First posted on rec.woodworking - thanks, George - should have guessed that
there was a dedicated bunch of computerised turners.

Anyway:
I've had an axminster clubman chuck for a year or so and have only used it
with the type C jaws. er, this is my first expanding chuck in
case you can't guess from the rest of the post.

These have a dovetail on the outside and a lipped internal grip on the
inside.

http://www.axminster.co.uk/product-A...Jaws-21941.htm

After one or two disasters with the expanding dovetail on bowls where i had
left insufficient wood around the outside of the recess to withstand the
forces - and that the internal recess can be left on the bottom of a bowl
but its not a great feature {George posted a link to one of his which is
giving me second thoughts on this though}- i have tended to use the internal
lipped recess for most stuff and then take off the stub after finishing.

originally i would turn a stepped spigot to fit the lip - but i had one or
two of those fly across the room with the "stepping" bit splitting.
So i took to just doing a straight spigot.

But it tends to slip occasionally.

Two questions then - what does everyone else use - the inside stepped or the
outside dovetail. If you use the inside stepped do you turn a stepped
spigot or a straight one.

And would a different internal shape be better for bowls such as the
serrated one on the type H Medium gripper or the dovetailed ones on the Type
A ? (eg the kids don't know what to get me for xmas...)

Oh if it makes any difference - not just bowls of course - I'm still working
on perfecting the ideal eggcup; have had an enjoyable bash or two at goblets
and everybody seems to be getting boxes this xmas.

Thanks

Ken

"Ken Wilson" wrote in message
...

originally i would turn a stepped spigot to fit the lip - but i had one or
two of those fly across the room with the "stepping" bit splitting.
So i took to just doing a straight spigot.

But it tends to slip occasionally.

Two questions then - what does everyone else use - the inside stepped or
the
outside dovetail. If you use the inside stepped do you turn a stepped
spigot or a straight one.

And would a different internal shape be better for bowls such as the
serrated one on the type H Medium gripper or the dovetailed ones on the
Type
A ? (eg the kids don't know what to get me for xmas...)

Oh if it makes any difference - not just bowls of course - I'm still
working on perfecting the ideal eggcup; have had an enjoyable bash or two
at goblets and everybody seems to be getting boxes this xmas.

Couple of red flags showing here Ken. "stepped dovetail" is impossible.
That ridge under the dovetail is the limit of depth, otherwise you lose the
wedge, and start to try to drive a round peg in a round hole, which makes a
split. You have to bottom the jaws in the recess, that's what takes the
strain. Your wedge action helps draw it snug. You're not gripping, which
is why you don't crank on the tension, you just snug the face of the jaws
against the bottom of the mortise. Make sure it's free of dust and chips,
and the bottom is perpendicular to the axis of rotation so it will seat
without wobbling.

Same principle in gripping outside. What really counts is getting the
shoulder you cut perpendicular to the axis of rotation flat up against the
jaws of the chuck. You can use the dovetail, if your jaws have them, to
wedge, but you don't want any part below the limit of the dovetail to steal
the wedge from you by grabbing the wood.

If you use the serrated type for grip, you will have to snug the piece flat
up against the jaws by using your tailstock or some other type of pressure,
because there's no wedging action to draw for you. You might even end up
pushing the piece out of register if you overtighten the jaws, because the
serrations are really bi-directional wedges, and they'll push up and break
through the fibers if you're not careful.

That's why I like the smooth jaws. When you make the tenon or mortise as
close an approximation of the circle formed by the jaws as possible, you
spread the load over a large surface. Means you won't exceed the elastic
limit of the wood when you snug up.

As you saw in the picture I referenced, you can sneak your hold into a
background of decoration pretty easily. The picture is actually of a
mortise which was used initially, and the outside ridges were held as if a
tenon afterward. Neither made a significant dent, and the piece was about
10" in diameter, yet held for hollowing and sanding just fine.

