Todd Rearick wrote:

As part of my "getting to know you better" plan with my Smithy 3-in-1 combo
machine, I was using a dial test indicator to see how accurate the spindle
mount on the lathe is. There seems to be a 0.001" wobble. I've checked the
face of the spindle, the inner tapered part (it's a D1-4 spindle), and
finally I put a dead center in the spindle and checked that. I see the same
1 thou. wobble everywhere. Is this typical? Seems like, even if I mount
between centers, the end near the lathe spindle is going to be slightly
out-of-round.

I don't notice any play in the spindle (I can't move it side-to-side or
up-and-down by pushing against it....and I've verified it isn't moving when
I do this by looking at the dial indicator)....however, ever since I've had
the machine the spindle bearings have made a little rattling noise. I don't
really see how a bad spindle bearing could cause the wobble. It looks to me
like the spindle is simply mounted slightly off center.

So Todd, you're thinking it's impossible for "them" to make a bearing that isn't
perfect? Just because bearings are supposed to be manufactured with miniscule
runouts doesn't mean someone can't have a bad day and make a sloppy one. (Or
maybe a whole bunch of them.)

If you do use a 3-jaw chuck, as another poster has said you'll be lucky to clamp
the stock within a thou of running perfectly anyway, but parts turned on the end
of that stock will be OK as long as you don't unchuck the stock before they are
completed.

If you have to unchuck and rechuck, it can help a bit are to mark the stock and
the chuck so you can replace the stock in the same angular relationship to the
chuck.

Also, find the "master" pinion on your chuck, the one which when tightened,
providuces the least runout of a round test bar close to the size of the part
you're chucking, and always use that same pinion for the final scrunching down
of the chuck.



...or maybe I'm just being too picky?

Methinks you just may be, for more parts than not.


Todd Rearick

Jeff (Who's had to learn how to get the best he can out of what he's got.)
--

Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can smile when things are going wrong, you've thought of someone to
blame it on."