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Thread: What caused this

  1. #1
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    What caused this

    Had a friend bring to me a work piece that he had just threaded 7/8X14 using a Valenite lay down threading insert/ material was bought as 7/8Dia. O-1 annealed . I took it to another friend and had him that a picture with his microscope here is what the threads look like under high magnification. What caused the threads to look like this???

    Chet

    Click image for larger version. 

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    Last edited by coyotechet; 06-14-2020 at 10:08 AM.

  2. #2
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    No idea, but those threads will sure hold oil!

    Interested to hear what caused that. Maybe the insert wasn't tight in the holder, or there was a chip between insert and holder?

    Justin

  3. #3
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    Too much chatter for a loose or chipped cutter. looks like the workpiece is of very low machinability.

    What is the workpiece material supposed to be?

    .

  4. #4
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    O-1 in the annealed state has a low machinability. It requires a high surface feet per minute with a high quality cutting fluid to acquire any type of finish.

    Without seeing the setup, itís difficult to ascertain the exact problem. I do this on a regular basis in my shop when one of my men are having difficulty. Can you give a description of his setup?

  5. #5
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    Too much material hanging out of the chuck? No tailstock center?

  6. #6
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    last time i seen that is worn gears on a lathe

  7. #7
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    I personally think that Jackie is right on to slow of a speed (cut). I really have know idea both my friend and I thought 0-1 annealed would be the right material to use.
    Here is what I know he has a really nice (like new) Clausing 12" lathe and was using a New carbide laydown insert he say's that it's a Valenite uncoated
    was using [B]back gear at low speed 50/75[/B] and slow feed and light cuts because it was cutting (Sh###) from the first cut. I have never seen any thing like it before as he and I know that he has been cutting threads for a Long time like me he is not a machinist, but has been playing with lathes for well over 40 years.

    P.S. Nice tight Lathe and Gears /the piece was being held with 8" 4jaw chuck and only sticking out little little over 2 inches.
    I have not seen the 4 jaw chuck but he says it is old but good shape with very little ware if any.
    He is out of town and won't be back for until mid week so until then I won't be able to ask more.


    Chet
    Last edited by coyotechet; 06-16-2020 at 10:43 AM.

  8. #8
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    I agree with what Jackie said but seeing the setup would help. Also, there are different inserts that are much more tolerant of low speeds, feeds and pressure.

    What's the od of the part/thread?
    It looks more like too slow with his given threading tool than it does chatter from poor setup, to me. I'd try it at about 350 rpm, if possible.

  9. #9
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    Interesting? Jackie would he have been better off to use a HSS tool bit at that slower speed with that material.

  10. #10
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    very low speed with carbide
    e insert will give you the same results
    i cut minefrom the chuck with reverse cutter at +500 rpm

  11. #11
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    Quote Originally Posted by coyotechet View Post
    Had a friend bring to me a work piece that he had just threaded using a Valenite lay down threading insert/ material was bought as O-1 Annealed. I took it to another friend and had him that a picture with his microscope here is what the threads look like under high magnification. What caused the threads to look like this???

    Chet

    Click image for larger version. 

Name:	14 tpi.jpg 
Views:	450 
Size:	181.6 KB 
ID:	23662
    Looks like tool chatter.
    As in holder not tight enough.

  12. #12
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    Yes 50 /85 is to slow using A good carbide insert (Valenite C6 grade laydown) 50/85 not sure of the slowest speed on the Clausing.


    350/500 is to fast of a speed to kickout safely with out crashing for him (@74 plus and for me also @82today) that is why the slow speed.

    He is going to try and recut/thread the same piece of O-1 annealed 7/8X14 using HSS (Crucible REX76) that I just gave him) in week or so.

    Chet

    PS I just read the above post. That is what I first said looks like chatter. Know way using a good heavy duty 8" 4 jaw with the part sticking out only 2 Ĺ max. every thing tight as H#!!.
    Last edited by coyotechet; 06-15-2020 at 10:26 AM.

  13. #13
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    i saw this

    Quote Originally Posted by mwezell View Post
    I agree with what Jackie said but seeing the setup would help. Also, there are different inserts that are much more tolerant of low speeds, feeds and pressure.

    What's the od of the part/thread?
    It looks more like too slow with his given threading tool than it does chatter from poor setup, to me. I'd try it at about 350 rpm, if possible.
    when tool chiped

  14. #14
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    Somewhere's on the innertube there's videos showing how a carbide tool removes metal VS how a HSS bit shears it like a knife.

    When I see that look, which I call "pulling" it's a sure sign need to ramp the speed up.....'WAYYYYY up. Or dig in deeper and crank up the coolant. Or both.

    Which I generally cannot do.

    Two of my sons are engineers and when I talk about "feeds and speeds and what I'm fighting on my lathe" .......... they look at me as if I'm from another planet

    I talk in "ten's" and "hundreds" of rpm's and surface speed, they talk in thousands.... And the stuff they machine, and the way they machine it is literally beyond the capabilities of my manual equipment. I'm personally just now getting back in touch with the equipment enough to know when to say "ooops! this ain't working!" and radically change something, like try a different material

    Lathe I'm pretty good, Bridgeport is still day by day.

    I will say this, In My Opinion that surface finish is a sure sign of "call it a day, this IS NOT a settings issue but instead a bad mix of materials"

    For ME

    In other words that's what I would do.

    Because I don't know no better

  15. #15
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    Use the HSS cutter at those speeds. You can get HSS inserts from A.R.Warner if you don't want to grind them.

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