On 11 May 2006 17:17:56 -0700, wrote:

You guys all had some very good info...

Here's a link to some photos I took earlier:
http://pg.photos.yahoo.com/ph/cj1210...548scd&.src=ph

Right now trying to get the thread chasing dial working is not my
biggest concern. I've got to get an accurate TPI first. For some reason
though I think this may be all intertwined...

As you can see from the photos I've strictly kept the setting
(according to the charts and gears) to 16tpi. The leadscrew is exactly
16tpi (not anything metric as you can see from the picture). When I
turn the chuck over one rotation by hand I don't get a complete
rotation in the leadscrew.

This obviously points to some kind of gear miscalculation on the
manufacturer's part... (at least that's the only explanation I can
think of at the moment).

Now, as far as the thread chasing dial, I've tried pulling it away from
the headstock while cutting in order to take all of the play out. This
doesn't do anything. I've also tried giving it resistance with the
carriage wheel.

Maybe the thread chasing dial can't work properly if the gears are
messed up. For example maybe when it's set to 16tpi and it's really
cutting close to 17tpi this will then proceed to not let the half nut
engage at the proper time, which will defeat the whole purpose of the
thread chasing dial.

There is about .007" play in the leadscrew itself which I can probably
fix with a thin washer. There is about .014" play in the half nut unit.
This I'll have to pull apart to see if I can tighten it up. This could
definitly be part of my problem with not getting the same cut to line
up and is just not right, but something tells me there's more to it.
Like I said up above I've tried keeping pressure on the carriage (away
from the headstock) and it hasn't done any good...

Any other ideas!?

The chart in photo 11 shows the gear box driven from the 127 tooth
gear which is being used as an idler gear; but, in photos 6, 7, 8 and
9, the gear box appears to be driven by the 120 tooth gear, which only
used for metric threads.
Gerry :-)}
London, Canada