• Re: Those Cheap Diamond Inserts

    From Peter Fairbrother@21:1/5 to All on Tue Aug 20 18:17:05 2024
    On 20/08/2024 07:50, Charlie+ wrote:

    [...]
    Only hobby level now.. https://www.ebay.co.uk/itm/115334715488?_nkw=diamond+inserts+carbide+lathe&itmmeta=01J5Q723XNA0GREWTN8RFZEQK2&hash=item1ada7c1860:g:YyUAAOSwUtJiUKWN&itmprp=enc%3AAQAJAAAA4HoV3kP08IDx%2BKZ9MfhVJKnC8gu8jBQODZUzjY6nfSpuZas%
    2FJzGcWIYLgG5EPfxVgG0wH1c4QdrYrUHqD4z98NSE8atbz28SHAAsTTB%2FvXsdw1KSXcN7%2Bx6cwyg%2FcKXwvDq3eEqXZbpx%2Bzxtc0f0%2Fp0BsyoIUtnlZlJQI86p6TyhETkaZsGuuwYw1Ayo2CHAORe6WE1WiaDElO8xogeQY1mItmsxVxjRLhavW15vEW5hMGkyR8srWzmxrGq4dX%2B9yZ23zhsDDiiDdifsQ%2Bk8r7IRPefZ9T%
    2FppdLbpKF%2FwpjM%7Ctkp%3ABk9SR_S-iOetZA

    Those are PCD polycrystalline diamond tipped inserts. Diamond crystals
    in a cobalt alloy matrix. For very hard materials sometimes, but far
    more often for extreme wear resistance.

    It says for non ferrous [..]
    The carbon in the diamond dissolves in iron and steel (and nickel
    alloys), so they don't last long on steel. You can use CBN cubic boron
    nitride on steel etc for longer life, about the same price.

    Hobby level chaps (and most small-batch pros, indeed most pros) should generally stick to HSS or carbide, unless they are doing something unusual.

    Can they be touched up if/when the edge goes?

    No. Carbide inserts can sometimes be touched up with diamond (though
    it's usually not worth doing unless you want something special), but not
    PCD or CBN.

    I know its only a single but looks uncheap to me! C+

    Last time I bought any they were £20-odd each, and that was years ago.


    Peter Fairbrother

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  • From Bob La Londe@21:1/5 to Jim Wilkins on Tue Aug 20 11:29:28 2024
    On 8/19/2024 4:44 PM, Jim Wilkins wrote:
    "Bob La Londe"  wrote in message news:va0hrc$321n0$1@dont-email.me...

    I have freehand ground a lot of things, and I can probably make an
    adequate threading cutter, but a simple miter gage and slot in a tool
    rest makes it achievable for nearly anybody.  Even a puttering geezer.
    Bob La Londe
    --------------------------------------
    So does a Univise on a surface grinder, when I want to be fussy. I
    haven't seen a Baldor carbide grinder for less than $600.


    Diamond wheels are available for a lot of things. Yes, you can freehand
    grind on a diamond wheel. A buddy of mine sells tungsten grinding kits
    for various grinders that include adapters, and a cheap diamond coated
    wheel he buys in bulk from China. He sells them to welders for shaping tungsten electrodes. I have one of his cheap wheels and I sometimes use
    it to rough finish the edge on a tool before honing on a bench stone or
    lapping stick.

    I have a whole bucket (smallish) of broken and worn out carbide mills I
    save for making specialty tools. When I needed a special 7 degree
    dovetail cutter to make a tool holder I ground one of an old carbide end
    mill. Okay. I cheated. I cut the 7 degree cutting edge on a tool and
    cutter grinder with a diamond wheel, but other edges and clearances I
    just ground freehand.


