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Thread: Parting tool

  1. #31
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    Quote Originally Posted by jack620 View Post
    The top surface is the wrong shape. You need to grind it flat.
    That's the profile of the stock - I'm going to guess it's to provide some kind of chip-breaking feature. If you look at the last pic, the top is ground flat at the cutting edge.

  2. #32
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    I always grind mine at a slight angle so it cuts tbe part off first, then leaves the nib on the stock which is removed after the part is gone.
    Using Tapatalk

  3. #33
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    Quote Originally Posted by RustyArc View Post
    If you look at the last pic, the top is ground flat at the cutting edge.
    So it is. When I tried to look at the photo on my iPad earlier I couldn't get it to load.
    Chris

  4. #34
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    If this helps anyone,

    I went looking for more info on chip breaking for a HSS parting Tool and found this:

    https://www.youtube.com/watch?v=phhhbB2rmrA

    Its similar to what I already have on a 3/4" x 1/8" though my ground groove is not as deep or as wide as the one shown. THE HSS is mounted in an old Lock type tool holder to which
    I have welded a piece of 16mm SQ. cold rolled steel which, in turn fits in the QCTP.

    I dressed my HSS tool after grinding with a diamond lap stone. My groove was formed with a dremel cut off wheel to make a central line.The semi circular groove was formed with a dremel mounted parallel diamond burr. The chip does not break often as I would like but comes out a lesser width than the tool.

    My original source of info about the chip breaker groove was in an old machinists book I had a lend of.

    My tool parts up to 30mm stainless OK,but I do have to minimise overhangs and use a brush on, sulphurised oil as well as observing the other normal requirements.

    <edit : Sorry,no pics available due to a lack of a working camera/camera phone in our household>

    Grahame

  5. #35
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    Quote Originally Posted by jack620 View Post
    The top surface is the wrong shape. You need to grind it flat.


    Sent from my iPad using Tapatalk
    Yes the tip is ground flat on the top.
    or do you mean it should be flat further back as well ? Come to think of it, that makes sense.

  6. #36
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    Quote Originally Posted by Grahame Collins View Post
    Its similar to what I already have on a 3/4" x 1/8" though my ground groove is not as deep or as wide as the one shown.
    My carbide insert parting tool has a very similar scooped-out centre profile to that shown at the end of that video. I'm not entirely sure whether it's actually causing chips to break though.

  7. #37
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    The hollow top of the parting tool is to cause the chip to fold in slightly and become narrower so that they do not catch in the slot and thus assist with chip clearance.

    Ken

  8. #38
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    Quote Originally Posted by Dave J View Post
    That looks great, but he does have a rigid machine.
    Always wondered why the factory supplied carbide parting tips don't come sharpened with the right side higher, so the part comes off first nice and flat and the nib is left on the stock and removed after the part has left.
    I always sharpen my HSS this way.
    You can buy inserts angled as you suggest but they wander to the right on a deep part off.

  9. #39
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    Quote Originally Posted by Dave J View Post
    I always grind mine at a slight angle so it cuts tbe part off first, then leaves the nib on the stock which is removed after the part is gone.
    My other parting tools are ground that way.
    I originally ground this blade that way too but because the blade is thin I found it flexed and pulled the blade sideways.

  10. #40
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    The HSS blade is working for me. I am using the same profile for steel, brass, aluminium and stainless/s. I am parting off stainless steel in the video below, I think I could run it a bit slower, maybe a bit too fast on this one?

    Sorry about the noise from the video...
    Attached Images Attached Images

  11. #41
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    Quote Originally Posted by jackaroo View Post
    The HSS blade is working for me. I am using the same profile for steel, brass, aluminium and stainless/s. I am parting off stainless steel in the video below, I think I could run it a bit slower, maybe a bit too fast on this one?

    Sorry about the noise from the video...
    Ripping through it, great work
    Using Tapatalk

  12. #42
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    Quote Originally Posted by Dave J View Post
    I agree with this type of parting blade and had great results.
    I've never tried rear mount running in reverse, but will get around to it one day when I decide to drill my lathe cross slide
    Quality HSS (as you have) helps a lot over most of the Chinese rubbish sold as HSS parting blades.

    What Dave, P&W, never heard of em, what would they know about metallurgy?

  13. #43
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    Hi jackeroo,
    Once you get those little curly C's you know its going alright.

    I like plenty of lube and use a big bore syringe filled with Tricky's heavy duty tapping and cutting lube. It stinks a bit but rarely much smoke.

    I buy it cos its made here in Queensland, Bundaberg to be precise.

    Its like Pecks paste, a little bit goes a long way.

    Grahame

  14. #44
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    The one in that clip is 30mm is diameter. For bigger stock to do step parting, that is to cut about 10mm in then widen it by 1/2 of the blade width, continue to go pass the cut by 5-10mm then move the blade back to the first position, keep doing that until it is done. I have done 50-60mm before. Longer part sticking out from the chuck I will use tailstock to support the end. If there is no hole in the middle I find that the blade can ditch under when it goes to near the end.

    Regards,
    Trong

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