where to get a hollow point (female) carbide dead center?
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    Default where to get a hollow point (female) carbide dead center?

    Where can I purchase or order a reasonably-priced MT2 hollow-point (female) carbide dead center (60 degree)?

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    Quote Originally Posted by ballen View Post
    Where can I purchase or order a reasonably-priced MT2 hollow-point (female) carbide dead center (60 degree)?
    You could contact these folks:

    Special Centers, Live Centers, Dead Centers - Riten Industries

    For "ordinarier" goods, I save a few bob by using Stark;

    Dead Centers | Dead Center Products | Dead Center

    But... "female" is a tough one. Think it through. Cemented Carbides are not famous for resisting expanding forces.

    A (nitride) hardened surface on "ball bearing alloy" (5XXX) is the more likely find, and as one nose-art option among several on a decent "live" centre, even so.

    Cheaper to wear it out, swap in a new one. "How hard can that be"?


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    What I need is shown on the second page of this catalog (first item). But the prices are not reasonable, so I am hoping that there is a less expensive source. As you can see from the cross-section, the carbide is enclosed by steel, so under compression not tension.

    https://www.karlbruckner.de/fileadmi...all_Studer.pdf

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    Maybe you need another "X" for 52100

    "ball bearing alloy" (5XXX)

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    Quote Originally Posted by ballen View Post
    What I need is shown on the second page of this catalog (first item). But the prices are not reasonable....
    Neither are the customers...


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    Not a full cone but for limited size on can braze or press a carbide drill or reamer bushing on a Morse taper stub and mock up a dead center.
    I have not seen catalog female carbide but have seen them made as specials.

    Yes some grinding may be required.

    Tungsten Carbide Press-Fit Drill Bushing, 0.236" ID, 1/2" OD, 3/4" Length | eBay

    Tungsten Carbide Press-Fit Drill Bushing, 1/2" ID, 3/4" OD, 1/4" Length | eBay

    CARBIDE DRILL BUSHING HEADLESS KENNAMETAL (C-2-3-3-3) | eBay

    For a very small female a centered carbide tool can be cut off and the center pressed or brazed into a taper shank stub.

    15/64" -(.2344) Solid Carbide Reamer, 3-1/8" Length, TRW | eBay

    Common catlog sets (steel) one can clamp the spin and make these run dead.
    MT2 Live Center Set Morse Taper 2MT Triple Bearing Lathe Medium Duty CNC 609728674212 | eBay

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    It used to be common to take a cutting tool that did not have a center to grind a point on the tool, then grind it between one or two female centers. the with the tool to needs (ground to size) grind off the point.
    So we had a number of female centers in grinding shops but I never saw one in a catalog.... and don't know who made them.
    Last edited by michiganbuck; 06-17-2019 at 05:12 PM.

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    Quote Originally Posted by michiganbuck View Post
    It used to be common to take a cutting tool that did not have a center to grind a point on the tool, then grind it between one or two female centers. the with the tool to needs (ground to size) grind off the point.
    So we had a number of female centers in grinding shops but I never saw on in a catalog.... and don't know who made them.
    They are common "enough" that folk know what they are. Just not AS common in Carbide.

    Funny part is that the seeker is one of the few among us who already has the uber-high-precision cylindrical grinder that makes it easier for him to fab his OWN than most any other PM member could do!


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    Hi Buck,

    Quote Originally Posted by michiganbuck View Post
    Not a full cone but for limited size on can braze or press a carbide drill or reamer bushing on a Morse taper stub and mock up a dead center.
    I didn't know that one could buy off-the-shelf TC bushings. Good to know.

    I like your idea about cutting off the end of a solid carbide tool that has a center mark already. I'll have a look in my collection of broken cutters to see if there is something suitable there.

    I currently use a MT2 drill chuck arbor when I need a hollow center. But experience is teaching me that having a significant difference in hardness between the center point and the center socket reduces the chances of smearing and galling and running off center. So a carbide hollow center would come in useful.

    Cheers,
    Bruce

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    Quote Originally Posted by ballen View Post
    I currently use a MT2 drill chuck arbor when I need a hollow center.
    ER20 on # 2 MT tail can be had.

    All you'd have to do is make-up a collection of Carbide bushings on yer grinder and swap in a new one now and then. Either just the bushing - or the whole shebang, final-ground after clamping.

    Cheap enough.

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    QT:[Funny part is that the seeker is one of the few among us who already has the uber-high-precision cylindrical grinder that makes it easier for him to fab his OWN than most any other PM member could do!]

    Agree it looks like Bruce has a nice shop..but still a good idea to pick some Pm guys minds to get ideas. Most great ideas are old-hat to someone.

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    Hi Buck,

    Quote Originally Posted by michiganbuck View Post
    Agree it looks like Bruce has a nice shop..but still a good idea to pick some Pm guys minds to get ideas. Most great ideas are old-hat to someone.
    Exactly. I have no qualifications or training as a machinist, and don't have much face-to-face contact with people who do. That's why I ask so many questions here. It really helps me to avoid stupid mistakes and find better ways.

    Coming back to the matter at hand... I would enjoy making a hollow carbide-point center, but don't think I have the correct tooling. Are these first molded and then diamond-ground? I am not yet set up for internal grinding, and don't have diamond tooling. So the best I can do on my own is to braze a pre-formed hollow center (from the back of some carbide tooling) into a steel MT2 shank and then regrind that shank if needed to "center" the pip.

