fairness, most "turning" inserts have various tip radii options, and unless you're cutting UNJ-style threads you really should be using proper threading inserts anyway, which have a more strict control of the tip geometry.

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    Quote Originally Posted by Bill D View Post
    No wonder I had to finish up with a die to get good threads.
    Insert nomenclature is confusing for me.
    Bill D
    Anything I have - or can easily GET a die for - I start AND finish with it, actually! Taps even more so.

    They tend to turn out right on spec. Every time.

    Why mess?


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    Round here, the ******mechanics use taps and dies to clear threads on parts back form the plating shop...
    Only guaranteed sharp threading tool in the shop is the lathe coupled with my well guarded inserts....

    Cheers Ross

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    Quote Originally Posted by AlfaGTA View Post
    Round here, the ******mechanics use taps and dies to clear threads on parts back form the plating shop...
    Only guaranteed sharp threading tool in the shop is the lathe coupled with my well guarded inserts....

    Cheers Ross
    LOL! I just buy better taps & dies, grind meself the odd Rex 95 for "the bigger stuff"!

    Don't gots no steenkin' "inserts" since my wore-out putz decided to retire.. and go into a coma...

    So .. whatever ELSE?

    Some among we FORMERLY ******g - (and proud-of-it!), mechanics are no longer ******g!



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