Mahogany Bowl Mishap

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Barry N. Turner

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Aug 6, 2005, 11:26:51 PM8/6/05
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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?


william_b_noble

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Aug 6, 2005, 11:55:48 PM8/6/05
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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" <barr...@bellsouth.net> wrote in message
news:PvfJe.19261$jq.1...@bignews3.bellsouth.net...

Delbert Freeman

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Aug 7, 2005, 12:30:55 AM8/7/05
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Barry N. Turner wrote:

It maybe. Your problem sounds like one my grandson and I ran into today.
We were turning an 11" bowl out of cedar with a recess to put an expansion
chuck in. The recess broke out after we had reversed the bowl and locked
the bowl on the expansion chuck. What we did was find center of of the
recess and remounted it between centers, but used the chuck on the
headstock. Turned a new recess a bit larger with a bit thicker sidewall.
Worked well.

Deb

Barry N. Turner

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Aug 7, 2005, 10:05:27 AM8/7/05
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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" <nob...@nowhere.com> wrote in message
news:1123386949.3a18ea4a5d8508ba8b70563ec96ba00f@teranews...

M.J.

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Aug 7, 2005, 12:17:30 PM8/7/05
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Barry,
I assume that right up to the point where you had the "catch" your tenon
was doing it's job. It was not a question of how big the tenon was or
whether you should have used a mortise. The "problem" was the "catch. If
you intend to continue having "catches" then I suggest you get bigger jaws
for turning 10 inch bowls. If not then I suggest you analyze exactly what
caused your catch and do everything you can to avoid presenting the tool to
the wood in that fashion again. Makes more sense than getting a "Tim the
Tool Man" set of jaws for a very small bowl. IMHO of course......I could be
wrong...... ;^)

--

Regards,
M.J. (Mike) Orr
www.island.net/~morr


"Barry N. Turner" <barr...@bellsouth.net> wrote in message
news:PvfJe.19261$jq.1...@bignews3.bellsouth.net...

Leif Thorvaldson

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Aug 7, 2005, 3:57:12 PM8/7/05
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"M.J." <newst...@xemaps.com> wrote in message
news:dd5c6...@enews1.newsguy.com...

> Barry,
> I assume that right up to the point where you had the "catch" your
> tenon was doing it's job. It was not a question of how big the tenon was
> or whether you should have used a mortise. The "problem" was the "catch.
> If you intend to continue having "catches" then I suggest you get bigger
> jaws for turning 10 inch bowls. If not then I suggest you analyze exactly
> what caused your catch and do everything you can to avoid presenting the
> tool to the wood in that fashion again. Makes more sense than getting a
> "Tim the Tool Man" set of jaws for a very small bowl. IMHO of
> course......I could be wrong...... ;^)

=====> Don't listen to him, Barry! Now you have a half-ways decent excuse
to buy another chuck!!! Every real turner should have three or four at
least.*G*

Leif


Martin H. Eastburn

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Aug 7, 2005, 9:06:50 PM8/7/05
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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:


--
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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Patriarch

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Aug 8, 2005, 1:36:09 AM8/8/05
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"Leif Thorvaldson" <Le...@mashell.com> wrote in
news:11fcps7...@corp.supernews.com:

Now I can understand how I might use two chucks on a bowl. Explain three
or four, please.

Patriarch

Leif Thorvaldson

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Aug 8, 2005, 2:48:48 AM8/8/05
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"Patriarch" <gma...@nospam.comcast.dot.net> wrote in message
news:Xns96ABE5E4FB56Apa...@216.196.97.136...

*SIGH!* Of all people, Patriarch, I would have believed you would
immediately comprehend the significance of possessing more than two chucks.
To explain: I have more than one bowl gouge (different sizes, eh?), more
than two clamps (different sizes, different clamping features, eh?), etc.
Now you see where I am going with this? Since I now have more than two
chucks and can only use two at the most on my single lathe -- it stands to
reason that I need an additional lathe to go with the chucks. QED,
eh?Omigawd, stop me someone!! And, I am even starting to sound like a
Canadian, eh? *G*

Leif


Kevin

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Aug 8, 2005, 10:44:16 AM8/8/05
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I am uncertain if it translates over to your situation but some time back I
recall reading that if you use a faceplate the largest diamter would be no
more than 3 X the isze of the faceplate, i.e., a 3" faceplate would allow
the turning of a 9" diameter bowl.
Also, as others have mentioned, a large factor in the determination of the
size of the tenon would be the nature of the wood itself. Hope all turns
out well.