Think fox-wedged dovetails, or the wedge that holds your hammer head in
place.

"George"
Couple of red flags showing here Ken. "stepped dovetail" is impossible.

Thanks again - this is getting clearer - sorry to be so thick - look i'm an
expert on coffee if I can do the "help desk" bit on that in return :-)

I hadn't appreciated the importance of a squared off shoulder- nor had the
cleanliness occured to me

The jaws I have have a dovetail on the outside edge. They are easy to cut a
hole for but have had the odd split out when i have taken the outside edge
of the turning too close to the recess leaving insufficient wood to hold the
work. So i could get a set of jaws which did smaller external dovetails, i
suppose.

The alternative is the inside holding edge which is not a dovetail but is
parallel and stepped - see
http://www.axminster.co.uk/product-A...Jaws-21941.htm
and then click on the "jaw profiles " bit.

Now - what shape spigot do i make for that? If i understand you i just cut
a straight parallel spigot SHORTER than the total depth of the jaws so it
relies on the shoulder of the wood to be faced flat and not the end of the
wooden spigot - nor do i cut a stepped spigot which i had assumed was the
ultimate profile.

and would i be better with one of the jaws which has a dovetail on the
inside and out
eg
http://www.axminster.co.uk/product-A...Jaws-21939.htm

or
http://www.axminster.co.uk/product-A...Jaws-22836.htm


(i am off the gripper type jaws after realising the sense of your "chews up"
comments)st.


Thanks

ken

"Ken Wilson" wrote in message
...
The alternative is the inside holding edge which is not a dovetail but is
parallel and stepped - see
http://www.axminster.co.uk/product-A...Jaws-21941.htm
and then click on the "jaw profiles " bit.

Now - what shape spigot do i make for that? If i understand you i just
cut a straight parallel spigot SHORTER than the total depth of the jaws so
it relies on the shoulder of the wood to be faced flat and not the end of
the wooden spigot - nor do i cut a stepped spigot which i had assumed was
the ultimate profile.

That profile grips outside with a squared shoulder, short enough depth
(length) of spigot as not to bottom against the inside of the jaws, and a
mild undercut of the point where the spigot meets the shoulder ( /spigot\ )
That way the ridge will find the path of least resistance to be snug up
against the shoulder. Help it when tightening with your tailstock.

and would i be better with one of the jaws which has a dovetail on the
inside and out
eg
http://www.axminster.co.uk/product-A...Jaws-21939.htm

or
http://www.axminster.co.uk/product-A...Jaws-22836.htm


(i am off the gripper type jaws after realising the sense of your "chews
up" comments)st.

I like the A&B type. Just got the similar pattern for my Teknatool NOVA
chuck. They call them 75mm, though the minimum seems to be 82 for a recess,
where they work just fine. Joy is in the broad faces on the jaws, which
allows good wide shouldering of relatively small diameter tenons. Did some
green wood goblets with them, and I'm hooked. The spigot jaws are now in
their own box, like the extra sets of 50mm I acquired along with extra chuck
bodies rather than in their compartment in the drawer. I'll be using them
even less than I did before, which was hardly ever.

As to the grip types, there are those out there who swear by them rather
than at them as I do. More suitable to dry wood than green, and they do
grip square stock well. Mine were out of the box for a few ornaments a
month ago for that reason. The O'Donnell type are nice for people who do
wine stoppers, tops and such in a production environment, but my choice
would be http://www.axminster.co.uk/product-A...Jaws-23111.htm
for that type of spigot use and as pin jaws for roughing out. Most useful
type of jaw for general work I own.

"George"

Got it.
thanks for being so patient

:-)

ken

For what its worth...

What George said is about the same way I use my Nova 2 jaws.

Been using them for about a year now and this chuck and jaws are worth
every penny.

On small light bowls and vessels I counterbore the first end of my
bowl, chuck it with the outside dovetail of the jaws. Turn the bottom
and outside. With that same mount I turn a shallow hole on the bottom
(foot) of my bowl and give the wall of the hole slight dovetail angle.

