I like it slow.

I'm turning bowls and plates, and I start at 450, and final cut at 950 rpm.
That's it. I do get a smoother cut at the higher speed, so I shift to it
after the piece is round and all the corners are gone.

I've done less spindle turning, but it has been very satisfactory at the low
end of the range.

I figure the less speed, the less momentum, the smaller the bruise when it
hits me.

I do speed things up to 1500 rpm when I polish the wax. I had a 12"
laminated plate (old butcher block counter) delaminate on me at that speed.
The knot on my arm is still there after two weeks.

It's not the bite you are taking that causes the problem, it's the bit that
the chisel takes when it develops a mind of its own.

I don't like to do white knuckle turning. If I'm putting finger prints into
the tool handle, I stop and do a dry run to see where the tool edge is. If
I get tense, I catch.

It's a wonderful sport.

Walt C






"charlie b" wrote in message
...
The Turning Dilema - RPMs vs Risk (semi-long)

I come to turning from The World of Norm (other heroes - Krenov, Maloof
and Nakashima). I can adequately use handtools - chisels, dovetail
saws, hand planes, cabinet scrapers, some carving gouges, and can set up
and safely use a joiner, planer, table saw, shaper, SCMS, router - in or
out of a table, drill press, drum sander, OSS. Mortising machine etc. .
I've got feather boards, hold downs, blade guards and push sticks - and
use them. I can put a good edge on just about anything flat backed with
a flat bevel - using a Tormek, diamond plates or japanese water stones -
with or without a jig. And I can read grain adequately - on flat stock.

In The World of Norm, I can mechanically limit the degrees of freedom of
movement of both the tool and the stock. With turning, at least the
center/ spindle turning I've been playing with (for me, if it's fun it's
playing), it's the very dynamic brain/ eye / hand coordination that
concerns me. Initiating a "cut" properly and completing it properly is
requiring far more concentration, coordination and, frankly, stress than
it probably should. And RPMs seems to be one of the major causes of my
low to moderate anxiety.

In The World of Norm, the RPMs of the thing biting off pieces of wood is
typically fixed - the more teeth chewing, the smaller each bite is. The
slower you feed the stock to the teeth the smaller each bite is. It's
Biting Off More Than You Can Chew which raises all the hell - and
launches things - at what seems to be at least Mach 3.

In The World of Turning, you've got but a single "tooth" - the chisel,
gouge or scraper, tool angle, feed rate and RPMs determine the "bite"
size. AND, in The World of Turning, unlike in The World of Norm, the
"tooth" can follow the grain of the wood - and if it does all hell can
break loose.

And that leads to my dilema. At 500 RPMS, things happen 1/3rd slower
than at 1200 RPMs - eight "bites" per second vs 20 "bites" per second.
I "know" that my reaction time is greater than a half a second so when a
catch happens, it really doesn't make much difference whether it happens
in 1/10th of a second or 5/100ths of a second - it's happened before I
can possibly react.

Now the Mr. Spock part of my brain says "More bites per second, the
smaller each bite, and, logically, that's safer.". But my white
knuckles, clenched teeth - and sometimes "cheeks", are telling me -
"SCREW LOGIC - SLOW IT DOWN!".

So my questions a
1. Recomended roughing to round with a 1/2" or 3/4"
roughing gouge RPMS, given the following:
- starting with up to 1 1/2" square stock
- 10 to 14 inches between centers and stock
"approximately" centered
2. Recomended RPMS for spindle turning a 1 inch
cylinder 10 - 14 inches long.
3. When you're turning parts down to pretty small
diameters, do you want to work at higher RPMS
or lower?
4. Is "best RPMs" a function of the type of wood?
I know that pine crushes rather than cuts when
using bench chisels while maple, cherry, walnut
and, my favorite, mahogany cut nice and clean.

So much to learn, so many mistakes to try and avoid.

(Turned some year old prunings from a plumb tree.
Nice stuff - and FREE! Fun, this turning thing)

charlie b
aka The Rotationiste in training