    --
    Bob La Londe
    CNC Molds N Stuff


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  • From Bob La Londe@21:1/5 to David Billington on Tue Aug 20 11:23:19 2024
    On 8/20/2024 8:48 AM, David Billington wrote:
    On 20/08/2024 07:50, Charlie+ wrote:
    On Sun, 18 Aug 2024 17:02:31 -0700, Bob La Londe <none@none.com99> wrote
    as underneath :

    On 7/30/2024 2:44 PM, Richard Smith wrote:
    Bob La Londe <none@none.com99> writes:

    On 7/29/2024 11:38 PM, Richard Smith wrote:
    I heard diamond
    * works for Ali because it has no solubility for Carbon
    * does not work for irons/steels because the hard tool
    "disappears" by
         solution into the iron
    ?
    My apologies.  I didn't at all mean something like a PVD diamond
    coating.  DCMT is a diamond shaped insert.  Typically your find them >>>>> coated with TiN, uncoated, and occasionally with TiAlN or AlTiN
    coatings.  My point was these small geometry inserts that work so well >>>>> in under power under-rigid machines like the typical import 7-8 by
    10-16 mini lathe also work on a heavier machine.  If the big boy
    inserts don't work these still do.  In this case I was cutting 304
    stainless steel. It improved the finish, didn't require sharpening,
    had less heat input, and did the job much faster net elapsed time.

    FYI:  I do a fair amount of aluminum cutting, and generally I've found >>>>> bright sharp uncoated tools do the best job and have the best material >>>>> removal rate for me and leave a good finish.  Diamond was popular when >>>>> I first started cutting aluminum on machine tools, and more recently >>>>> ZrN has become the popular coating.  I've tried them and the simple >>>>> fact is a coated tool isn't as sharp.  They might work better for
    larger tools on larger machines, but on middle weight machines with
    limited horsepower (5 or less) a bright sharp uncoated tool works best >>>>> for me. For high speed flood coolant makes the tool last without chip >>>>> welding, but coatings do not.  On smaller tools horsepower isn't even >>>>> a factor as the tool can't take it anyway.


    --
    Bob La Londe
    CNC Molds N Stuff
    Thx for this detail.
    Interesting yes certainly.
    Sorry "got the wrong end of the stick".

    I used cutting insert tooling - aagh - 30 years ago.
    Vertical milling shell-cutter on steel.
    Did well - they'd never seen steel chip ejection like a chain-saw
    cutting timber.  Took a visit from the rep. who explained this is how >>>> the tooling is supposed to be used :-)
    Coated carbide inserts - coating the gold coloured one - a Ti
    nitride(?)
    coating - for this steel.

    Pushing it harder and harder.  As I once offended Jim a little (sorry
    Jim) over... time is money.  Even if you are doing something for fun,
    favor, self... time is still your most valuable nonrenewable resource.

    I needed to make another batch of stainless mold cores today.  (Stock
    design that uses upto nine (9) 1.5in diameter cores to varY the size of
    the casting.  That's 18 cuts to true them up after they come off the
    saw.

    My new inserts arrived a few days ago ago, but I wantedif I could bump
    up the speed a bit with that little hobby lathe size insert.  I had been >>> using at at 300 RPM in low gear.  That's a starting SFM of 117 if I have >>> done the math right.  I am sure there are folks pushing big turning
    centers orders of magnitude faster, but this is after all only a bigger
    import lathe.  Its still an import lathe, and while its relatively
    heavy, its light for its size.

    Of course the SFM drops as the diameter is reduced.  Maybe I could go
    faster if I cranked up the speed as I reduced the diameter, but this is
    a single phase gear head lathe.  The motor just turns one speed.  The
    time to stop it and change gears would eat up any time savings.

    Just for the heck of it I decided to see how much faster I could start.
    At 460 RPM the insert was still doing fine.  Still using the same insert >>> I used when I started this thread.  I don't mean the same type.  I mean >>> the same insert.  That means the insert was hitting the outside of the
    stock at 180 SFM.  The number doesn't sound much bigger, but the part
    time was definitely faster.

    A couple ends with an intact insert at that speed and I decided to try
    the last couple parts at 755 RPM.  296 SFM.  That was significantly
    faster.  Part time was a lot shorter, and the insert still looks like
    when I started.  (I'll look at under magnification later)  It wasn't so >>> fast that I had any issue keeping up, but it was fast enough I couldn't
    do anything else, like move the stock in the saw to cut the next rough
    blank.

    Now that I have spares I think next time I cut a batch of these cores I
    am going to push it until I chip an insert to see just what they will
    do.

