No holder. The use of thread wires with your object still in a lathe is
very easy, with a holder only adding to problems. One of the problems
would be the influence the holder would have over the wires. That may
sound trivial, but it's not, and a caution of this very thing accompanies
good wires. The wires must be free to conform to the thread. Even a
little tape on one end can influence a reading, especially on larger wires.

People with your ability with math would have no trouble calculating the
proper measurement over wires when choosing random diameters for measuring,
but folks like me, with only a high school education, one that did not
consist of any advanced mathematics, would have a difficult time calculating
the proper readings. Further, and in this case it likely makes no
difference at all, if you were chasing threads that needed acceptance by
inspection, the readings would most likely be disputed by an inspection
department. Standard thread wires (not the little cheap PeeDee sets, but
the wires sold by such firms as Deltronics) are precision instruments, with
diameters held to millionths, and come with certification. The wires are of
such a quality that they can be used for certification of thread gages.
These wires come with a constant that is added to the maximum and minimum
thread pitch, which one fetches from a source such as Machinery's Handbook.
Measuring threads by this method is very simple and is acceptable by
inspection. It is likely well overkill for the home shop type, but is good
and acceptable practice in any shop.

Back to the use of thread wires. To use them, one sets the mike so it's
opened slightly larger than the intended reading, places two wires on the
top side of the item to be measured, spread a distance slightly narrower
than the diameter of the spindle, then straddles the wires with the spindle.
lightly pressing the wires to keep them from falling. The third wire,
which is held in one's lips, is then slid between the anvil and the part,
splitting the distance between the top wires, so a three point reading can
be taken. When the open distance is fairly close, the wires will stay in
place with no trouble at all once the third wire is installed. One then
tightens the spindle, keeping the face parallel with the top two wires,
rocking the mike for feel, until it is measuring the distance over the
wires. Once learned this way, it's very easy, and fast, and requires
no holder.

One word of caution, and it matters not the source of your wires, be they
the expensive commercial wires such as the Deltronics, P&W, or just the
simple set sold be PeeDee: ALWAYS clean out your chip pan when measuring
threads. It's amazing how a long wire looks like the rest of the chips when
you drop them.

Good luck!

Harold


For practical home shops is there any advantage to using wires instead
if a thread Mic ? The cheap imports look a lot more convienient .
Ken Cutt