"Barry N. Turner" <barr...@bellsouth.net> wrote in message
news:PvfJe.19261$jq.1...@bignews3.bellsouth.net...

mac davis

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Aug 8, 2005, 12:10:25 PM8/8/05
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On Sat, 6 Aug 2005 20:55:48 -0700, "william_b_noble" <nob...@nowhere.com> wrote:

>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)
>

thanks, Bill.. that's exactly what I was trying to say in the prior post, but
the words weren't forming... I need more coffee!


>"Barry N. Turner" <barr...@bellsouth.net> wrote in message
>news:PvfJe.19261$jq.1...@bignews3.bellsouth.net...
>>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?
>>
>>
>

mac

Please remove splinters before emailing

mac davis

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Aug 8, 2005, 12:13:15 PM8/8/05
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On Mon, 08 Aug 2005 00:36:09 -0500, Patriarch <gma...@nospam.comcast.dot.net>
wrote:

He probably has 2 or 3 soaking in LDD to prevent jaw cracks....

Leo Van Der Loo

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Aug 8, 2005, 3:47:54 PM8/8/05
to
Hi Mac

They better not be those cheap ones or they be all rusted
together,....... come to think of it, that would make the LDD just right
for wood staining at the same time ?? yes?? no ??

Have fun (at the expense off) and take care
Leo Van Der Loo

mac davis wrote:

> > SNIPPEDY SNIP

Leif Thorvaldson

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Aug 8, 2005, 6:22:20 PM8/8/05
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"Leo Van Der Loo" <l.van...@rogers.com> wrote in message
news:cLudnYaFmo9...@rogers.com...

====>Scoff all you like, gentlemen! I have had one chuck gripping the tenon
of the bowl that I immersed in LDD. I kept the chuck out of the LDD
solution and just dangled the bowl in it while I was busy turning another
bowl mounted on a second chuck. As to chucks 3 & 4, they are only figments
of my imagination. Since I am no longer married, I have no good woman to
agree with me that I need more chucks and thereby, allow me to spend the
money. You guys are so lucky! *G*

Leif


Barry N. Turner

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Aug 8, 2005, 10:55:58 PM8/8/05
to
Barring tremendous catches, I think a 2" tenon would be perfectly adequate
for a 10" bowl.

I think I have gotten myself out of this mess. Last night, I used medium
viscosity CA glue and re-attached the tenon to the bowl. I finished
hollowing without mishap tonight. I have power sanded the exterior and
interior of the bowl. Now all that remains is to reverse the bowl and turn
the foot, which should be fairly straight forward. God bless the guy(s) who
invented CA glue.

Barry

"Kevin" <skl...@hotmail.com> wrote in message
news:dd7r42$5oq$1...@rainier.uits.indiana.edu...

Leif Thorvaldson

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Aug 9, 2005, 12:58:51 AM8/9/05
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"Barry N. Turner" <barr...@bellsouth.net> wrote in message
news:IUUJe.947$3p....@bignews3.bellsouth.net...

> Barring tremendous catches, I think a 2" tenon would be perfectly adequate
> for a 10" bowl.
>
> I think I have gotten myself out of this mess. Last night, I used medium
> viscosity CA glue and re-attached the tenon to the bowl. I finished
> hollowing without mishap tonight. I have power sanded the exterior and
> interior of the bowl. Now all that remains is to reverse the bowl and
> turn
> the foot, which should be fairly straight forward. God bless the guy(s)
> who
> invented CA glue.
>
> Barry

====>CA courtesy of the NASA Space Program. You'd think they might use some
of it to hold their insulation and tiles on, though!! Only a billion dollars
spent so far on solving the problem and they still come loose!

Leif


Lee Michaels

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Aug 9, 2005, 2:11:45 AM8/9/05
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"Leif Thorvaldson" <Le...@mashell.com> wrote

>
> ====>CA courtesy of the NASA Space Program. You'd think they might use
> some of it to hold their insulation and tiles on, though!! Only a billion
> dollars spent so far on solving the problem and they still come loose!


I wonder what type of duct tape they could have come up with for a billion
dollars.

George

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Aug 9, 2005, 7:02:12 AM8/9/05
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"Lee Michaels" <leemi...@comcast.net> wrote in message
news:RNudnfY4q6u...@comcast.com...
"Duck" is the proper term, and I think the Military let the spec for it
during WWII. Don't use it for taping your HVAC ducting. Much better stuff
out there for that.


