Greetings,

Has anyone tried something like this for holding segments tightly
together for glue-ups? I use a band clamp now, but was just thinkin'.

http://webpages.charter.net/videodoctor/segmentjig2.htm

The silver things are threaded rods with a handle (not shown).
A jig this size, 16" x 16" could glue up everything from a 2" diameter
to a 12" diameter ring. Not shown is the round cawl that screws down
over the whole mess when finished, to keep the rings flat against the
bed of the jig.

You could set-up the positions of everything before gluing, rotate
each screw out 1 turn, glue a segment, replace - ad nauseam - and then
tighten the screws again to achieve even pressure and a one-time
glue-up. If you work very fast, that is... You could really put the
squeeze on a ring with this thing.

Aside from the 6 feet of all-thread and construction time, I wonder if
this would work well enough to bother building...?

Thanks,


Greg G.

Check this page out, he uses rubber bands:
http://www.turnedwood.com/FrameMiterBowl.html

Greg G. wrote:


Aside from the 6 feet of all-thread and construction time, I wonder if
this would work well enough to bother building...?


AHA! Another gadgeteer trying to re-invent the wheel, eh? ;-)

I can't see much wrong with the idea, although I think it would be kind
of cumbersome. You'd probably want it on a turntable (lazy susan bearing
thingy) since you'll have to tighten each rod a little at a time, evenly
all around. The ends of the rods may want to put a twisting force on the
segments as the pressure is increased, but a clamp disk on top will help
deal with that. Instead of flat ends on the rods, I'd grind them with a
rounded point or maybe just slightly convex would be good enough.
You'll need to somehow keep that clamp disk from being glued to the
segment ring--wax it, or?
Shouldn't take more than a couple hours to slap together, I say go ahead
and try it. But there are other ways, less cumbersome--many segmented
turners use band clamps, large hose clamps, or rope tournequets. If your
segment angles are right on, that kind of circumferential pressure will
do just fine. You may still need a clamp plate, but will only have one
screw or twister-stick to tighten instead of 12.

Ken Grunke
http://www.token.crwoodturner.com/

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I've thought of that, but IMHO the pressure points need to be at the
seams, not the faces, with V-shaped blocks, so that the pressure keeps
the faces lines up.

OTOH, I was thinking about servo-actuated clamps, so that the computer
can keep them in sync. I suppose a simple ring gear system, like the
supernove chuck uses, would work too. Sixteen jaw chuck anyone?
Maybe a longworth chuck? You'd need a top plate to keep the pins
aligned though.

"Greg G." wrote: (clip) Aside from the 6 feet of all-thread and
construction time, I wonder if this would work well enough to bother
building...?
^^^^^^^^^^^^^
First, Greg, I want to compliment you on a really nice job of graphics. Now
to the nutz and boltz. Two lengths of All-thread are very cheap. But, you
will also have to have a matching threaded insert for each piece of
All-thread to go into. And, what about some means of turning the threads?
Surely you are not going to make a beautiful jig like this, and then use
pliers.

My reaction is that it is too much work, to solve a problem that has already
been solved with a simple band clamp.

How about arranging the rods so they slide instead of screw and form them in
a U that connects to a scroll chuck underneath and tightens them all at one
time and makes them all self centering.

Brian

Greg G. said:

Has anyone tried something like this for holding segments tightly
together for glue-ups? I use a band clamp now, but was just thinkin'.
snip

Thanks, everyone, for the suggestions.
I use strap/band clamps now, but had a moment of idle time to ponder
other possibilities. I'm with Kurt Vonnegut on this one - consider
your options.

It only took a few minutes to create the CAD drawing.
Yes, knobs would have been included - I just didn't feel he need to
draw them, (Dawr them - for you Bostonians.)

Tightening all those screws is a bit much - but servo mechs, although
interesting from an engineering standpoint, are not practical.
Pneumatic clamps, however... Hmm...

Gadgeteer? Absolutely. It's my reason for living... g
Just Another Gadgeteer? Never! Reinventing the wheel?
Nah, just searching for another way to do something more efficiently.

I think this particular project is not practical, but after gluing up
a few more rings last night, I think I've got another bonehead idea...

FWIW,

Greg G.