    Bill: the carbide bushings don't have the correct form to be precision centers. I also don't like the idea of having these hanging out in an ER20 collet on the end of an MT2 shank. For rigidity and precision I'd like the center support as short and close to the tailstock as possible. Also, I don't like the idea of grinding grit and coolant filling up an ER collet and holder. Grinding is messy.

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    Quote Originally Posted by ballen View Post
    Bill: the carbide bushings don't have the correct form to be precision centers.
    Pretty good reason to grind them, yah?

    I also don't like the idea of having these hanging out in an ER20 collet on the end of an MT2 shank. For rigidity and precision I'd like the center support as short and close to the tailstock as possible.
    You must not have seen an ER20 (or even smaller...) on #2 MT, then? The Carbide would be INSIDE the collet, so there is hardly any difference in hang-out,

    Also, I don't like the idea of grinding grit and coolant filling up an ER collet and holder. Grinding is messy.
    One could use the sealed tribe, supply fluid to it, let it keep itself clean. But this isn't a built-in to the grinder. It's removable. Just pop it out and go rinse it when it needs that.

    The straight-shank ER20 are about $15. Those on #2MT can be had with nut (w/o collet) for under US$ 20, replaced periodically.

    Uber-precision ones do not cost the Earth, either. Collets are not terribly dear. You don't need a full "set", just one or few sizes - to hold your choice of Carbides.

    "Consumables" at those prices, all parts involved.

    Time and materials to make something - anything - instead?

    Bound to cost a multiple. And cost was your initial purple-button?

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    Quote Originally Posted by thermite View Post
    Pretty good reason to grind them, yah?
    As I wrote, I am not set up for inside grinding, and don't have diamond tooling. I am confident that getting a precision polished surface and angle on a small bit of carbide is not easy.

    You must not have seen an ER20 (or even smaller...) on #2 MT, then? The Carbide would be INSIDE the collet, so there is hardly any difference in hang-out
    ER20 collets are 32mm (1 1/4") long. I would prefer a hollow point center that sits closer to the MT2 if possible.

    This isn't a built-in to the grinder. It's removable. Just pop it out and go rinse it when it needs that.
    I think you're won me over. Basically I can take a bit of broken carbide tooling with a hollow center point in it, put that backwards in the collet chuck, and pop that into the tailstock. Not ideal, but total cost is $30-40 and it's easy to experiment.

    Let me see if I can find an MT2/ER20 where the ER20 sits very close to the mouth of the MT2.
    Last edited by ballen; 06-18-2019 at 05:42 PM.

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    Perhaps a #2 tap holder could be sacrificed and the start to making a female.
    1PCS MT2 -M10 TAP superior quality 2# Morse taper jacket, a connecting | eBay

    Steel 3.5'' Morse Taper 2# To Morse Taper 1# Taper Adapter Reducing Drill Sleeve | eBay

    A #2 sleeve bored and a female center something pressed, glued, brazed in:
    Woodstock Morse Taper Sleeve M2 - M3 D2748 769433427487 | eBay

    An expired carbide centered cutter set between centers and ground to press into a #2 sleeve.

    Carbide bushing glued, pressed, brazed into a #2 sleeve.

    Just thinking, Buck

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    Quote Originally Posted by michiganbuck View Post
    Perhaps...
    You got it!

    Already in the drawer. Even if not, 2 MT to 1 MT sleeve, shop-modified, is going to get you the lowest starting cost and least hang-out.

    ER 20 (or thereabouts - I just happen to traffic in that size and ER 40 as their sizes overlap..) perhaps the least work, given one selects an existing collet to fit whatever Carbide is suited.

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    Quote Originally Posted by ballen View Post
    I am not yet set up for internal grinding, and don't have diamond tooling.
    When you get or make an internal grinding attachment, small diamond-plated pins are pretty cheap. Almost as cheap as mounted AlO or SiC stones of similar size, if you find the right source. Just ensure your grinding attachment can take small diameter shanks. Over here, the typical shank diameters would be 3/32" (2.38mm), 1/8" (3.175mm) or 1/4" (6.35mm); in the rest of the world, 2.35mm, 3mm and 6mm. Pins with 6mm or 1/4" shanks are probably too big for this particular application.

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    Quote Originally Posted by michiganbuck View Post
    An expired carbide centered cutter set between centers and ground to press into a #2 sleeve.
    I would need a 300mm (12") diamond wheel to grind that, something that I don't have. The MT2 tap holder is a good idea, I did not know that they even existed.
    Last edited by ballen; 06-19-2019 at 12:14 AM.

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    Expensive but having a decent life are mandrel mounted diamond wheels used for carbide ID work and the like. About $40 USD and up in price.
    Diamond Wheels Mandrel Mounted 1/8 3/16 1/4 5/16 3/8 1/2 5/8 3/4 1 Inch Diameter, Internal Grinding.

    The tap holder may not hold a carbide bushing rock solid so might need to be fabricated to make it true and solid.

    The MT sleeve made for a certain straight shank drill size and made to press a shouldered carbide bushing may be the best idea.

    *This has a good looking center and could be set into a #2 MT shank.
    Straight Carbide Boring Bar Bore Inner Hole Drilling Turning Tools Extension Rod | eBay

    SHB20-6 Φ6 Small Bore Hole Turning Tool Holder Carbide Boring Bar High Quality | eBay

    SHB 20 - 4 20mm Φ4 Small bore inner hole turning tool holder carbide boring bar | eBay

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    Those solid carbide boring bars look like a perfect source of center holes. Thank you! I've ordered a 20mm diameter one with a 3mm through hole. If I put it at the workhead side, I can just clamp it in a 20mm collet. For the tailstock side I'll need to get creative, it's too big for an ER20 collet.


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