    Please bare in mind that these are relatively light cuts.  The blanks
    come off the saw at about 1.4" to 1.41" and get trued to 1.375".

    Interesting thread Bob, thanks, is this example the type of tool you are
    talking about? Never come across the diamond tipped versions of inserts
    but my original machining in industry experience was in the 1960's! Only
    hobby level now..
    https://www.ebay.co.uk/itm/115334715488?_nkw=diamond+inserts+carbide+lathe&itmmeta=01J5Q723XNA0GREWTN8RFZEQK2&hash=item1ada7c1860:g:YyUAAOSwUtJiUKWN&itmprp=enc%3AAQAJAAAA4HoV3kP08IDx%2BKZ9MfhVJKnC8gu8jBQODZUzjY6nfSpuZas%
    2FJzGcWIYLgG5EPfxVgG0wH1c4QdrYrUHqD4z98NSE8atbz28SHAAsTTB%2FvXsdw1KSXcN7%2Bx6cwyg%2FcKXwvDq3eEqXZbpx%2Bzxtc0f0%2Fp0BsyoIUtnlZlJQI86p6TyhETkaZsGuuwYw1Ayo2CHAORe6WE1WiaDElO8xogeQY1mItmsxVxjRLhavW15vEW5hMGkyR8srWzmxrGq4dX%2B9yZ23zhsDDiiDdifsQ%2Bk8r7IRPefZ9T%
    2FppdLbpKF%2FwpjM%7Ctkp%3ABk9SR_S-iOetZA
    It says for non ferrous but you are using on stainless without any red
    spark? Can they be touched up if/when the edge goes?  I know its only a
    single but looks uncheap to me!  C+

    If you read Bob's post 30/7/2024 he clarifies he's not talking about
    diamond tipped inserts but diamond shaped rhombic inserts.



    That's true, but I did run across a reference (Stefan Gotteswinter video
    maybe) to an actual diamond attached to a tool. There are also coatings
    that are called diamond, although most are actually DLC "diamond like coatings."


    --
    Bob La Londe
    CNC Molds N Stuff


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  • From Peter Fairbrother@21:1/5 to Bob La Londe on Tue Aug 20 22:27:38 2024
    On 20/08/2024 19:23, Bob La Londe wrote:

    That's true, but I did run across a reference (Stefan Gotteswinter video maybe) to an actual diamond attached to a tool.

    PCD diamond turning inserts are actually quite common. They are mostly
    made from natural diamonds, sometimes synthetic. There is another kind
    whose name I have forgotten which is even more diamond-y, though still
    not a single diamond.


    PCD inserts (or better CBN ones if machining steels) made for aluminium
    can be of use to hobby people if careful; being sharper then ones made
    for harder stuff they will cut with less force, useful on smaller less
    powerful machines.

    Recommended only once you have learned how to use inserts without
    chipping them!



    SPD single point diamond turning tools (which are single diamonds) are
    often used in CNC machines for optical moulds and lenses. The finish is
    used as-is, no polishing!!!

    Sometimes used for high-accuracy machining of copper and copper alloys too.

    When air bearings aren't smooth enough ..

    https://www.youtube.com/watch?v=5tQd5RVCriI



    I have a 1/2 carat single diamond tool for truing grinding wheels. Cost
    about £!5 iirc, but that was a while ago. Hmm, still £14.99 on ebay.


    There are also coatings that are called diamond, although most are
    actually DLC "diamond like coatings."


    CVD chemical vapour deposition diamonds are frequently grown on tooling surfaces; they are real diamonds, though not single diamonds when grown
    on surfaces.

    They are sometimes made into blocks in a nickel or cobalt matrix, as
    found on circular saw blades and polishing disks, though often natural
    diamonds are cheaper.



