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  • From: Lawrence London <lfljvenaura@gmail.com>
  • To: machinist@lists.ibiblio.org
  • Subject: [machinist] Disk sander for shaping carbide? - good thread on carbide tooling & sharpening it
  • Date: Wed, 26 Feb 2014 09:09:19 -0500

http://www.practicalmachinist.com/vb/general/disk-sander-shaping-carbide-280909/

Thread: Disk sander for shaping carbide?

  1. 02-25-2014, 11:46 PM #1
    bugman53 is offline Aluminum
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    Default Disk sander for shaping carbide?

    I am just a casual machinist, I have a south bend lathe in my motorcycle shop that I use for odd jobs we run it maybe once a week for a few hours. A lot of the time we are modifying fairly hard steel parts and some aluminum. I have been using brazed carbide bits from American carbide with a AXA QCTP. I would buy a tool grinder but it would take 50 years to pay for itself no more then we use.

    I have a few bits that have a dull edge and was thinking is it possible to grind them on my belt or disk sander? The disk sander is nice because I can set the table and guide to the angle I need. I tried to use a AO 220 grit 3m disk and it polished up the carbide a touch but barley removed any material before striping the grit off the disk. Has anyone tried an Silicon carbide PSA disk?
  2. 02-26-2014, 01:50 AM #2
    Mike C. is offline Diamond
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    Carbide is going to eat a sanding disc up and also the disc will give a radiused edge instead of a hard flat surface like you will get from a grinding wheel. Just get some green wheels for a bench grinder. It's not the ideal way to sharpen carbide (I like to liken it to sharpening your pocket knife on the sidewalk), but it is serviceable.

    Unless the parts you are modifying are truly hardened (induction hardened material, case hardened or nitrided), you can probably save yourself a lot of time and money by using High Speed Steel bits instead of carbide tooling. Especially on aluminum, you can't run a SB fast enough to justify carbide and the HS will not gum up as bad. Main thing is to know your speeds when it comes to cutting steel with HSS bits. You want to be running between 50 and 100fpm on the surface speed to avoid burning the tool up. You'll find your spindle speed is lower, but you can take a deeper bite and up the feed rate a LOT when using HSS versus carbide on a low powered lathe like a SB. You will take a lot longer per pass, but you can remove about eight times more metal per pass with HSS. You sharpen HSS on a plain old gray bench grinder wheel.
  3. 02-26-2014, 02:17 AM #3
    greenbuggy is offline Hot Rolled
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    If you insist on carbide, might try getting yourself a coarse steel-backed diamond wheel that you can put on a bench grinder to rough out your carbide tool and then you'll also need a smooth steel wheel (can make it easily enough yourself) that you can apply lapping paste to in order to polish your carbide to a shiny finish once you're past the roughing phase.

    You may also find it worthwhile to invest in a diamond embedded sharpening stone (I have one from Diamond Materials Technology that works pretty well) so that you can do minor sharpening on the machine without pulling the tool holder out.
  4. 02-26-2014, 03:05 AM #4
    tnmgcarbide's Avatar
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    my belt grinder works much better for grinding and touching up carbide tools and inserts(non-coated) than my pedestal grinder w/ a green wheel.
    i'll rough grind w/ a 60 grit SC belt ,and finish up w/ a 150 grit SC belt (on a 1.5hp Somaca wet/dry 106" x 4" machine w/ a flat platen ) .
    if you must use a green wheel , i'd suggest a 120 grit , and dress it often .
  5. 02-26-2014, 04:22 AM #5
    thermite is offline Diamond
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    Quote Originally Posted by bugman53 View Post
    I am just a casual machinist, I have a south bend lathe in my motorcycle shop that I use for odd jobs we run it maybe once a week for a few hours. A lot of the time we are modifying fairly hard steel parts and some aluminum. I have been using brazed carbide bits from American carbide with a AXA QCTP. I would buy a tool grinder but it would take 50 years to pay for itself no more then we use.

    I have a few bits that have a dull edge and was thinking is it possible to grind them on my belt or disk sander? The disk sander is nice because I can set the table and guide to the angle I need. I tried to use a AO 220 grit 3m disk and it polished up the carbide a touch but barley removed any material before striping the grit off the disk. Has anyone tried an Silicon carbide PSA disk?
    For rough shaping, on low/no budget, you'll get faster removal with some of the wheels available for common angle-grinders. Grinder can be grasped in a stout-enough vise or can be worm-gear clamped to a 2-by in turn Cee-clamped to the edge of the bench.

    But don't cite me as a source, please. It is a shade-tree technique if ever was.

    It DOES work if you are patient, have a good hand, but the result is pretty ugly unless you have a diamond-abrasive wheel to clean it up with afterwards.

    I have several such, of course.. But mostly just go and use HSS so as to not have to deal with carbide atall..



    Bill
  6. 02-26-2014, 04:30 AM #6
    Nick Mueller is offline Stainless
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    Tool up, buy inserts!


    Nick
  7. 02-26-2014, 04:53 AM #7
    Heavey Metal is online now Titanium
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    A diamond tile cutting wheel from the hardware store in a die grinder will put a razor edge on them.

    You can also get cermet inserts which will work fine on your toy lathe.
  8. 02-26-2014, 05:09 AM #8
    peterve's Avatar
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    Quote Originally Posted by Nick Mueller View Post
    Tool up, buy inserts!


    Nick
    On a south bend ???
    Come on
    Inserttooling cost more as the lathe

    Peter from holland
  9. 02-26-2014, 07:46 AM #9
    jamesu229 is online now Cast Iron
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    I would go with insert tooling, Can be bought for cheap on ebay. However, if you still want to grind, this is the way to go.
    6 x 3 8 x 1 1 4 inch D1A1 Diamond Wheel | eBay
    It would probably last you a lifetime. I use this brand, the binder does not break down like the premium wheels. You would just have to make an adapter to put it on a 6" grinder.
  10. 02-26-2014, 07:58 AM #10
    Gthphtm is online now Aluminum
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    Quote Originally Posted by jamesu229 View Post
    I would go with insert tooling, Can be bought for cheap on ebay. However, if you still want to grind, this is the way to go.
    6 x 3 8 x 1 1 4 inch D1A1 Diamond Wheel | eBay
    It would probably last you a lifetime. I use this brand, the binder does not break down like the premium wheels. You would just have to make an adapter to put it on a 6" grinder.
    What ever type of Diamond wheel you buy remember it should have some way of dripping or spraying water on it,Do Not grind on a Dry Diamond wheel.Not talking about cutoff wheels true grinding wheels.
  11. 02-26-2014, 08:17 AM #11
    thermite is offline Diamond
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    Quote Originally Posted by peterve View Post
    On a south bend ???
    Come on
    Inserttooling cost more as the lathe

    Peter from holland
    Nah. SB's are seriously overpriced, so ....
  12. 02-26-2014, 08:49 AM #12
    rbent is online now Cast Iron
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    Quote Originally Posted by peterve View Post
    On a south bend ???
    Come on
    Inserttooling cost more as the lathe

    Peter from holland

    Naaa, people really love them and spend lots of pretty pennies for them it seems like.

    If you want inserts, Curt at latheinserts.com sells some nice 'hobby lathe' kits that work very well and the aluminum inserts are great.

    HOBBY LATHE KIT



  • [machinist] Disk sander for shaping carbide? - good thread on carbide tooling & sharpening it, Lawrence London, 02/26/2014

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