I hadn't noticed that you've got more potential machining capabilities than
just your new Proxxon.
Congrats.. the small machines offer a multitude of possibilities, as Ed
mentioned earlier.

As far as needing a lot od specialized measurement tools goes.. well maybe.
Of course it's good to know how to measure parts and dimensions accurately,
a lot can be accomplished with a couple of calipers.
Also, understanding basic principles of how to attain accurate readings are
of significant importance.. it will undoubtedly be very helpful for various
other measuring purposes.

As long as one's not required to make parts to aerospace specs, there will
always be certain limitations of measuring tools and machines.

A caliper isn't the ultimate measuring tool for measuring the minor diameter
between threads, which is easily seen when using one on coarse threads, the
caliper is no longer reading in a straight line due to the thread pitch.

The percentage of error is quite small when measuring the minor diameter of
fine pitched threads on a part with a caliper.. if the user has an existing
example of the threaded part they want to duplicate, then measuring becomes
a matter of comparison of measurements, not to an exact size specification.

I realize that some folks know trig formulas better than I know my own phone
number some days, so math calculations often cloud the issue of making a
measurement, for me. For certain type of measurements, I know I'll need to
do the math, chart comparisons etc.

Otherwise, wires are wires, and if one would care to do the comparisons and
choose wire the same size for a particular thread size, a common micrometer
or caliper can yield the same results.
The benefit of a common micrometer in this instance is that the anvil faces
are wide enough to span several threads.. although a claiper will yield the
same measurement if the jaw faces are placed squarely across, or diagonally
across the wires.

On short threaded sections such as 4 turns of a fine thread on an optical
filter ring, there won't be much room for the measurement tool to make a
measurement.
Threading charts show how far the cutting tool is advanced into the properly
sized workpiece, to achieve the proper cutting depth for the minor diameter.
These standard recommended cutting depths for a number of popular threads
are etched/engraved into the back side of a "fishtail" thread gage (~$10),
which is a very inexpensive tool for setting up thread cutting tools.

In case it hasn't already been mentioned, Machinery's Handbook contains more
information on metalworking standards and details, than most people are
capable of learning.
There are abbreviated (and not so overwhelming) versions and similar
spin-off books such as the Shop Reference For Students And Apprentices.

So, if one has an example of a known good threaded part, then measurements
can be considered as a comparative process.
Eventually most HSMs encounter threads which are unfamiliar to them, and may
not appear to match any commonly available published standards.
Microphone stand connectors, optics, military/aircraft hardware standards
may all have minor differences for no apparent reasons.

As long as the machine user has an existing part (not just low tolerance
specs listed on a page), almost any matching part can be made depending of
course, upon experience and the required number of tricks up one's sleeve.
I'll not likely ever be an expert at cutting threads, so I usually always
have a "known good" mating part sitting within reach when I'm threading on a
lathe.. and carefully sneaking up on the final cuts works very well for me.

Chucking and threading thin hollow parts can require some additional methods
that don't usually apply to solid stock workpieces.. but there are plenty of
methods to minimalize problems.

Lastly.. threading dies may seem like a logical shortcut/substitute for the
learning process of cutting threads on a lathe, but in general, they aren't.

And then there's that gratification thing, again.

--
WB
..........


"Bob S" wrote in message
...

O.K. My Unimat SL-1000 is from the mid to late 1960s as well.

It is almost certainly the same machine. I actually has Unimat-SL on
the motor box.

I actually have more than one of them at this point. Last year I got a
box of Unimat spare parts flying in formation at a yard sale. It was
stored in a basement, so there is a certain amount of rust. The base
casting, ways, and lead screw on the base machine are badly corroded.
However, there were spare way rods and lead screw included that are
not bad. I would need to make a base. The pile also had a spare slide,
the milling table, a circular saw and jig saw, and a few other
gadgets.

Yes, getting thread wires and/or a thread micrometer would be good.
Very few of the threads will be as small as 50mm though. It sounds
like the thing to do would be to get a metric micrometer set going up
to at least 100mm, plus some wires.

I guess that there is a good reason why almost none of the step
adapter rings sold these days have knurled edges, despite the
potential convenience advantages. I guess that I will emulate the
professionals and not knurl thin rings, at least until I get some
experience and a few projects done.

Thank you again

Bob