Yeah there ARE those things that get ya...

I do a LOT of 1/8 scale model work (some of you know I build steam
locomotives).

In the smaller locomotives there are a bunch of 5-40 bolts... 5-40 shaft
size/clearence is 1/8 inch, which is why it's used a lot, scales out to 1
inch.... UMMMM, NEVER, EVER, EVER... get your 4-40 and 5-40 hardware
mixed....

4-40 goes in a 5-40 threaded hole or bolt just fine... till you try and
tighten it...:-)

--.- Dave


"Wes" wrote in message
...
Today, one of our operators mentioned he was missing a special fastener.
I asked him if
there was another one I could measure. Sure, he removed it using a 8mm
hex key, I scaled
it and it looked like a 12mm long fastener with 6mm of it turned down to
6mm to keep a
sliding detail captive. No problemo!

Carbide has no problems with SHCS's but the head of the 12mm SHCS wasn't
all that
cylindrical and didn't fit any of my collets. So I lightly held it by the
threads, turned
head down to a diameter that fit a 9/16 collet and proceeded to make my
fastener.

Didn't fit. Okay, must have mushed the leading edge of the threads. So I
grind on a
lead. Still doesn't fit. Maybe I distorted things a bit, I used a lathe
to turn it down,
maybe tool pressure the bent the leading edge of the thread over. Ran a
thread file
across it, screwed it into a 12mm nut and it fits. Still doesn't fit the
machine.

So I start to get a clue, go back to my tool box, grab a 5/16 hex key and
notice that that
fits a 12 mm shcs fine. I proceeded to learn that a 1/2-13 screw will
screw into a 12 mm
nut just fine but a 12mm screw will not screw into a 1/2-13 nut. Argh!

It was Monday.

Wes