Hi

Does the recess have to be perfect. I have a nova compact chuck. Currently
no matter what I try to secure the chuck to the wood, I can tighten enough
to keep the wood secure. I believe that i have the correct angle.Maybe the
cut isn,t clean enough.

Any suggestions
Keith

You're thinking in the wrong direction. You make the recess so that the
chuck jaws wedge themselves against the bottom of the recess, not the sides.
Woodworking 090 tells you don't try to put a round peg/nail/chuck in a round
hole in wood, it'll split.

Thought I had sent you a reference to my page where the standard NOVA is
used, but in case not,
try. http://personalpages.tds.net/~upgeorge/index.html and look at the
methods, using recesses. You want to keep the area where the jaw faces meet
the bottom of the bowl smooth, and free of dust. Further, especially with
wet wood, or weak sapwood, reinforce with water-thin CA, remembering to
scrape irregularities with your skew or clean up with your pointy gouge to
get a nice wedge.

"Keith Young" wrote in message
...
Hi

Does the recess have to be perfect. I have a nova compact chuck.
Currently
no matter what I try to secure the chuck to the wood, I can tighten enough
to keep the wood secure. I believe that i have the correct angle.Maybe the
cut isn,t clean enough.

Any suggestions
Keith

You want the dovetail in the wood to have at least as acute an angle
as the dovetail on the chuck - but since it is unlikely you'll match
the angle perfectly, make the dovetail in the wood more acute than
that of the chuck. If the point of the chuck's dovetail contacts the
wood and the rest of the metal dovetail isn't in firm contact with the
wood the wood piece will wobble and come loose. Better to have the
point of the metal dovetail not in contact and the metal side and
bottom contact the wood further back. That way you have two firm
points of contact all the way around and the more you tighten the
chuck the more these points of contact come to bear. This gives you a
firm grip on the wood.

In the ascii scetch below, imagine the inner part (the chuck) in
actual contact with the bottom and you get the idea.

/
/ /
/ /
/ /________
---------------

On Wed, 27 Oct 2004 10:02:07 -0230, "Keith Young"
wrote:

Yes I am a newfoundlander and we have some very excellent woodturners here
in this province.

"Keith Young" wrote in message
...
Hi

Does the recess have to be perfect. I have a nova compact chuck. Currently
no matter what I try to secure the chuck to the wood, I can tighten enough
to keep the wood secure. I believe that i have the correct angle.Maybe the
cut isn,t clean enough.

Any suggestions
Keith

Keith

I have found that I get better results when I use a tennon instead of a
recess - the chuck can get a bettr bit in the compression mode versus the
expansion mode - you may want to try using a tennon and then jam chucking
the bowl to finish the bottom

Ray


"Keith Young" wrote in message
...
Hi

Does the recess have to be perfect. I have a nova compact chuck. Currently
no matter what I try to secure the chuck to the wood, I can tighten enough
to keep the wood secure. I believe that i have the correct angle.Maybe the
cut isn,t clean enough.

Any suggestions
Keith

Thanks George. Wrong direction heh.

Thanks again.

Keith
"George" george@least wrote in message
...
You're thinking in the wrong direction. You make the recess so that the
chuck jaws wedge themselves against the bottom of the recess, not the
sides.
Woodworking 090 tells you don't try to put a round peg/nail/chuck in a
round
hole in wood, it'll split.

Thought I had sent you a reference to my page where the standard NOVA is
used, but in case not,
try. http://personalpages.tds.net/~upgeorge/index.html and look at the
methods, using recesses. You want to keep the area where the jaw faces
meet
the bottom of the bowl smooth, and free of dust. Further, especially with
wet wood, or weak sapwood, reinforce with water-thin CA, remembering to
scrape irregularities with your skew or clean up with your pointy gouge to
get a nice wedge.

"Keith Young" wrote in message
...
Hi

Does the recess have to be perfect. I have a nova compact chuck.
Currently
no matter what I try to secure the chuck to the wood, I can tighten
enough
to keep the wood secure. I believe that i have the correct angle.Maybe
the
cut isn,t clean enough.

Any suggestions
Keith

Keith Young wrote:
Does the recess have to be perfect. I have a nova compact chuck. Currently
no matter what I try to secure the chuck to the wood, I can tighten enough
to keep the wood secure. I believe that i have the correct angle.Maybe the
cut isn,t clean enough.

Keith,
some more information might be helpful, like the type of wood, its
green/dry status, bowl size, and the diameter and depth of the recess.
Does the bowl fall off of its own accord, or does it take a catch

In my experience the diameter of the recess is more important than the
angle of the dovetail. I say that because I do a lot of first fixings
into a shallow hole drilled with a forstner bit, so I have no dovetail
at all. Remember that the jaws have only one true diameter, that is when
they form a true circle. When expamded beyond that diameter they grip
only at the center of their arc, and at smaller diameters they grip at
the ends of their arc.

One other tip is to make sure the chuck is clean of dust and operates
smoothly and easily. If it gets gummed up, a lot of the power you apply
to the key is expended overcoming friction, and it is difficult to get
any feel for how tight the jaws are. You really shouldn't have to crank
too hard on the key to hold a bowl. I periodically blow all the sanding
dust out of the chuck and give the threads a little graphite lubricant.
The jaws should then operate with just the lightest touch.