    Peter Fairbrother

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  • From Charlie+@21:1/5 to All on Wed Aug 21 07:06:50 2024
    On Tue, 20 Aug 2024 16:48:55 +0100, David Billington <djb@invalid.com>
    wrote as underneath :

    On 20/08/2024 07:50, Charlie+ wrote:
    On Sun, 18 Aug 2024 17:02:31 -0700, Bob La Londe <none@none.com99> wrote
    as underneath :

    On 7/30/2024 2:44 PM, Richard Smith wrote:
    Bob La Londe <none@none.com99> writes:

    On 7/29/2024 11:38 PM, Richard Smith wrote:
    I heard diamond
    * works for Ali because it has no solubility for Carbon
    * does not work for irons/steels because the hard tool "disappears" by >>>>>> solution into the iron
    ?
    My apologies. I didn't at all mean something like a PVD diamond
    coating. DCMT is a diamond shaped insert. Typically your find them >>>>> coated with TiN, uncoated, and occasionally with TiAlN or AlTiN
    coatings. My point was these small geometry inserts that work so well >>>>> in under power under-rigid machines like the typical import 7-8 by
    10-16 mini lathe also work on a heavier machine. If the big boy
    inserts don't work these still do. In this case I was cutting 304
    stainless steel. It improved the finish, didn't require sharpening,
    had less heat input, and did the job much faster net elapsed time.

    FYI: I do a fair amount of aluminum cutting, and generally I've found >>>>> bright sharp uncoated tools do the best job and have the best material >>>>> removal rate for me and leave a good finish. Diamond was popular when >>>>> I first started cutting aluminum on machine tools, and more recently >>>>> ZrN has become the popular coating. I've tried them and the simple
    fact is a coated tool isn't as sharp. They might work better for
    larger tools on larger machines, but on middle weight machines with
    limited horsepower (5 or less) a bright sharp uncoated tool works best >>>>> for me. For high speed flood coolant makes the tool last without chip >>>>> welding, but coatings do not. On smaller tools horsepower isn't even >>>>> a factor as the tool can't take it anyway.


    --
    Bob La Londe
    CNC Molds N Stuff
    Thx for this detail.
    Interesting yes certainly.
    Sorry "got the wrong end of the stick".

    I used cutting insert tooling - aagh - 30 years ago.
    Vertical milling shell-cutter on steel.
    Did well - they'd never seen steel chip ejection like a chain-saw
    cutting timber. Took a visit from the rep. who explained this is how
    the tooling is supposed to be used :-)
    Coated carbide inserts - coating the gold coloured one - a Ti nitride(?) >>>> coating - for this steel.

    Pushing it harder and harder. As I once offended Jim a little (sorry
    Jim) over... time is money. Even if you are doing something for fun,
    favor, self... time is still your most valuable nonrenewable resource.

    I needed to make another batch of stainless mold cores today. (Stock
    design that uses upto nine (9) 1.5in diameter cores to varY the size of
    the casting. That's 18 cuts to true them up after they come off the saw. >>>
    My new inserts arrived a few days ago ago, but I wantedif I could bump
    up the speed a bit with that little hobby lathe size insert. I had been >>> using at at 300 RPM in low gear. That's a starting SFM of 117 if I have >>> done the math right. I am sure there are folks pushing big turning
    centers orders of magnitude faster, but this is after all only a bigger
    import lathe. Its still an import lathe, and while its relatively
    heavy, its light for its size.

    Of course the SFM drops as the diameter is reduced. Maybe I could go
    faster if I cranked up the speed as I reduced the diameter, but this is
    a single phase gear head lathe. The motor just turns one speed. The
    time to stop it and change gears would eat up any time savings.

    Just for the heck of it I decided to see how much faster I could start.
    At 460 RPM the insert was still doing fine. Still using the same insert >>> I used when I started this thread. I don't mean the same type. I mean
    the same insert. That means the insert was hitting the outside of the
    stock at 180 SFM. The number doesn't sound much bigger, but the part
    time was definitely faster.

    A couple ends with an intact insert at that speed and I decided to try
    the last couple parts at 755 RPM. 296 SFM. That was significantly
    faster. Part time was a lot shorter, and the insert still looks like
    when I started. (I'll look at under magnification later) It wasn't so
    fast that I had any issue keeping up, but it was fast enough I couldn't
    do anything else, like move the stock in the saw to cut the next rough
    blank.

    Now that I have spares I think next time I cut a batch of these cores I
    am going to push it until I chip an insert to see just what they will do. >>>
    Please bare in mind that these are relatively light cuts. The blanks
    come off the saw at about 1.4" to 1.41" and get trued to 1.375".

