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  • How’d I do (grinding bits)?

    I have been grinding bits for a year now, and I think I’m finally starting to get the hang of it. With that in mind I think it’s time to bite the bullet, see what some of the masters think.

    This is a finisher bit I ground for an upcoming stainless project. After shaping it on the 6” grinder I hand honed it with a 325 grit diamond hone.

    So what do you think any good?



    -Dan S.
    dans-hobbies.com

  • #2
    Looks good to me. Next question is whose tool steel are you using?
    Free software for calculating bolt circles and similar: Click Here

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    • #3
      Dan, what kind of a hone do you use and what is that depression back from the cutting edge on the top?

      Comment


      • #4
        Looks good but the real test is how it cuts. If it cuts well, it is a good grind and if it doesn't, then back to the grinding wheel.

        Of course, I am not a real expert, just a grinding fool.

        Paul A.
        Paul A.
        SE Texas

        Make it fit.
        You can't win and there is a penalty for trying!

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        • #5
          The grinding looks good. Plus the honed edge should make a nice cut.

          What size is the nose radius? It looks fairly large. Is your lathe rigid enough for the radius?

          I assume the circular depression on the top is meant as a chip breaker, right? If so, it may be too far from the cutting edge to be effective.

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          • #6
            In many cases for lightweight home shop machines you can throw out the standard specs for cutting tools. Best results are often obtained with high rake tools in many materials including steel (not brass though). It requires much less horspower and produces much lower cutting forces reducing the possibility of chatter. The edges don't last as long but that isn't a big issue when you grind your own.
            Free software for calculating bolt circles and similar: Click Here

            Comment


            • #7
              Evan,

              Mo-Max M-42 cobalt, so it could be made in America or Mexico.

              Mike,

              I have a set of the DMT Credit Card hones. They are cheap, and I don’t think I will need anything bigger for tool bits.

              The depression is from grinding. Grinding on the peripheral of the wheel, this causes the faces to be slightly dished. Honing the bit starts to flatten the face, thus giving it the appearance above.

              DR,

              The nose radius is 3/32” (I think, I would have to see what I wrote down when I get home). My lathes not massive, but for finishing cuts (<.01) I can use a nose radius of this size. The depression is from grinding on the wheel peripheral.

              Eventually I want to make a tool grinder, because as much as I like the end results, I never look forward to using the bench grinder. I find it tedious and some what time consuming.
              -Dan S.
              dans-hobbies.com

              Comment


              • #8
                <sigh>
                Said it before, I'll say it again.
                0 rake, HSS (plain old vanilla)
                flood suds, soluble oil/water
                Jet 9x20 lathe
                lots of 316 been through that little machine!
                Here's a pic, sorry about the crap quality but the only cam I have is my phone.
                Finish is acceptable straight off the tool. If any clean up needed, it's scotchbrite green.
                Just got my head together
                now my body's falling apart

                Comment


                • #9
                  Originally posted by dan s
                  Eventually I want to make a tool grinder, because as much as I like the end results, I never look forward to using the bench grinder. I find it tedious and some what time consuming.
                  Tedious and time consuming, wait until you try to set up a t&c grinder to do all those angles! Hand held on a bench grinder with a fast cutting, dressed wheel is the way to go. There is NO precision required on these angles, so do away with fancy jigs and fixtures (yeah i built em too when i was newb, they're good for only one thing, sitting in a drawer). check with a protractor when you are learning, but that won't last more than a couple of grinds

                  The t&C is good for threading tools where precise angles matter, but there is no point for regular cutting tools. if the bench grinder is frustrating, maybe you're using one of the crappy grey wheels that came with it? I bought an 8" delta ten years ago, put one of the ruby wheels on it and keep it dressed. I'll probably still be on the same wheel ten years from now, and its hard to spend a complete minute grinding a tool bit.

                  it looks like you did a good job on the tool bit, I put a lot less of a radius on, but then again I never caught on to that really big radius, fast feed finishing tool shown in the text books. maybe i should retry it.
                  Last edited by Mcgyver; 04-11-2007, 12:25 PM.
                  .

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                  • #10
                    Amen, McGyver!
                    Just got my head together
                    now my body's falling apart

                    Comment


                    • #11
                      Yep, it's all about the wheels. I have a 10" diamond wheel that I run at low speed and it will grind the toughest carbide as if it were mild steel. You need the right wheel for the job.
                      Free software for calculating bolt circles and similar: Click Here

                      Comment


                      • #12
                        Mcgyver,

                        You touched on part of the issue I’m Having. I’m using white wheels currently; while they give an excellent finish, the stock removal rate leaves much to be desired. I need to learn more about wheels, because I will need some new wheels soon, and I want some that will remove stock faster.

                        With regard to angles, I can see a difference in surface finish when I change tool rake (though this could be a newb reading to much into things). I’m also overly meticulous. For example ask me what pie is; 4*ATAN(1).

                        My current set up looks something similar to this.

                        http://homepage3.nifty.com/amigos/gr...ing_rest-e.htm
                        -Dan S.
                        dans-hobbies.com

                        Comment


                        • #13
                          Dan, if you want to worry about angles etc, concentrate more on your drills.
                          Maybe I'm just lackadaisical, but a cheap 6" bench grinder with the standard tool-rest works fine for me.
                          As I've said before, I just grind 0 top rake (grind end of steel only) and finish up with a diamond hone.
                          Just got my head together
                          now my body's falling apart

                          Comment


                          • #14
                            Originally posted by dan s
                            With regard to angles, I can see a difference in surface finish when I change tool rake (though this could be a newb reading to much into things). I’m also overly meticulous. For example ask me what pie is; 4*ATAN(1).

                            My current set up looks something similar to this.
                            to clarify, by accuracy I meant like 12 degrees vs 14 degrees not 5 vs 25 for example and you'll get good at judging it by eye - if you're getting a noticably better finish because of a degree or two, you've a better eye than I or there are other variables at play. I built a similair rest and imo it is usefull for one thing, providing a straight edge across which to drag the holder of the diamond dresser
                            .

                            Comment


                            • #15
                              Originally posted by Mike W
                              Dan, what kind of a hone do you use and what is that depression back from the cutting edge on the top?
                              That looks like a reflection or a drop of water.

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