Re: [CAD_CAM_EDM_DRO] master precision levels

mayfieldtm wrote:

> --- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> > Well, this may be sufficient for a wood router. it certainly is no
> > substitute for a master precision level, which will easily detect
> > the thickness of a single hair over a lever arm of a foot or more.
>
> Jon:
>
> I have never actually seen one of the master precision levels.
> I have noticed them mentioned on this list quite often.
> Do they use a bubble type indicator or what?

Yes. I have an 8" Soviet-made one, which I think is probably a
copy of the Starrett model. It has a hand-scraped base with a
very shallow Vee recess, so it can be set on flat or cylindrical
surfaces. The tube is about 5" long, with a very long bubble
in it. Each division is roughly .00075" / foot. No typo there,
roughly 3/4 of a thousandth of an inch per mark. These marks
are about 1/8" apart, so they are very easy to read. If you set a
hair under on end, it will move the bubble about 3 divisions!

You can easily read the curvature on the top of an older Bridgeport
table due to gravity-induced sag. You can easily see the twisting
of even large lathe beds by just leaning on them. And, you can
drive yourself a little batty trying to adjust screws on the feet of
a lathe, then popping back up to read the level, then back down to
turn the screw one more 64th of a turn, etc. But, you can get that
lathe bed SO straight and true it is amazing.

I got mine for about $69 on sale. Enco, KBC, J&L and other
machine tool suppliers have a pretty steady supply of these at similar
discount prices. I can't say whether they are as good as mine or
not.

Jon