"DoN. Nichols" wrote in message
...

snip

The problem arises with the Taig also. None of the chucks will hold a 4"
piece. I do the insides with a boring head on the mill and finish on the
Taig.

Hmm ... I would have to go down and set up the chuck with the
extruded jaws to be sure -- but remember that you can bore a recess in
the jaws up to within perhaps 1/4" from the ends of the fingers.

But you could *make* pie jaws from solid aluminum plate at need
to have the extra reach needed.

The Taig swing is 4-1/8" ...

And if the swing of the lathe is the problem, add one or two
riser blocks between the headstock and the bed. Those riser blocks will
stack if you have (or make) two of them.

I considered that. Those who know better than I told me that the rigidity
declines quite significantly. Machining 4" with the existing setup is a
constant struggle with rigidity as it is.

[ ... ]

Hmm ... replace the motor with a DC motor and a proper speed
controller, or a small three-phase motor and a VFD to run the motor at
perhaps 1/4 speed. (about 140 RPM).

Or for the same money just get a bigger lathe. I went through this some time
ago. The torque at the low speed is a big problem with the Taig. Even as it
is I have to lean on the motor some times to stop it stalling. It is what it
is: A little lathe for little things.

snip

Or -- use uncoated carbide inserts to survive the higher speeds.

I tried those. I thought they were horrible. Got much better results with
properly ground HSS.

This is all done on the un-modified Taig:

http://www.flickr.com/photos/2768312...7622965185636/
(well, just the step - much milling there also)
http://www.flickr.com/photos/2768312...7605638700703/
http://www.flickr.com/photos/2768312...7605638700703/
http://www.flickr.com/photos/27683124@N07/4358722420/

There has been a learning curve :-)

http://www.flickr.com/photos/2768312...7605638700703/

In any case, I really have no idea what is a reasonable expectation of a
good finish achievable by a lathe of whatever size. This 1' beast was turned
by a professional. The concentric ridges are apparent. Can one ever get rid
of them? Can one make them look uniform without a power-feed? Should one go
back to facing with sandpaper and just do the edges on a lathe/mill? What is
the meaning of life...

--
Michael Koblic,
Campbell River, BC