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Brazed carbide tool bit question.

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  • Brazed carbide tool bit question.

    I need a tap for the weekend so I went on McMaster so I know it will be here. While on there I figured would pick up a new cutting tool for the job as well. This was the statement in the description for the tool bit "These tools need to be sharpened before use and whenever they dull."

    This is a standard C6 brazed on carbide cutter. Has anyone had to sharpen these when new? Any of the ones I ever used usually had a wax/rubber coating on the tip and were ready to go. I am not setup to grind carbide in the shop yet or I would grind one of the many dull ones I have sitting in the drawer

  • #2
    All the imports need ground and a lot of the higher end ones need more back clearance, depending on the application. You don't need a diamond wheel, just a green wheel works fine.


    • #3
      This might be a newer sort of cost cutting step. In the past the brased tool bits with the wax coating I bought were ready to use.

      If you're shopping with McM's anyway pick up a green silicon carbide wheel to use with your brazed toolbits? Then you can sharpen up the old ones.

      A diamond wheel for finishing would be nice. But a nice compromise is a green wheel for shaping and getting the initial edge and a fine grade hand held diamond file or slip stone to give the final edge that resists breaking down if cutting harder materials.


      • #4
        I know, the green wheel has been on the list of things to get for too long. What grit to get for it?


        • #5
          I have several NOS brazed carbide bits that came from the UK, they came with the whole tool painted, so I would expect to have to hone them before use. I would avoid grinding them with a green wheel, and just hone them with diamond stones.

          I have read that the green wheels tend to leave the edge with micro cracks, and you should hone with a diamond stone anyway.


          • #6
            If you go for the diamond hone I'd suggest something not too fine since it'll mostly be used for shaping and cutting back to remove chipped corners.

            Hint, I found that if I had to grind it back to remove a chip that the softer shank metal really wears the stone fast. so I tend to grind away a little of the shank first on a regular grinder and use the green stone as much as practical for only the carbide portion..... it helps having a narrow side bench with three grinders on it....


            • #7
              I recently bought some of these tool bits from KBC. Since the USA ones were mixed in with the cheap import ones on the same catalog page I ended up with the cheap imports.
              The entire tool bit was painted for one thing. When I cleaned the paint off of one I noticed the shank sides were slightly crowned. I was about to grind one flat on the bottom but then noticed how off center the brazed insert was, not to mention it was dull.
              I called KBC and told them how poor these were and that I couldn't use them. They replaced them with the USA made ones that were much better all the way around.
              The carbide was properly centered, it wasn't dead sharp but would have been OK for rough work. I had to dress it a bit with a diamond wheel to get the edge I wanted.
              I have much better luck with inserts.



              • #8
                Originally posted by Toolguy View Post
                All the imports need ground and a lot of the higher end ones need more back clearance, depending on the application. You don't need a diamond wheel, just a green wheel works fine.
                +1. Brazed bits always need to be shaped and sharpened before use. I don't think in 28 years i've ever peeled off the wax to find a usable edge, no matter where they came from.