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30202 bearing- suitable for home made spindle?

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  • #16
    Moore jig borers use ball bearings with about 4x the preload of a Bridgeport.
    I just think the engineering has been figured out with ball bearings and
    high speed stiff spindles.

    -Doozer
    DZER

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    • #17
      Lots of good points, thanks everyone. I think for what I'd be doing, and if I had to be bent on making one, I'll be searching out angular contacts- maybe something in a low profile so I can keep the size down. But I'll be looking again to buy a ready-made powered spindle- it's going to cost money anyway, and I'd be able to use it almost right away. Bonus
      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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      • #18
        One of the chinese spindles is a good option. Another if you can find one used is the NSK spindle system. Small motors, 1" diameter and a whole lot of options like different tool heads, gear reducers, right angle heads, etc. The one I have does 40krpm and I used it with .014" end mills with an adapter that mounted the motor to the quill on my mill.

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        • #19
          Honesty, I wouldn't even spend the money for angular contact bearings.
          Just get some ball bearings and preload them axially, and see what results you get.
          Probably work and last a long time.
          Can always buy better bearings later if what you have does not last long.

          -Doozer
          DZER

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          • #20
            Well- looking at routers, there's no particularly high spec for the bearings- not that I'm aware of anyway. I could pull a bearing out of my drawer to use and it would probably be fine.

            I've been thinking about the heat that's generated by a rolling element bearing- and how you really do want to keep the temperatures there near ambient. A good reason to run a more efficient bearing.

            I can imagine that there would be an optimal oil one could use, one that would play very nicely with a rubber seal and generate little heat even at high speeds.
            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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            • #21
              10k rpm is not high speed with most bearing sizes 50k rpm is.

              As speed goes up, the amount of oil goes down. I think I have mentioned here the client that had a 50kRPM turbine application, and had a flooded bearing pumped oil system. First time they ran it at 50k RPM, the oil got it hot, and the bearings failed in a spectacular fashion.

              I saw them, the balls were little black rough cubes,the races were blackened and soft. They should have used an oil mist or the like. just too much oil. Not large diameter bearings,

              At 10k RPM, oil or grease at most sizes. You would not want rubber seals with oil..... you likely meant the shaft, but I am not sure there either.
              CNC machines only go through the motions

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              • #22
                Somewhat OT but I wonder who makes the brgs in the GE jet engines, and how much they cost, and how do they lube them. And, most importantly, how do they inspect them for MTBF?
                25 miles north of Buffalo NY, USA

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                • #23
                  Interesting concept of using a TRB for high speed. It would be much stiffer if you preload it properly but as others have said, it will run hotter. You will only know by testing, as it's fairly small it might not be too bad. Try to get a Koyo one, they are the best at making efficient TRBs but might only make those for specific automotive products, hard to tell what you get if you order a catalog one.

                  If you're building one try it with a small preload first and watch the temperature, only tighten it further if it doesn't get too hot.

                  All the best spindles use ACBBs as they run cooler and it's cheaper to make an accurate ball bearing than a taper roller one. Precision bearings are already expensive enough. If you gang up something like four ACBBs you are also creating a stiffer spindle as it's not bending around a single point anymore.

                  If you want to try with regular ball bearings, try to get ones with extra clearance, often marked C3. This will get you a better contact angle in the direction of (but still far from) an angular contact bearing.

                  On the jet engine bearings, I think all the major bearing companies do them. They are often thin section bearings, usually angular contact or cylindrical roller with a machined solid brass cage, sometimes silver plated for better dry running properties. Often the outer ring includes flanges for direct mounting. I wouldn't be surprised if they were tens of thousands each.
                  I don't think they are inspected, they will be replaced regularly and there's probably a condition monitoring system on it watching vibration modes.

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