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  • carbide tool sharpening

    Greetings to all--
    I've read the many posts here about sharpening ones own cutting tools-- With carbide being so hard, what do you use to sharpen it? Is there a guide telling what angles to cut for which uses? Appreciate all of your help--
    Best regards, Ron



    On the other hand, we have, the other hand--

  • #2
    Diamonds are a machinists best friend...

    there are general rules of thumb for angles for different aplications and thats a good starting place --- then venture off a little and see what works best for your particular machine and material...

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    • #3
      Hi,Ron,the poor man's way to sharpen carbide is with a green wheel(silicon carbide)these wheels are inexpensive,but they wear down quick in use and are best suited for free-hand sharpening as they don't maintain an accurate shape very long.

      The best choice are diamond wheels and coolant,they used to be super expensive,but now thanks to Ebay and imports coming in they can be had reasonable.They wear down very slowly especially with coolant and will last for years.Homeshop use just a cool-mist gun will be enough,or failing that a can of coolant and a drip feed to the wheel.

      One word of warning however,carbide dust is a lung irritant and the cobalt binders used in some carbide is toxic.It's best to do your sharpening wet with coolant.At a bare minimum if you do grind dry wear a good quality filter mask.

      Hope this helps.
      I just need one more tool,just one!

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      • #4
        Originally posted by wierdscience
        One word of warning however,carbide dust is a lung irritant and the cobalt binders used in some carbide is toxic.It's best to do your sharpening wet with coolant.At a bare minimum if you do grind dry wear a good quality filter mask.
        Thanks Wierd, I was not aware of that and didn't think you'd make enough dust to matter. Maybe it's time to replace my air mask.
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        • #5
          The right way to sharpen carbide is with a diamond wheel. The green silicon carbide wheels will do the job, sorta, but the resulting edge is not as good.
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          • #6
            Originally posted by Your Old Dog
            Thanks Wierd, I was not aware of that and didn't think you'd make enough dust to matter. Maybe it's time to replace my air mask.


            I havent sharpend much carbide at all but at my friends shop he has a great little diamond sharpener for carbide that has all the angle adjustments, is pob. only a 6" wheel and it rotates really really slow, he sharpens dry and i really cant see a whole lot wrong with that because it doesnt stir anything up in the air...

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            • #7
              The low rpm grinders will let you use diamonds on HSS as well as carbide (high speed diamond grinding of HSS will eat the diamond, high speed carbide grinding is fine). Often these grinders can be found as 'lapping' machines.

              Glendo makes the Accu-finish, you may have seen their adverts in magazines. They have a couple of models, the larger has wheels starting at 360 grit and ending up at 1200 grit as well as a ceramic lapping plate that you can run with finer diamonds.

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              • #8
                I think it was Forrest Addy who posted some time back that the green wheels leave a chipped edge on carbide, and I would say that my own experience shows this to be true.

                I have used one of the slow speed grinders to sharpen carbide scraper blades and it is a real treat. You wet the wheel with kerosene, and with the table set to the correct angles, gently "wipe" the carbide past the wheel. It runs slow enough that you have good control and are not apt to grind away more of your carbide than you need to. This is especially nice for something like scraper blades where you are freehanding a gentle curve, which doesn't make for easy use of a jig to hold the work.

                I have also used a higher speed carbide grinder with a diamond wheel and it takes a lot of care to avoid wasting carbide.

                I hope some day to mount a diamond wheel on my tool and cutter grinder and use that...so I don't have to grind mounted carbide freehand. It beats buying yet another grinder to eat up space I don't have.

                As Evan has pointed out, carbon is a solvent for diamonds which are also carbon....so using your expensive diamond products on sharpening steel is probably wasteful. Steel sharpens well with other abraisives anyway.

