thanks for your replies guys,,,
the A frames are from atop a Heinricci hot air engine..

My real problem,, the one i can't get around is this main casting block which is the water jacket and top half of
the displacer cylinder, needs a 2" thread cut underneath and a compatible thread cut on the brass ring photo'd
with it...I would then silver solder the rest of the cylinder onto the brass ring ...I have done all the other parts except
these two, (three counting the A frames)..

.. the problem is its too big to turn on a mini lathe...and i'm usless at thread cutting as well...but i keep doing the lottery so maybe one day i'll be able to get a bigger lathe,, haha,,,

these photo's are old and most parts have already been done or machined close to finishing sizes...with a little help from
David Drillin...(well,, it is a hot air engine!!

)


It looks like a really tricky thread to cut as there is very little room to do it,,length wise...well it looks difficult to me, but i have'nt really got a clue when it comes to thread cutting..
...Mike..