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Why won't this endmill sharpening idea work?

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  • Why won't this endmill sharpening idea work?

    I was setting up to drill the 5C fixture mounting plate for the endmill grinding device I'm building in another thread and I dope slapped myself and said: "Why dont'cha just mount a diamond wheel on an arbor in the mill and use the mill table to precisely move the endmill?" Sitting in my comfortable milling machine chair with my magnifying visor on, looking at the endmill under a strong light made it look dead easy to crank the y axis over and dress the
    end accurately. The 5C collet fixture holds the tool at the proper angles and indexes for 2, 3, or 4 flutes. The wheel shown here is just a mockup to show the concept.



    The wheel speeds mentioned on the Glendo sharpener thread say a 6" wheel is spun at 308 rpm...I assume to control heat and diamond degradation. The surface speed of the Glendo wheel would be about 480 FPM (if my math is correct) so if you convert that to one of these 1" wheels http://www.harborfreight.com/cpi/cta...emnumber=40551 you get roughly 1850 rpm, well within my X-3's capabilities. Yes, I know that's a cheap, crappy wheel but I'm just doing a "what-if" mental exercise. Other, larger wheels could be used to do the same thing with a corresponding drop in rpm to control surface speed.

    Anyhoo, let's say we mount the whole rig up in a big plastic storage tub and rig a pump to flow coolant onto the grinding process to wash all the dust safely into tub. To make it really slick, we could mount one of the webcam viewers mentioned in another thread for a closeup view of the process.

    Seems like it'd work well to me. Makes me want to sh!t can my original project and do this one. The only advantage in finishing the original project is I could sharpen a tool without having to stop and teardown an existing setup in the mill.
    Milton

    "Accuracy is the sum total of your compensating mistakes."

    "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

  • #2
    I can't think of any reason why it won't work. But I do have a couple of considerations after looking at your pictures.

    First, the wheel you have mounted looks very coarse. Perhaps an artifact of the photo, but wouldn't you want an extra fine wheel to produce a nice edge on the mill? You did say it was just for the photo, but I still want to know what kind of wheel you should use.

    Second, I assume that either the wheel or the tool is tilted to an angle to grind the proper relief on the edge. I would want to insure that the wheel's rotation would not be in a direction that would tend to wedge the tool under the wheel. It looks like you have it right in the photo, but I think it is worth mentioning for all who read this. With the HP available on a mill spindle, rotation the other way could result in a ruined mill and wheel.
    Paul A.
    SE Texas

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

    Comment


    • #3
      You're right Paul, that is a coarse wheel; I just stuck it in to show the idea.

      Good point about the wedging effect. Didn't think of that. So in the pic, the tool is leaning to the right 5 degrees and I was thinking the wheel should spin in reverse, counter-clockwise. Is that correct?
      Last edited by DICKEYBIRD; 05-11-2008, 01:07 PM.
      Milton

      "Accuracy is the sum total of your compensating mistakes."

      "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

      Comment


      • #4
        Like he said,"The wheel shown here is just a mockup to show the concept."

        Comment


        • #5
          My endmills always get dull on the side edges too!

          But... your idea is a good one if one only uses the endmill for maybe a 0.100 depth cut and then cuts that eitire amount off when sharpening. I know many hobbyist that do just that - but they mostly use a surface grinder and a fixture that can be bought to hold it very economically.
          Last edited by Mike Burdick; 05-11-2008, 01:20 PM.

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          • #6
            Hi Mike, for whatever reason, I don't seem to be doing much side milling to dull the sides. The ends and corners, though, that's another story!

            The fixture shown in the pic is in fact designed to be used in a mag chuck on a surface grinder. I have the fixture; now if I could just find a cheap bench-top surface grinder to go with it. Talk about getting the cart before a horse!
            Milton

            "Accuracy is the sum total of your compensating mistakes."

            "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

            Comment


            • #7
              I posted something similar about three years ago,but used a Dremel clamped in an adjustable fixture for angle and the fixture clamped to the quill.

              The endmill was clamped upright in a simple jig in the vice and the jig was made so that it inclined the endmill about a degree if memory serves me,this was so the end was ground concave.

