I'm just getting back to turning - have been doing it for 30 years on-off
busy in metal most of the time now - but have to do a large handle for
a 2" size wrench of 1/4" steel I made for my Uncle.

I suggest that a 5:1 ratio did it - consider a small pressure is amplified
5X to the smaller diameter or 25x of the cross sections.

It might be worse - have to consider the Math ...
surface pi*D 6" vs 30 same ratio
consider cross section - pi*r^2 3.14 vs 78.5 large ratio.

Sometimes we overlook the forces at work.
Maybe soaking the tenon in the first (or now) with thin CA might fortify
the grain.

Martin

Barry N. Turner wrote:

Yep. You're right, side-grain bowl. But, it wasn't aggressive hollowing
that caused the problem, just a @#$%* catch. Gotta learn how to use that
Ellsworth grind.

Barry


"william_b_noble" wrote in message
news:1123386949.3a18ea4a5d8508ba8b70563ec96ba00f@t eranews...

if I had to guess, barry, the grain is running perpendicular to the ways
rather than parallel to it - mahogony is not strong in cross grain shear -
just don't be so agressive in hollowing - if the grain were running

parallel

to the ways, 2" would have been plenty strong.

just my 2 cents

bill N (been there, done that, sadly, more than once)


"Barry N. Turner" wrote in message
...

I went to the shop to turn a bowl. I had a dry 10" X 10" X 4" Honduras
Mahogany blank that I bought some time ago. I turned the outside shape
with
a 4" foot and a 2" tenon. I power sanded the exterior and reversed the
bowl
to hollow it. After hollowing, I intended to reverse the bowl again and
turn away the tenon, leaving a simple 4" concave foot.

I trued the rim and started to establish the wall thickness, using my

new

Crown PM bowl gouge. All was going well. The bowl was hollowed about
halfway down when I got a king-sized catch and ripped the bowl from the
chuck, leaving the 3/8" X 2" tenon behind in the jaws.

The bowl is intact, except for a deep gouge in the rim, which can be
turned
away. I salvaged the tenon from the chuck jaws and carefully glued it
back
to the bottom of the bowl using medium-viscosity CA glue. I'm going to
leave it clamped overnight and try again.

Considering the ease with which I was able to rip the tenon from the

bowl

made me wonder, is a 2" tenon adequate for turning a 10" diameter bowl?

I

suspect that it may be on the small side. Thoughts?








--
Martin Eastburn
@ home at Lion's Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder

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