                Paul
                Paul Carpenter
                Mapleton, IL

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                • #9
                  Good greetings to all--
                  Thanks so much for the helpful info-- The more I get into this, the more I find I don't know-- AK-- Where can I find the info on cutter angles/uses? W/S-- Good to know about the dust and cobalt factor-- Seems there is a lot more to do you harm than the cutters, spinning equip. etc--
                  Best regards, Ron



                  On the other hand, we have, the other hand--

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                  • #10
                    Originally posted by pcarpenter
                    I think it was Forrest Addy who posted some time back that the green wheels leave a chipped edge on carbide, and I would say that my own experience shows this to be true.
                    Likewise -- if you look at the carbide edge under a loop or magnifying glass after you've sharpened it with a Silicon Carbide wheel, there are a bunch of fracture inclusions, almost like the SiC is tearing the carbide instead of shearing it.

                    The cheap EZ-Laps are great, as are the credit-card sized diamond laps that the usual suspects sell.

                    On the other hand, for the amound of time it takes to hand re-sharpen carbide bits, it's hard to beat the $120 Horror Freight Baldor clone with a $75 ebay diamond wheel...
                    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                    • #11
                      Originally posted by A.K. Boomer
                      I havent sharpend much carbide at all but at my friends shop he has a great little diamond sharpener for carbide that has all the angle adjustments, is pob. only a 6" wheel and it rotates really really slow, he sharpens dry and i really cant see a whole lot wrong with that because it doesnt stir anything up in the air...
                      Just curious, but what is "slow"? Got a rough idea on SFPM or RPM? I really need a better sharpening system better than just hand sharpening. It's such a pain that I have several times compromised my work by convincing myself that it's "good enough for a bit more" rather than stop to fix it (particularly when fly cutting). I’ve been looking at various grinders at auction, but passed because it seemed like junk or too pricey. I’ve agonized over a HF tool grinder, or pay a bit more for an auction Baldor (once in a while they sell for reasonable, but often $300+ without wheels!). And I really don't have space for yet another tool. I've been told that a belt sander works well too, but I guess my AO belts aren't up to the task. Maybe a 1 or 2" 220 SO belt would do the trick? That would be ideal since I wouldn't need space allocated to another machine. I don't mind final tuning with a fine diamond lap, but actually modifying and edge is a major hassle...
                      Russ
                      Master Floor Sweeper

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                      • #12
                        For those that dont know.Rough the botton of your brazed on carbide bit with a standard alun. oxide wheel grinding the steel off at the requird angle then useing a green wheel grind the whole side carbide and steel till carbide edge is formed, then touch the carbide part only at a 1-2 degree lesser angle to a diamond wheel for the final edge.
                        Last edited by lane; 11-15-2006, 07:54 PM.
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                        • #13
                          If you don't have room for another machine,then make an attachment for an existing one.
                          I just need one more tool,just one!

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                          • #14
                            Such as? I've been puttering around with ideas (and collecting parts) for a sort of supercharged rendition of the KMG belt grinder with added spindles. But sounds like you've got some ideas? My main thing is that I don't want to be forced to remount/retrue wheels all the time. So replaceable arbors should cover that, though coming up with a "quick change" that I like is still eluding me.

                            Also, what do you guys think about the SO belts, will they work to sharpen carbide tooling? If so, that seems ideal...
                            Russ
                            Master Floor Sweeper

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                            • #15
                              Originally posted by BadDog
                              Such as? I've been puttering around with ideas (and collecting parts) for a sort of supercharged rendition of the KMG belt grinder with added spindles. But sounds like you've got some ideas? My main thing is that I don't want to be forced to remount/retrue wheels all the time. So replaceable arbors should cover that, though coming up with a "quick change" that I like is still eluding me.

                              Also, what do you guys think about the SO belts, will they work to sharpen carbide tooling? If so, that seems ideal...
                              You could make up a spindle to accept grinding wheel arbors like surface grinders use.The wheel is mounted to a stub arbor that has a female taper in it that is held on the spindle with a nut.These can be had off Ebay reasonable enough.You can leave the wheels mounted on the arbors and just swap them at will without having to re-dress.

                              If a person has a lathe a pulley can be mounted on a stub shaft and chucked in the three jaw.It can be used to drive things mounted to the ways or a purpose built bracket using the lathe for power.
                              I just need one more tool,just one!

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