For final fixing I make the dovetail with a small detail gouge so the
edges are nice and clean. The bottom of the recess is finished with a
flat scraper, the finished shape of the recess erring towards concave.


--
Derek Andrews, woodturner

http://www.seafoamwoodturning.com
Wedding Favors ~ Artisan Crafted Gifts ~ One-of-a-Kind Woodturning

[Posted and mailed]


"Keith Young" wrote in message
...
Hi

Does the recess have to be perfect. I have a nova compact chuck. Currently
no matter what I try to secure the chuck to the wood, I can tighten enough
to keep the wood secure. I believe that i have the correct angle.Maybe the
cut isn,t clean enough.

Any suggestions
Keith




To make the recess as secure as possible, cut it only just large enough
to accept the closed jaws. Under cut the recess to form a wedge shape
so the jaws do not slip out. mount on the jaws and open them to tighten
against the recess wall. this way you will have almost continuous
contact with the wood giving a tighter hold with less stress on any
point of the recess, with no jaw marks inside the recess. If you use a
larger recess there will be limited contact between the jaws and the
recess walls with the risk of the wood flying off - CATCH!!!
--
Dave Lawson

Doesn't seem to make a difference if you bottom it. Or at least it doesn't
at my house.

"David S Lawson" wrote in message
...

To make the recess as secure as possible, cut it only just large enough
to accept the closed jaws. Under cut the recess to form a wedge shape
so the jaws do not slip out. mount on the jaws and open them to tighten
against the recess wall. this way you will have almost continuous
contact with the wood giving a tighter hold with less stress on any
point of the recess, with no jaw marks inside the recess. If you use a
larger recess there will be limited contact between the jaws and the
recess walls with the risk of the wood flying off - CATCH!!!
--
Dave Lawson

Only if you don't bottom it. I assume you are doing so (as I do also) with
your first fixing.

The jaws don't need to "grip" anything unless you're using them in a
non-dovetail recess. Check the pin jaw setup at the pages I referenced.
Even there, the difference is in the bottoming.

"Derek Andrews" wrote in message
...
In my experience the diameter of the recess is more important than the
angle of the dovetail. I say that because I do a lot of first fixings
into a shallow hole drilled with a forstner bit, so I have no dovetail
at all.


SNIP

You really shouldn't have to crank
too hard on the key to hold a bowl.

Follow-up. The pin jaws on the NOVA are circular at 1.125", the maximum
depth of dovetail is 3/16. Quick math, verified after getting back from the
ambulance garage shows a maximum jaw edge only contact area of .663 sq
inches. Jaw faces are slightly greater than .25 broad, offering a contact
area of 2.76 sq inches. In reality, reduce each by about 15% for gaps.

More to the point, the mechanical advantage of the .5625 arm resists
movement much better than the .1875 at nearly right angles to it, especially
when the force of cutting is nearly perpendicular to it when running from
bottom to rim or rim to bottom. I would never recommend an edge presented
perpendicular to the axis of rotation.

Bottom those jaws, that's where the money is.

"George" george@least wrote in message
...
Only if you don't bottom it. I assume you are doing so (as I do also)
with
your first fixing.

The jaws don't need to "grip" anything unless you're using them in a
non-dovetail recess. Check the pin jaw setup at the pages I referenced.
Even there, the difference is in the bottoming.

"Derek Andrews" wrote in message
...
In my experience the diameter of the recess is more important than the
angle of the dovetail. I say that because I do a lot of first fixings
into a shallow hole drilled with a forstner bit, so I have no dovetail
at all.


SNIP

You really shouldn't have to crank
too hard on the key to hold a bowl.

I have found that I get better results when I use a tennon instead of a
recess - the chuck can get a bettr bit in the compression mode versus the
expansion mode - you may want to try using a tennon and then jam chucking
the bowl to finish the bottom

With my Nova chuck (although the original author has a compact version), I
get MUCH better grip in expansion vs. compression. Don't get me wrong, the
compression is great, but in expansion, I get more solid holding with less
visible marring of the wood.

I rarely, if ever, make the recess (or a tenon, for that matter) the full
depth of the jaw's dovetail. I just make sure that the angle of the
recess/tenon is such that the farthest point of the dovetail is what makes
contact first, and then things go great. Good enough, in fact, that a year
or so ago when I first tried purpleheart and made a rather stupid mistake, I
broke the tenon off of the piece before the grip of the chuck gave up.

steve

I'm just the opposite. I've never had very good success with the nova chuck
in expansion mode. I turn everything with a tennon and never had one come
loose. I've broken the wood with a catch using both methods so neither
seems to have an advantage there for me. Do you think our different
experiences are related to our turning methods or just coincidence?
Tony Manella
ndd1"at"prolog.net (remove "at")
http://home.ptd.net/~ndd1/
Lehigh Valley Woodturners
http://www.lehighvalleywoodturners.com/

"Steve Wolfe" wrote in message
...
I have found that I get better results when I use a tennon instead of a
recess - the chuck can get a bettr bit in the compression mode versus
the
expansion mode - you may want to try using a tennon and then jam
chucking
the bowl to finish the bottom

With my Nova chuck (although the original author has a compact version),
I
get MUCH better grip in expansion vs. compression. Don't get me wrong,
the
compression is great, but in expansion, I get more solid holding with less
visible marring of the wood.