Then dismount, turn the bowl around, and mount the bowl in the dovetail
hole I made in the foot, and finish my bowl on this second mount.

On larger heavier bowls and vessels, I turn a spigot that is near the
maximum opening size of my powergrip jaws. I also turn a step at the
end of the spigot, so the ends of the jaws has something square to butt
up against when I mount on the spigot.

One good tip.

Once you have your work mounted on the jaws, and it is turning
perfectly round, mark the bowl right next to a mark on your jaw. This
will give you a reference so that if you have to dismount your bowl you
can remount it at the same spot you had it before reducing the chance
of mounting it out of round the next time.

On spigots, this is far easier because the spigot will be a waste
piece. On spigots I use a sharpie pen and mark the wood on the spigot
where it shows in between the jaws. Spigot jaws will leave impressions
on the wood as well, so you will want to "feel" your block back into
the same spot when remounting.

cad
hanturnedbowls.biz

Ken Wilson wrote:
First posted on rec.woodworking - thanks, George - should have guessed that
there was a dedicated bunch of computerised turners.

Anyway:
I've had an axminster clubman chuck for a year or so and have only used it
with the type C jaws. er, this is my first expanding chuck in
case you can't guess from the rest of the post.

These have a dovetail on the outside and a lipped internal grip on the
inside.

http://www.axminster.co.uk/product-A...Jaws-21941.htm

After one or two disasters with the expanding dovetail on bowls where i had
left insufficient wood around the outside of the recess to withstand the
forces - and that the internal recess can be left on the bottom of a bowl
but its not a great feature {George posted a link to one of his which is
giving me second thoughts on this though}- i have tended to use the internal
lipped recess for most stuff and then take off the stub after finishing.

originally i would turn a stepped spigot to fit the lip - but i had one or
two of those fly across the room with the "stepping" bit splitting.
So i took to just doing a straight spigot.

But it tends to slip occasionally.

Two questions then - what does everyone else use - the inside stepped or the
outside dovetail. If you use the inside stepped do you turn a stepped
spigot or a straight one.

And would a different internal shape be better for bowls such as the
serrated one on the type H Medium gripper or the dovetailed ones on the Type
A ? (eg the kids don't know what to get me for xmas...)

Oh if it makes any difference - not just bowls of course - I'm still working
on perfecting the ideal eggcup; have had an enjoyable bash or two at goblets
and everybody seems to be getting boxes this xmas.

Thanks

Ken

"cad" wrote in message
ups.com...
Once you have your work mounted on the jaws, and it is turning
perfectly round, mark the bowl right next to a mark on your jaw. This
will give you a reference so that if you have to dismount your bowl you
can remount it at the same spot you had it before reducing the chance
of mounting it out of round the next time.

Oddly,the chief advantage to the smooth jaws is they _must_ mount true. They
have no other choice if you keep the mating surfaces clean and undamaged.
Any place around the inside of the mortise or the outside of the tenon is
equal to any other. If the first attempt on a reverse or remount doesn't
rotate true, I consider it a clue that I have a shaving or something
captured, and re-check. Not all that unusual that I use the recess or
groove that that forms the bottom to re-mount a bowl whose finish I'm not
satisfied with for shaving off the old finish to try again. Some get pretty
thin, but by not eliminating my mount, I still have the capability. That's
where I use the power-grip jaws the most, in scribed and perhaps burned
rings which form the reveal at the bottom of a bowl. By turning them a close
match, I get a second chance. Do hate having to work around the tailstock
for the back, but it's doable.

Do your jaws meet flush on the front? That and using your tailstock as a
bumper/clamp on the inside of an already turned bowl.

I've got one of the NOVA live centers which allows me to screw on tapered
disks to wedge and center where I can't extend the quill all the way to the
bottom.