Final Answer-Follow up questions: Re: Linear bearings

I contacted Thompson and got an engineer today who spoke English
(yesterday's seemed to only speak Russian and we couldn't hold much
of a conversation).

1) They grade their balls by the millionth of an inch into 22
catagories and the balls in a given bearing have to be EXACTLY the
same size. Too small and they don't make contact, too big and they
can score the rod. I probably already screwed this up by re-inerting
the balls I picked up off the floor, but ce la vie! At least the
track involved is one of the upper ones (on each of the two ball
bushings involved) and doesn't bear the majority of the weight.

2) It's OK to be missing a couple of balls even on the load bearing
tracks. One of mine I filled, the other is missing 4 balls, but
since it's not load bearing, he said that was prefferable to buying
replacement balls as they would do more damage than good because of
their microscopic difference in size from the originals.

Just thought it made sense to post this in case anyone else finds
themselves in the same predicament one day.

Jeff

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "washcomp" <jeff@w...> wrote:
> Jan and others:
>
> Thank you, I was able to squeeze them back in without problem.
>
> I'm missing a few balls. I've located a source (McMaster-Carr),
but
> I'd like some advice as to whether the ones I picked out of their
> catalog are appropriate.
>
> Description:
>
> Precision Grade Chrome Steel Balls conform to ASTM A295. Made from
> ANSI Type 52100 steel. Widely used in precision ball bearings,
these
> balls are through hardened for maximum strength. Grade 25 balls
have
> a diameter tolerance of +/1 .0001" and a sphericity of .000025".
>
> Also, there are no lubrication points that I see on the ball
> bushings. Do you recommend I oil them (if so, with what weight) or
> pack them with Moly gear grease?
>
> Thanks for the help,
> Jeff
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, JanRwl@A... wrote:
> > Jeff: Since you are ALREADY panicked, guess it won't much ADD to
> your misery
> > to ask if you can REMOVE the ball-bushing in question â€" take it
> plumb-OFF the
> > shaft. Sometimes, that is just about the ONLY way you can get
> enough "play"
> > (aka "slop") between the ball-return groove and the hardened
> grooved bit of
> > steel the balls roll in. That bit of steel must obviously lift
> away from the
> > round-way JUST enough yo letcha push the balls in.
> >
> > Things may "seem" to work even if you have several balls missing,
> but don't
> > forget, a relatively small % of the total # of balls are actually
> supporting
> > weight/force at any particular time, so if more than one or two
are
> missing, the
> > "stress" on what's left will PROBABLY cause undue wear-rate, if
not
> imminent
> > destruction.
> >
> > I never saw ball-bushings with a HOLE into which one could push-
in
> balls.
> > This Thomson stuff?
> >
> > Lotsa luck! Jan Rowland
> >
> >
> > [Non-text portions of this message have been removed]