Fowler Clinometer accuracy and theodolite, was Re: Mill needs levelers

Ken Garver <dunlapsville@...> writes:

>Subject: Re: Mill needs levelers

> Starret and Fowler sell precision levels for
>this. The 8" Starrett is about $70.00 after your discount (two years
>ago pricing). The 6" is cheaper but it may not span the ways of
>your lathe. Hit Ebay. I got a $2500 Fowler Clinometer, adjustable to
>any angle, accurate to 1 second, for $98 delivered to my door!

Is this the Clino 2000?
I think this is the best one.
Accuracy is rated as 30", or 5" + .07% of readout. This is after "quick
calibration aids" have been used.

Take the 30", this is an angle of .0017 inch/foot. Looks like it is good
enough for the job.

Some of the other Fowler Clinometers have linearities of 3', which is .01
inch/foot, wouldn't be reliable for that sort of work. Still a fine tool,
though.

If you decide to measure angles more precisely, use a theodolite. My Wild
T3A will do better than 1", it reads directly to 0.2", but that is only
really achievable with some averaging of multiple measurements.

I intend to cut some tapers (J33 & M2) using the theodolite. A straight rod
will be indicated on the lathe, and the compound turned so that its travel
is parallel to the lathe axis. A reference mirror will be placed on the
compound, and zeroed to the theodolite, which is sitting on the lathe (HLVH)
bed. The theodolite will then be rotated to the proper angle, which is
1°49'6.2" for J33, and the compound rotated to center the image on the
theodolite reticle.

The theodolite is useful for lots of machine accuracy measurements, this is
why the T3A has an autocollimator built in. It can be use to measure
straightness, orthogonality, level, runout, and so on to arc second
accuracy. Surface plates flatness can be measured to <.00005" with them.
When electronic ones came out my older mechanical ones became available on
the surplus market.

For big mills and routers they are ideal to check out way accuracy.

In the range of precision for which it is intended, the Clinometer will be
much quicker. It will not measure horizontal angles though.


Elliot B.