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Plain bearing machine spindles - maximum speed?

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  • #31
    Originally posted by greystone View Post
    Pressurised bearings are NOT plain bearings.
    .
    Hydrostatic and hydrodynamic (hydrodynamic is more correct description of what my machines have) are both either plain bearings or both not, depending on the source.

    Jerry, the slow part is easy (DC motors on both).....but i'll also run a 1/8 endmill in it, and commonly say a 1/4.....so knowing the machine what would you feel comfortable setting it up for? I'm thinking the same 1400-1500?
    Last edited by Mcgyver; 03-28-2016, 09:09 PM.
    in Toronto Ontario - where are you?

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    • #32
      Well, I do not have one (you asked, and I forgot to reply), so I may not be the best one to inquire of. I have a Lewis horizontal and a Benchmaster (with both setups). Both of them have roller bearings, although the vertical head for the Lewis is plain bearing.

      My thought concerning the slow speed was that possibly the optimum for slow and heavier load might be different, but subsequently I realized that it's nearly the same, as back gear on the lathe would typically be with larger (and presumably heavier) work. Similar enough to running a 4" cutter at 50 SFM with the mill.

      However, 200 SFM with the 1/8 endmill (slow for aluminum) would be something like 6400 rpm, so perhaps not too practical. The 1600 rpm for mild steel (@100 SFM) and a 1/4 endmill could be within reason. Slower, sure. I don't know how the spindle diameter and bearing length compare on the two.
      CNC machines only go through the motions.

      Ideas expressed may be mine, or from anyone else in the universe.
      Not responsible for clerical errors. Or those made by lay people either.
      Number formats and units may be chosen at random depending on what day it is.
      I reserve the right to use a number system with any integer base without prior notice.
      Generalizations are understood to be "often" true, but not true in every case.

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      • #33
        my mistake, I thought you had a little hardinge horizontal as well. using the eyeball caliper its probably not too different dia between it and the holbrock, and was figuring the overall approach was similar. insofar as i can tell, Hardinge used a lathe headstock - even the the top of the mill is scraped into a lathe bed shape to take the 'headstock".... so i'll set it up for around 1500 max
        in Toronto Ontario - where are you?

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        • #34
          Oh, THAT Hardinge..... I was thinking of the later MD3 or MD4 ones..... which could be had in either plain or ball bearing.

          Yes, that one pretty much is a lathe headstock, so should do the same speeds.
          CNC machines only go through the motions.

          Ideas expressed may be mine, or from anyone else in the universe.
          Not responsible for clerical errors. Or those made by lay people either.
          Number formats and units may be chosen at random depending on what day it is.
          I reserve the right to use a number system with any integer base without prior notice.
          Generalizations are understood to be "often" true, but not true in every case.

          Comment

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