I rarely, if ever, make the recess (or a tenon, for that matter) the
full
depth of the jaw's dovetail. I just make sure that the angle of the
recess/tenon is such that the farthest point of the dovetail is what makes
contact first, and then things go great. Good enough, in fact, that a
year
or so ago when I first tried purpleheart and made a rather stupid mistake,
I
broke the tenon off of the piece before the grip of the chuck gave up.

steve

I'm just the opposite. I've never had very good success with the nova
chuck
in expansion mode. I turn everything with a tennon and never had one come
loose. I've broken the wood with a catch using both methods so neither
seems to have an advantage there for me. Do you think our different
experiences are related to our turning methods or just coincidence?

Without having seen each other's turning methods, it's hard to say. : )

I should say that the difference I get isn't so much because the chuck
itself grips better in either mode, but because when I turn in expansion, I
usually have better geometry on the wood. Like you, I've had the tenon
break before the chuck gave out - but the way I use it in expansion, there's
typically more wood behind the grip, so to speak, and I've never had a break
that way.

steve

Hi Steve,
When I have a failure in expansion mode it is usually the wood that breaks
out rather than anything with the chuck. Must just be my style of turning.
Tony Manella
ndd1"at"prolog.net (remove "at")
http://home.ptd.net/~ndd1/
Lehigh Valley Woodturners
http://www.lehighvalleywoodturners.com/

"Steve Wolfe" wrote in message
...
I'm just the opposite. I've never had very good success with the nova
chuck
in expansion mode. I turn everything with a tennon and never had one
come
loose. I've broken the wood with a catch using both methods so neither
seems to have an advantage there for me. Do you think our different
experiences are related to our turning methods or just coincidence?

Without having seen each other's turning methods, it's hard to say. : )

I should say that the difference I get isn't so much because the chuck
itself grips better in either mode, but because when I turn in expansion,
I
usually have better geometry on the wood. Like you, I've had the tenon
break before the chuck gave out - but the way I use it in expansion,
there's
typically more wood behind the grip, so to speak, and I've never had a
break
that way.

steve

As easy as 1,2,3.

1) The way to low stress turning is to cut the wood as it wishes to be cut.
When you do that, the chips fall where they are released from the piece,
they do not fly. If not so, make it so.

2) Energy does equal Mass times velocity squared, so turn at slow speeds,
making less energy available to stress the recess in the event of a catch.
You need only the energy required to sever the fibers, and have instant
feedback from the shavings, which should present a clean edge as they are
released - long side smooth.

3) Remember that the recess is just a means for wedging the face of the jaws
snugly into the bottom of the piece. You need snug, not tight. Tight is
the same as forcing a round peg into a round hole - it splits wood. That's
why nails are clipped, pegs are rough whittled, or square.

Some available techniques at
http://personalpages.tds.net/~upgeorge/index.html

"Tony Manella" ndd1 at prolog.net wrote in message
...
Hi Steve,
When I have a failure in expansion mode it is usually the wood that breaks
out rather than anything with the chuck. Must just be my style of
turning.

To turn endgrain N.I.Pine, I use a faceplate, waste some wood and
complete the piece without reversing. It's academic, but If I did use a
scroll chuck on softer timber would it not be better to expand the jaws
toward the stronger periphery instead of compressing toward the log's
weaker soft center or mushy pith? I'd think that compressing a tenon or
expanding into a dovetail would largely depend upon whether the center
or the periphery is strongest.

For first holding on/in a dovetail which doesn't allow the blank to
reach the chuck body or base of the jaws, what determines the blank's
axis; the axis of the dovetail walls or the face that the jaw's forward
rims register against? OK to sigh, but don't groan.

Turn to Safety, Arch

Fortiter,


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

Hi there Arch

Arch ,my opinion, if everything's equal, the larger surface has the most
strength, that's the outside.
The other thing is, give me the oneway chuck jaws, they hold better
hands down.

Have fun and take care
Leo Van Der Loo

http://homepage.mac.com/l.vanderloo/PhotoAlbum12.html


Arch wrote:

To turn endgrain N.I.Pine, I use a faceplate, waste some wood and
complete the piece without reversing. It's academic, but If I did use a
scroll chuck on softer timber would it not be better to expand the jaws
toward the stronger periphery instead of compressing toward the log's
weaker soft center or mushy pith? I'd think that compressing a tenon or
expanding into a dovetail would largely depend upon whether the center
or the periphery is strongest.

For first holding on/in a dovetail which doesn't allow the blank to
reach the chuck body or base of the jaws, what determines the blank's
axis; the axis of the dovetail walls or the face that the jaw's forward
rims register against? OK to sigh, but don't groan.

Turn to Safety, Arch

Fortiter,


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