              It was in the first tips book,so it's a while ago.

              Allan

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              • #8
                Should... here's a site I found awhile ago showing it being done.
                http://pico-systems.com/sharpen.html

                The only concern would be the grinding dust on the ways but some rags would minimize that.
                Wow... where did the time go. I could of swore I was only out there for an hour.

                Comment


                • #9
                  Dickey, a couple of things - hey power to you for trying, but you asked .

                  That that relief angle that you are getting by tilting the head also needs to slant in toward the centre a degree or two. Picture the end mill in a collet; the outside of the mill is slightly lower than the inside to prevent rubbing. you may have that angle built into your set up, i can't tell.

                  I agree with Mike, unless you are plunging, going straight down, it is the sides you are dulling not the end. Because the corners are weakest and the poorest at dissipating heat, the wear shows up there quicker....but basically you're wearing sides by how much you DOC is. if you're taking off .200 DOC, you'd have to grand back 200 thou of cutter - kind of grinding away the dull section rather than sharpening it.

                  you've thought about how to use the diamond with ferrous which is good, but I'm not sure what advantage in provides, seems like at those speeds the removal rate would be very slow??
                  in Toronto Ontario - where are you?

                  Comment


                  • #10
                    I have been sharpening my end mills this way for 3 yrs, down to 3/16, 4 flute. I usually use AO wheels. To minimize dust I made a fixture to hold a shop vac nozzle close to the wheel and cover the table with plastic. For those who aren't familiar with this 5C fixture all three angles needed are built into the base.

                    see this link, half way down on the left.

                    http://www.use-enco.com/CGI/INPDFF?P...MITEM=287-6840

                    Comment


                    • #11
                      [QUOTE=DICKEYBIRD]I was setting up to drill the 5C fixture mounting plate for the endmill grinding device I'm building in another thread and I dope slapped myself and said: "Why dont'cha just mount a diamond wheel on an arbor in the mill and use the mill table to precisely move the endmill?"
                      Well for starters that looks like a high speed end mill and you don't grind steel with diamond. The proper wheel would be Norton 38A. BUT with a vitrified wheel on a vertical spindle and no guard you would right in the path of fragments if a wheel explodes. And they do from time to time.

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                      • #12
                        It should work but a couple down sides are fairly slow wheel movement across the tool lighter cuts will help prevent burning the seconds a bit more of a problem in that you have to be really aggresive about wiping down any surface that gets grit on it get covers for the ways and don't retract the quill until its wiped clean. We used a bridgeport mill to grind high speed punchs the grit problem was really hard on it most because of lack of attention

                        Comment


                        • #13
                          Originally posted by DICKEYBIRD
                          You're right Paul, that is a coarse wheel; I just stuck it in to show the idea.

                          Good point about the wedging effect. Didn't think of that. So in the pic, the tool is leaning to the right 5 degrees and I was thinking the wheel should spin in reverse, counter-clockwise. Is that correct?
                          I would think that would be the correct way. But I was thinking the exact opposite after looking at your picture: left tilt and CW rotation as viewed from above.
                          Paul A.
                          SE Texas

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

                          Comment


                          • #14
                            Originally posted by dewat
                            I have been sharpening my end mills this way for 3 yrs, down to 3/16, 4 flute. I usually use AO wheels. To minimize dust I made a fixture to hold a shop vac nozzle close to the wheel and cover the table with plastic. For those who aren't familiar with this 5C fixture all three angles needed are built into the base.

                            see this link, half way down on the left.

                            http://www.use-enco.com/CGI/INPDFF?P...MITEM=287-6840

                            I have seen these advertised before and wondered how good they were. What means are used to hold them to the table? Hand held? Clamps? But how would you clamp it in the 30 degree position? Or magnetic? Or what?
                            Paul A.
                            SE Texas

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

                            Comment


                            • #15
                              Originally posted by Paul Alciatore
                              I have seen these advertised before and wondered how good they were. What means are used to hold them to the table? Hand held? Clamps? But how would you clamp it in the 30 degree position? Or magnetic? Or what?
                              They are for use on a surface grinder with a magnetic chuck. I must point out here that a Bridgeport is not a grinding machine. Think SAFETY

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