Alun

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Aug 9, 2005, 7:37:51 AM8/9/05
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George

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Aug 9, 2005, 9:30:42 AM8/9/05
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"M.J." <newst...@xemaps.com> wrote in message
news:dd5c6...@enews1.newsguy.com...
> Barry,
> I assume that right up to the point where you had the "catch" your
> tenon was doing it's job. It was not a question of how big the tenon was
> or whether you should have used a mortise. The "problem" was the "catch.
> If you intend to continue having "catches" then I suggest you get bigger
> jaws for turning 10 inch bowls. If not then I suggest you analyze exactly
> what caused your catch and do everything you can to avoid presenting the
> tool to the wood in that fashion again. Makes more sense than getting a
> "Tim the Tool Man" set of jaws for a very small bowl. IMHO of
> course......I could be wrong...... ;^)
>

Tried to avoid my oft-expressed opinion here, so as not to sound a Leif (LDD
anyone?), but here it goes again. The width of the shoulder that the jaws
ride against, and the proper registry against the shoulder are the most
important factors in holding the piece. That way it isn't just the tenon
length you have to lever against, but the shoulder, too. Since the
shoulder is perpendicular to the angle of a proper cut, and extends farther
from the point of rotation, it has the greatest mechanical advantage.

Weakness of destructive grips - non wedge types - is that they are as likely
as not to push the nose of the jaws out of register with the shoulder as
into. With a dovetail, the wedge draws tight up against the shoulder,
whether that is an innie or an outie.

Then there's the tailstock issue....


Leif Thorvaldson

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Aug 9, 2005, 10:23:48 AM8/9/05
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"Alun" <not...@notsaunders.net> wrote in message
news:11fh5cf...@news.supernews.com...

====>Alun's due diligence in finding the history of "duck" tape, caused me
to do basically the same thing. I must apologize to the group, but Leif was
wrong! Oh the shame of it all! To wit:
"History of Super Glue
Since its heralded beginning, the powerful adhesive known as Super Glue has
enjoyed a rich history - including an imaginative element of mythology!
Though urban legend describes the glue as an accidental solution to battle
wounds during World War II, its actual evolution is a little different.

The original cyanoacrylates (the chemical name for the glue) were discovered
in 1942 in a search for materials to make clear plastic gun sights for the
war, and scientists stumbled upon a formulation that stuck to everything
that it came in contact with. However, cyanoacrylates were quickly rejected
by American researchers precisely because they stuck to everything! In 1951,
cyanoacrylates were rediscovered by Eastman Kodak researchers Harry Coover
and Fred Joyner, who recognized its true commercial potential, and it was
first sold as a commercial product in 1958.

We are proud to have Super Glue in our extensive family of products and look
forward to the future evolution of this magical adhesive!

The Story Behind the Hanging Car - Super Glue Corporation Logo:

A radio station had heard about super glues and decided to put them to the
test at a local junk yard. Among the super glues tested were many of the
National Brands on the market today. The test was to hold a hanging car from
a crane and the Super Glue Corporation product was the best! (Some of our
competitor's currently have "hanging things" like people, & television sets,
but nothing compares to the strength of our hanging car.)"

http://www.supergluecorp.com/history.html

Leif


Harry Pye

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Aug 9, 2005, 11:47:14 AM8/9/05
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> I wonder what type of duct tape they could have come up with for a billion
> dollars.

Probably the same substrate and adhesive but in twenty designer colors!

M.J.

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Aug 9, 2005, 12:15:25 PM8/9/05
to


"George" <George@least> wrote in message
news:42f8a...@newspeer2.tds.net...


> Tried to avoid my oft-expressed opinion here, so as not to sound a Leif
> (LDD anyone?), but here it goes again.

Too late George!

>The width of the shoulder that the jaws ride against, and the proper
>registry against the shoulder are the most important factors in holding the
>piece.

So.......... This is "news"

That way it isn't just the tenon
> length you have to lever against, but the shoulder, too. Since the
> shoulder is perpendicular to the angle of a proper cut, and extends
> farther from the point of rotation, it has the greatest mechanical
> advantage.
>
> Weakness of destructive grips - non wedge types - is that they are as
> likely as not to push the nose of the jaws out of register with the
> shoulder as into.

VERY simple to do with my "destructive" jaw sets. Surprised you haven't
figured out how to do it by now..... Hard to stop laughing at this
one..........Chuckle..... I just love some of your "theories"......


With a dovetail, the wedge draws tight up against the shoulder,
> whether that is an innie or an outie.

Of course you have done extensive tests to prove your "theory" that
destructive jaws=bad (read Oneway here) George's jaws=good.....?

>
> Then there's the tailstock issue....

Why? Didn't your lathe come with one............???? :-)

Barry N. Turner

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Aug 14, 2005, 8:08:55 AM8/14/05
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Who says NASA and the Space Program aren't worthwhile?

Barry


"Leif Thorvaldson" <Le...@mashell.com> wrote in message
news:11fgdvo...@corp.supernews.com...

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