"Toller" wrote in message
...
I cut a 18" crab apple log in half, sketched out an 12" circle on each, and
roughly trimmed it with the chainsaw. Unfortunately it was way too big to
fit on my bandsaw, but it would have bound anyhow.

I screwed a faceplate to the flat surface and ran the tail piece into it.

Well, the lathe shook like crazy, and thunked pretty badly each time a
high spot hit the gouge. (400 rpm, the lowest setting on the machine) I
have roughed out both the outside and the inside and the lathe seems to be
okay; once I got them balanced they spun just fine.
But I wonder if a lathe is designed for that? Without a really big
bandsaw I am not sure what I could have done to make it any better.


Instead of just cutting in half, you could have undercut those end grain
portions which were going to be removed while getting the piece into bowl
shape. By reducing the diferential mass far out on the edge you could
reduce the problem to a minimum. Slowest speed, of course. You can even do
a static balance, mark and remove mass from heavy spots if you cared to.
Take the marked piece off the lathe and use a big carving gouge.

You can also use even a modest bandsaw with tilted table to nibble away
unwanted wood. I've used ~8" thick wood on a saw with 6" clearance by
nibbling round top, bottom, and middle, though only when I was trying to get
the absolute max diameter. Usually the chainsaw's enough.

On a completely different issue, the crapapple has pretty streaks of red
running though it, mixed with brown and white. Is that going to last?

Should. the darker is brown rot, and if sound, will last. Streaks of white
show in pieces fifteen years old that I made.