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Rotary burr v. mounted point

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  • Rotary burr v. mounted point

    The use of a rotary burr compared to a mounted point...

    Is there a "when" as to when one or the other should be used?

    Brand names you have had good success with?


    Working nearly entirely with mild steel, electric die grinder (IIRC, 25 000 rpm, single speed). Most of the time used for enlarging holes, grinding to gain clearances when right angle grinder is either too large, awkward or a bit of over-kill.

    Thanks, Russ

  • #2
    Russ, EVERYONE knows that rotary burrs are for excavating TEETH!
    Seriously, they should probably be limited to quite soft materials, say aluminum and softer.
    Duffy, Gatineau, Quebec

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    • #3


      You mean these?
      Use carbide ones for steel and life is grand.
      Until you have to dig the steel slivers out of EVERYWHERE!

      --Doozer
      DZER

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      • #4
        I hate mounted points. Seems like they always take forever to cut and they don't last long. The guys here suggested I try out some solid carbide rotary burs and now that's all I use.

        Check out Enco - they regularly have Atrax solid carbide burs on sale. They aren't cheap, but they take a beating and stay sharp for a long time. I really abused a couple of mine grinding out some old nasty cast iron and they're still super sharp. Despite the abuse (including regularly jamming the thing in a hole), none of the little teeth chipped AND they're still sharp enough to slit skin!
        Last edited by Fasttrack; 05-24-2013, 01:12 PM.

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        • #5
          I would love to see a "How it's Made" episode on how these things are produced.
          Think they use a sharp diamond wheel to make all those slits?

          --Doozer
          DZER

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          • #6
            Carbide burrs work great but with the aforementioned drawback of slivers. I even use them in my CNC mill to machine very smooth edges.
            Free software for calculating bolt circles and similar: Click Here

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            • #7
              Those burrs I use when in need of material removal with a small air operated pencil/die grinder at 75000 rpm. The carbide versions last a long time, but the mess they make is a hell to clean, especially when your hands and lap is full of the slivers.

              Mounted points (I assume this to mean the small grinding stones) I use when I need to have a good surface or remove small amounts or have to shape the thing first to fit in to a tight spot. They come in several hardness ratings and you really need the proper ones for the material, otherwise they eat up too fast (too soft) or will glaze (too hard). And I mainly have two diferent ones, a coarse for general purpose use and an extra fine for finishing.
              Amount of experience is in direct proportion to the value of broken equipment.

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              • #8
                I find the burrs are AWESOME for material removal. The slivers are mainly generated when you chew hardened steel like welds. At least, the nastyest ones that will puncture flesh. Do it outside with a leather jacket or similar on where the slivers won't embed

                The mounted points are sooooo slow its not even funny, but they basicly never skitter outta control like the burrs. Produce a much better surface finish too, and much easier to control in general. Also good for grinding chipbrakers and such into HSS.

                Also, Learned the hard way a few times, do NOT use a burr on the inside of a hole or other closed feature. Eventualy it will skitter around the ID of the hole and your arm will 'bend' and snap it in half. Mounted points seem OK in holes, but slow. (And who cares if you snap a $0.50 point?)
                Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                • #9
                  I use the carbide burrs and some diamond burrs, along with rotary rasps and stone points..
                  With the 1/4" burrs you have to make sure to have a firm grip on the die grinder so you are actually cutting VS rubbing and chipping away at the item being cut.
                  The rotary burrs are for wood I think and the diamond burrs are more like a stone point IMO. They grind VS cut.
                  And there are some tiny dentist burrs in the mix. JR







                  My old yahoo group. Bridgeport Mill Group

                  https://groups.yahoo.com/neo/groups/...port_mill/info

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                  • #10
                    I use the mounted stones to sharpen my lawn mower blades without even taking them off the tractor.

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                    • #11
                      Thanks for all replies...based on some of the feedback, there are others who have found the mounted points less than quick acting, I was at the point of wondering if I was just using them wrong as they seemed sooo slow.

                      Doozer: yeh, those are them...to my knowledge I have never used carbide ones so that will be the first task.

                      JRouche: agreed regarding actually cutting v. rubbing/chipping...part of my wondering if anything was really happening...

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                      • #12
                        I find a "router speed control" is essential for a lot of grinding with carbide, burrs, stones, flaps, or whatever. That is especially true if you must insert the carbide into a hole, where it tends to catch. When it does, oh boy - it wants to bounce around in the hole - it's a bad experience. I've found slowing things down allows me to maintain much more control.

                        The wider pattern/fewer flutes carbide is better for aluminum. The fine diamond pattern quickly loads up with aluminum. You can use a cutting wax to keep them from getting loaded up and improve material removal a bit.

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                        • #13
                          If you want to remove aluminum material, your best bet is a diamond tool, as the aluminum doesn't adhere to it.
                          Amount of experience is in direct proportion to the value of broken equipment.

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                          • #14
                            I find the diamond tools work great on plastics too. Sure they melt the plastics badly, but they melt through nicely and the plastic can't stick to the closed structure of a diamond burr, you can just peel it off once it cools. (most of it will end up 'shot' off the burr as plastic strings with molten goops on the end)

                            What are those funky tungsten coated ones good for? (Far left of http://img.photobucket.com/albums/v3...SM/diaburr.jpg )

                            Also note that the carbon steel burrs (Rasps?) http://img.photobucket.com/albums/v3...otaryrasps.jpg are only good for wood/plastic and other soft materials, steel will dull them quick.

                            I suspect the 'HSS' burrs don't last very long in steel either. Really worth it to get a good carbide burr.
                            Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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                            • #15
                              Those "funkey tungsten carbide burrs" are Kutzall brand and are super for carving hardwood. In fact they work on pitchy woods too; you just burn them clean with a propane torch. They even make one for an angle grinder. It gives me the willies just THINKING about touching a body part!
                              Duffy, Gatineau, Quebec

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