It was time to make another thirty or so favors for Lori's Waves & Navy
Nurses monthly luncheon. I chose to make small ring bowls and turned
them from mahogany offcuts and burned a crude fouled anchor in the
bottoms. To speed things up I thought to chuck and turn short cylinders
without bothering with making tenons. Hollowing the end grain with any
pressure at all made them fly out of the chuck even when it was over
tightened. I relearned what I had unlearned, so I'll caution a few
beginners and remind two lazy oletimers.

George explains it better, but in compression mode although scroll
chucks need to close on a tenon radially, just as or more importantly
the front of the jaws need to firmly abut the radial foot of a tenon.
Clamping, no matter how tightly, a cylinder without a tenon in the the
jaws with its end contacting the chuck body is no good, but if you
insist on doing it, be sure to wear a catcher's mitt and mask.


Turn to Safety, Arch
Fortiter


http://community.webtv.net/almcc/MacsMusings

"Arch" wrote in message
...
It was time to make another thirty or so favors for Lori's Waves & Navy
Nurses monthly luncheon. I chose to make small ring bowls and turned
them from mahogany offcuts and burned a crude fouled anchor in the
bottoms. To speed things up I thought to chuck and turn short cylinders
without bothering with making tenons. Hollowing the end grain with any
pressure at all made them fly out of the chuck even when it was over
tightened. I relearned what I had unlearned, so I'll caution a few
beginners and remind two lazy oletimers.

George explains it better, but in compression mode although scroll
chucks need to close on a tenon radially, just as or more importantly
the front of the jaws need to firmly abut the radial foot of a tenon.
Clamping, no matter how tightly, a cylinder without a tenon in the the
jaws with its end contacting the chuck body is no good, but if you
insist on doing it, be sure to wear a catcher's mitt and mask.


Also a good thing to have that dovetail hooking in and wedging tight. When
you get behind that shaving on the inside, you're pulling against a couple
of foes. http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

On Mon, 29 Oct 2007 11:16:37 -0400, (Arch) wrote:

It was time to make another thirty or so favors for Lori's Waves & Navy
Nurses monthly luncheon. I chose to make small ring bowls and turned
them from mahogany offcuts and burned a crude fouled anchor in the
bottoms. To speed things up I thought to chuck and turn short cylinders
without bothering with making tenons. Hollowing the end grain with any
pressure at all made them fly out of the chuck even when it was over
tightened. I relearned what I had unlearned, so I'll caution a few
beginners and remind two lazy oletimers.

George explains it better, but in compression mode although scroll
chucks need to close on a tenon radially, just as or more importantly
the front of the jaws need to firmly abut the radial foot of a tenon.
Clamping, no matter how tightly, a cylinder without a tenon in the the
jaws with its end contacting the chuck body is no good, but if you
insist on doing it, be sure to wear a catcher's mitt and mask.


Turn to Safety, Arch
Fortiter


http://community.webtv.net/almcc/MacsMusings

I just had a similar experience, Arch..
Turning a goblet out of a 4 x 4 " piece of cocobolo, a foot long... Put it
between centers and rounded and did the basic shape, then put the largest tenon
that my chuck will handle on one end and chucked it.. began hollowing the bowl..

The 3rd time that it either came out of the chuck or wobbled from moving in the
jaws, I figured out that though my tenon was the right diameter and square for
the fit of the jaws, (Oneway chicks don't use a dovetail), the tenon was about
1/16" too LONG...
It was bottoming out in the chuck be by so little that it wasn't really visible
until I checked the depth.. (Sorry, not with a micrometer)

Took it outside and used the disk sander to take about an 1/8" off the bottom of
the tenon and it works fine..
I'm definitely going to keep that in mind on the next 2 goblets!

As you said, hopefully this will help someone out there...



"Experience is the ability to recognize your mistakes when you repeat them"



mac

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