"John" wrote in message
...

As you say to pointing the rest into the hole and laying the tool on it
length wise hence having a large surface area of contact would definitely
increase stability

Something else I just remembered which is probably a big factor is the
height of the rest to centreline of work piece. I was looking into this
the other week, and found that the lowest height of standard tool rest is
(using metric here) 5mm below centre, with the tool being 7mm thick ( One
reason I have been looking at an upgrade to the lathe. But if I make some
rests I can drop that height


Don't jump too fast. Remember, the piece is rotating, and the edge in
contact wants to twist the handle, not tip. Not a lot of gain in the box
toolrests except in bottoming unless you can extend them inside the turning
and up close to the sides.

Percentage play lies in limiting the amount of metal in contact while
scraping by using a narrow bit like Darrel or the other makers of hollowing
tools, or increasing the amount of metal in contact when cutting, thereby
stabilizing on the place you've been to get where you want to go. It's the
principle behind "shear scraping," which is cutting without benefit of a
guiding bevel. If you use the side of your cutter or buy one of those
depth-limiting kinds like the Munro, you're following precept two.

Other thing you may have noticed about the commercial tools is that they get
you handle swing by curving the bit holder, yet keep the bit in line with
the main handle to minimize leverage and twist.

One principle I learned from the first book I ever read on turning (old
bodger name of Frank Pain) was that you can't get a catch if your cut is
above the wood. Inside, that means below the center, outside, above.
Figure your toolrest height from those principles, and things will go a bit
easier.