    Interesting thread Bob, thanks, is this example the type of tool you are
    talking about? Never come across the diamond tipped versions of inserts
    but my original machining in industry experience was in the 1960's! Only
    hobby level now..
    https://www.ebay.co.uk/itm/115334715488?_nkw=diamond+inserts+carbide+lathe&itmmeta=01J5Q723XNA0GREWTN8RFZEQK2&hash=item1ada7c1860:g:YyUAAOSwUtJiUKWN&itmprp=enc%3AAQAJAAAA4HoV3kP08IDx%2BKZ9MfhVJKnC8gu8jBQODZUzjY6nfSpuZas%
    2FJzGcWIYLgG5EPfxVgG0wH1c4QdrYrUHqD4z98NSE8atbz28SHAAsTTB%2FvXsdw1KSXcN7%2Bx6cwyg%2FcKXwvDq3eEqXZbpx%2Bzxtc0f0%2Fp0BsyoIUtnlZlJQI86p6TyhETkaZsGuuwYw1Ayo2CHAORe6WE1WiaDElO8xogeQY1mItmsxVxjRLhavW15vEW5hMGkyR8srWzmxrGq4dX%2B9yZ23zhsDDiiDdifsQ%2Bk8r7IRPefZ9T%
    2FppdLbpKF%2FwpjM%7Ctkp%3ABk9SR_S-iOetZA
    It says for non ferrous but you are using on stainless without any red
    spark? Can they be touched up if/when the edge goes? I know its only a
    single but looks uncheap to me! C+

    If you read Bob's post 30/7/2024 he clarifies he's not talking about
    diamond tipped inserts but diamond shaped rhombic inserts.

    Thanks David, I re-read that post but have never come across the inserts
    he is talking about so I was looking for a link to clarify myself! C+

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  • From Charlie+@21:1/5 to All on Wed Aug 21 07:19:20 2024
    On Tue, 20 Aug 2024 18:17:05 +0100, Peter Fairbrother <peter@tsto.co.uk>
    wrote as underneath :

    On 20/08/2024 07:50, Charlie+ wrote:

    [...]
    Only hobby level now..
    https://www.ebay.co.uk/itm/115334715488?_nkw=diamond+inserts+carbide+lathe&itmmeta=01J5Q723XNA0GREWTN8RFZEQK2&hash=item1ada7c1860:g:YyUAAOSwUtJiUKWN&itmprp=enc%3AAQAJAAAA4HoV3kP08IDx%2BKZ9MfhVJKnC8gu8jBQODZUzjY6nfSpuZas%
    2FJzGcWIYLgG5EPfxVgG0wH1c4QdrYrUHqD4z98NSE8atbz28SHAAsTTB%2FvXsdw1KSXcN7%2Bx6cwyg%2FcKXwvDq3eEqXZbpx%2Bzxtc0f0%2Fp0BsyoIUtnlZlJQI86p6TyhETkaZsGuuwYw1Ayo2CHAORe6WE1WiaDElO8xogeQY1mItmsxVxjRLhavW15vEW5hMGkyR8srWzmxrGq4dX%2B9yZ23zhsDDiiDdifsQ%2Bk8r7IRPefZ9T%
    2FppdLbpKF%2FwpjM%7Ctkp%3ABk9SR_S-iOetZA

    Those are PCD polycrystalline diamond tipped inserts. Diamond crystals
    in a cobalt alloy matrix. For very hard materials sometimes, but far
    more often for extreme wear resistance.

    It says for non ferrous [..]
    The carbon in the diamond dissolves in iron and steel (and nickel
    alloys), so they don't last long on steel. You can use CBN cubic boron >nitride on steel etc for longer life, about the same price.

    Hobby level chaps (and most small-batch pros, indeed most pros) should >generally stick to HSS or carbide, unless they are doing something unusual.

    Can they be touched up if/when the edge goes?

    No. Carbide inserts can sometimes be touched up with diamond (though
    it's usually not worth doing unless you want something special), but not
    PCD or CBN.

    I know its only a single but looks uncheap to me! C+

    Last time I bought any they were ú20-odd each, and that was years ago.


    Peter Fairbrother

    Thanks Peter for all the detail, I'm better informed now, aprecciated.
    C+

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