Re: [CAD_CAM_EDM_DRO] Re: RF-45 Retrofit

Terry May wrote:

> Carlos,
> You're right, of course, there is a small flat area, my best
> caliper is a mitutoyo also and I think the flat is about what yours
> is. I don't know how much error that would translate to on a 15mm
> bore?? I still think the ball screws I have are too large for the
> bearings by a few thousanths. I'm going for the fit Peter mentioned
> in his post, a very light press fit on the screw and a slip fit in
> the bore of the bearing block. I think that will give the best result
> when trying to minimize end play on the ball screw.
>
> Terry
>
> --- In CAD_CAM_EDM_DRO@egroups.com, "Carlos Guillermo" <carlos@v...>
> wrote:
> > Terry -
> >
> > Are you using calipers to measure that ID? On a diameter that
> size, the
> > calipers will show a smaller-than-actual ID if there are any flats
> on the
> > faces of the measuring tips. There is almost always some kind of
> flat,
> > unless they are sharpened like a knife. My Mitutoyos have
> about .020" flats.
> > I don't know how significant the error would be, but I don't expect
> accurate
> > measurements with calipers on small ID's.
> >
> > Carlos

For precision bearings Koyo specifies an interference fit of 2 um. ( shaft to inner ring). How one measures preload is still has me
in the dark. I guess one does something reasonable and hopes. (end play??).
I've been know to do things like heat the bearing in oil to 200 F. (carefully now..... exceeding 300 even locally will screw up the
temper).
and cool the shaft in the freezer. They slip together nicely....don't plan on getting them apart without a press. ;-)

dave

>
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