DoN. Nichols wrote:
On 2010-12-06, Searcher7 wrote:

Can I get recommendations of which and how many screw thread
gauges(gages?) one should own to cover the most common threads one is
likely to run into? (Including metric, but I live in the U.S.).


Two -- one metric, and one inch. There are inch ones available
(mine is from Starrett) which have three groups of gauge leaves, and if
that doesn't cover what you need, it will probably be a coarse enough
thread to measure by a steel ruler -- and too coarse to cut on a home
lathe.


There seems to be a lot of overlap between gauges and I just want to
get what I need.


Just get one which covers the maximum number of *reasonable*
threads.

The Starrett No. 472 which covers from 4 TPI to 84 TPI (51
leaves).

You could add the No. 155, which covers from 28 TPI up to 2.25
TPI -- but -- why would you need to measure one that coarse, since you
can't cut it at home anyway.


My Harrison M300 does 2TPI as standard and it has been needed on one
occasion when my neighbour needed to cut an internal twin start square
thread for the nut on his dining room table jack as it had finally wore
out after about 200 years. He couldn't do it as his Myford Super 7
doesn't go that coarse so he came around and did it at my house.

The Starrett No. 156M covers 28 Metric pitches, from 0.25 mm to
2.5 mm.

Perhaps you *could* add a No. 159M for threads from 1.00 mm to
11.5 mm, but you are not likely to need that for any threads which you
can cut on a home lathe or with a reasonable sized tap or die. The 2.5
mm which is the coarsest of the previous one is about 10 TPI which is
coarse enough for most purposes. The 11.5 mm thread pitch would
translate to about 2.2 TPI.

Essentially -- *think* about what you will be capable of working
with. (Check what range your lathe can thread for example. I think
that the No. 472 and the No 156m should do more than you really will
need.

Good Luck,
DoN.