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  • #16
    A couple of those were on ebay a while back.
    You might check on that before making the whole thing, might come up again.

    I think they maybe didn't sell, too pricey. The seller might get better sense soon.....

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    • #17
      Your darn tooting right pricey,

      I looked at one that someone makes and sells for 1000.00$ and it looks like its made out of an erector set and plywood, both are good in there place but sheesh... only had one chuck to..

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      • #18
        Samuel:
        So, what you are telling me is you are making giant Bongs? Nudge, Nudge, wink, wink - say no more!

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        • #19
          Frankly, no

          Although, a few years ago... er um...... how the heck would you know about any of that sort of thing! Hmmmm I know someone that makes 60 $ hr making "scientific" (ya right) glass which is a little more well ok alot more than yours truely makes.. thanks for the Idea !

          In Jest, on shakey ground, with two strikes

          Samuel

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          • #20
            What sort of speeds do you need to run at?
            If low, you may consider getting 2 scrapped pipe threading machines and make a bed to mount them on out of structural steel.
            A 2" cap. machine will have a bore of about 2.75" and most have a self centering device on the outboard end of the spindle. They are always equipped with a self centering 3 jaw chuck which on the newer machines (last 30 years) are hand tightened. For holding hot glass I guess you'll have to make some sort of pads for the jaws, I don't know, maybe some sort of high temp. silicone.
            Also they are always reversible so if the speed is right and you have 2 identical machines, you can cobble it together quick.

            The draw backs about this are, the bearings are not precision or designed for high speed. They are usually brass journals, sometimes split and usually no provisions for oiling.
            The base of a threading machine will probably not be parallel with the bore of the spindle, but this can be fixed by milling the base or shimming or both.
            If the speeds are not right, you may have difficulty changing it, most are driven by a large spur gear mounted on the chuck end of the spindle driven by a spur mounted on what looks like a large drill motor, which is mounted to the frame, (vaguely similar to a backgear on a lathe) and you may have trouble finding machines at an affordable price. Plumbers think they are made of gold, even after being abused for 20 years or so.
            Check ebay.
            Hope this helps.

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            • #21
              BTW what is "didimium eye-are"?
              Sorry for being so ignorant

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              • #22
                yf,

                Thanks for the Ideas, never thought of doing it that way, its very helpful to have some alternate perspectives... I am not sure if your kidding or not but I meant to say didimium eye WARE like glasses... I am really looking for something light weight,( I dont need lots of strength and its easyer to find smaller dc motors w/ speed control) I could cast a simple chuck, out of aluminum but I need a little more think-time about making the pattern.. if anyone has any Ideas wink wink.....

                keep makn' chips and I will see ya'll soon

                Samuel

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                • #23
                  You still didn't mention what speeds you need to run at.
                  50 RPM... 1000 RPM...???

                  Wasn't kidding about didimium eye are.
                  Never heard of didimium. Is that something like unobtanium?

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                  • #24
                    sorry bout that, between 6 and 250 rpms

                    something like that.... its some sort of mineral? maybe proprietary name? that is put in the lenses, the are almost clear, and you can work with some really bright stuff....

                    Thanks

                    Samuel

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                    • #25
                      A pipe threader might be good for 250 RPM.
                      You will have to modify it though, the fastest one I've seen was about 80 RPM.
                      One thing is for sure, the bearings can take very heavy loads.
                      For higher speeds you will have to make some arrangement for lubricating the bearings.

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                      • #26
                        yf:
                        I think it is gold over Iconel and then flashed with Titainium and another metal. Gold over Iconel is a near perfect heat mirror (Iconel absorbs the heat an prevents the glass from heat fracturing. The other flash metal provides protection from blue and ultraviolet, the Titainium from the yellow.

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                        • #27
                          Thanks Dave.
                          I wonder where the name "Didimium" came from?
                          Probably some marketing thing.

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                          • #28
                            Hey boys,

                            thanks Thrud, I was wondering what was in those things. this lathe doesn't need to handle barely any load, so far I think that I will make castings, never made them that large but, push the limits eh... hope you all have a good holiday thanks


                            Samuel

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                            • #29
                              I built my first glass lathe in 1949 in graduate school. You'll need no more than 60 rpm, usually much less. The toughest part of the design is keeping the chucks in alignment at all positions, since cold glass won't bend. 2" glass tubing will tolerate perhaps 0.0001" runout, while 1/4" tubing is a lot more flexible. The chuck jaws were actually 4"-long steel rods, parallel to the axis of rotation, covered with asbestos fabric shields. What you'd use now is not clear. Rotational synchronization was done with chain drive. Today I'd use timing belt. For a bed I used 3" x 6" channel and 2 parallel 1.5" drill rod bars for guidance. Drill rod because it is straight and polished. Headstock bearings were brass, as were the sliding journals. Headstocks were welded up from flat plate. And didymium glasses are just that - they contain that rare earth in the melt. They specifically absorb the sodium yellow (D-lines) to give a clear view of the hot glass. I still have mine - they are great for brazing.

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                              • #30
                                jix:
                                Thank you for the correction.

                                I have used the Gold over Iconel for laser mirrors on CO2 lasers and sun filters for telescopes. I know that Titainium is used on eyeglass lenses in addition to the green anti-reflective coat. There are ski goggles out that have a metal ion sputtered onto them and they block blue and ultraviolet. I was making a guess at it, but never thought of the obscure elements as a primary additive in the lens itself.

                                Sorry for leading you astray.

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