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  • Any other ideas for keeping a diamond wheel (not lapidary disk) wet enough while grinding? How wet do they have to be?


    • Originally posted by challenger View Post
      Any other ideas for keeping a diamond wheel (not lapidary disk) wet enough while grinding? How wet do they have to be?
      Not totally wet. Just damp should to it to keep down the heat. A wet sponge riding on the wheel as in a previous post would probably work OK. However, a real water bath is probably the ideal.
      I use an aquarium pump with a tray underneath to catch the water.
      VitูŽria, Brazil


      • Stefan has a great video on building a machine using the lapidary discs:

        "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


        • Originally posted by ATW View Post
          I wanted some physical stops on the rotary table...
          The one possible drawback I can see, is what happens when you want the stop at/near one of the T-slots - oh well that will be a project for another day, maybe need to make some wider stops for those occasions.
          Looks great Andy. To fix your last issue and the potential marks to the top of the table, could you make the stops as a flexture that expands and grips the slot? That way it wouldn't mar the top and you'd also keep the full top clear. If you made them wide enough to span the T slot, you'd be able to use them there too. I was thinking - but sure it could be bettered by someone with more than half a clue (my situation) - that you could make the protrusion to fit the slot, slit it, pre-spread it with a wedge and then drill and tap it. A set screw should then be able to spread the slit and cause it to wedge in the rotab's peripheral slot. The set screw being at right angles to the Z axis if that helps clarify things.


          • Originally posted by Cenedd View Post
            could you make the stops as a flexture that expands and grips the slot?
            Thats a good idea, I'll file that one away should I need to re-spin them.


            • I like to use a 1/16" or 1/8" pipe tap and plug for that type of application, as they are tapered and expand more the further you screw them in. Then you can just make the part to a close slip fit, drill and tap, then make the slit.
              Kansas City area


              • How wet do they have to be?
                It's mainly to keep the heat DOWN, and to clear away the grindings.
                Basalt grinding

                I flood the diamond cutter as you can see. That seems to be enough.
                But then I have to drain all the dust out of the tank, which requires a bit of flow. The drain is not visible in this photo.
                The basalt comes from the local railway yards: ballast off the side of a shunting line.
                Clear surrounds so I can see what is happening.



                • RC, not to hijack this thread but what is it you are making if you don't mind me asking? Thanks, Jim


                  • Hi Jim
                    What am I making?
                    Well, drilling ruby balls was to see if I could make my own stylii for touch probes. The answer was yes.
                    Machining basalt was to see if I could. The answer was yes.
                    The shapes were mathematical 'things' just to see if I could. Click image for larger version

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                    These are wood prototypes prior to machining basalt. I doubt they serve any useful purpose, but I am a retired research scientist, I have a (solid) CNC mill, I write my own programs in g-code and I can handle the maths involved. Does that explains things? Maybe not ... ๐Ÿ˜Š

                    I haven't done much with basalt recently as I am making and selling ultra-light high-tech remote inverted canister stoves of my own design for winter mountaineering. That pays better too!



                    • Thanks Roger, just being nosy. The basalt machining looked sort of like a chess piece. Do you make the stoves out of titanium? (Seems to me the purpose is in the execution, useful or not...) Jim


                      • Nice rotab stops idea! I'll have to look at mine to see if the same style would work or if I need to adapt.

                        Thanks Dickey for the link. I'm half way through watching it with the morning coffee.

                        That made me go back a bit and realized that I missed the earlier reference by wbc to the speeds. While he gets away with up around 1800 rpm I think a bit slower might be better. Or at least going with a more variable speed setup. Not sure what sort of option yet. But clearly the final honing and polishing is best done at very low speed like 150 to 200 RPM.

                        And Stefan's magnets in the aluminium disc with drive pins is perfect. I suspect it'll mean the drill only last a couple or three holes even drilling from the back but that's not a big deal to sharpen them.... I can touch them up on the first disc on the machine ! ! ! ! ๐Ÿ˜
                        Chilliwack BC, Canada


                        • Re: The cut knurler, from 3 or 4 pages back in time:

                          Moved on to re-purposing orphaned Phase-II bump knurler into a straddle knurler with some 3/4" scrap square stock.
                          Clamping rod is positioned to allow up to 2-1/4" diameter stock. 1/4-28 threaded. Geometry such that one turn
                          of clamp screw closes wheel space down 0.060". Added a pin to spring bore to prevent deformation, then added
                          a small plate to retain the pin. Ooof. Started down that path because did not have material to make a custom hoop
                          spring that could wrap around arm pivot bolts. Could not put spring at clamp rod and still get 1/8" to 2-1/4" spring action
                          without work to the original QCTP base to increase the arm pivot spacing.

                          Tommy bar an after-the-fact addition...thought it would be easier to crank the knurled knob given I made it so large...
                          so next time, could use smaller knurled knob with tommy bar, or just a nut.

                          Easier than cut knurler to set up for the random knurl; more forgiving/self centering; better for small diameter knurl,
                          at least for a terminal beginner like moi.

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                          • wbc Nice. I like the way you're building all of these directly into the QC tool holder rather than as a shank held in holder. Between the more direct hold and being located closed to the post, it ought to mean it's more rigid.


                            • Hi Jim

                              Do you make the stoves out of titanium?

                              Ah well, that is a long story, spanning 10 years or more. I am a retired research scientist and a bushwalker. But not being young any more, I yearn for a lighter pack. Also I go ski touring, which can be too cold for the simple little upright canister stoves. What all that means is that I want a remote inverted canister stove, but not one of the rather heavy and clumsy commercial ones. It seemed to me that improvements were possible ... and you know where that leads!
                              My manual machining is tolerable, but not good enough imho. So I bought a good CNC machine, good to 0.01 mm easily (ie not Chinese), taught myself how to write g-code, and ...

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                              On the left we have my Version 3 stove. It is a 'vortex' burner, and makes a bit of noise. Complex aerodynamics inside.
                              On the right we have Version 4, with a (fairly) quiet burner. More complex aerodynamics. I have skipped V-1, V0, V1 and V2.

                              The really hot bits are indeed titanium alloy. There is also some SS mesh on the right. Both use aluminium for the non-hot parts. The handle on the right is carbon fibre tubng. The connection to the canister (out of sight on the left) uses acetal, nylon, PET, Lexan, brass, and there are several Viton O-rings here and there. Eclectic.

                              Sales are to fellow light-weight bushwalking enthusiasts around the world. I am getting close to 200 so far. Great fun, and I have paid off the CNC!

                              Last edited by rcaffin; 05-21-2020, 04:16 AM.


                              • Here's my scissor knurler.
                                The Marlco copy by Hemingway Kits in the UK, capacity is 2.5", nice bit of kit...
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