Gouge dimensions puzzlement

Mark Schecter

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Jun 17, 2001, 2:16:09 PM6/17/01

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Hi all.

I was just puttering around the shop and tools, and decided to measure my
bowl gouge. It's a Sorby HSS bowl gouge, with the deep curved U-shaped
flute ala Ellsworth, which is great and I love it. But I can't make sense
of the markings.

It is clearly marked 13mm-1/2". Now I (think I) know that the English
system measures across the flute, while the Americans measure the diameter
of the shank, regardless of machined features. (Is that right?)

Here are the dimensions I measured with my trusty dial caliper, which reads
in both inches and millimeters.

mm inch
shaft diameter 16 .630 (about 5/8")
flute width 10.2 .4
flute depth 8.9 .352 (about 3/8")
shaft thickness
at flute
bottom 5.2 .205 (< 1/4")

Nowhere do I find 13mm-1/2". Again, I love this gouge, so I'm not feeling
"gouged." But can anyone explain either the markings or the measurements? Thanks!

Mark Schecter
Oaktown Calif.

Grusserry

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Jun 17, 2001, 3:44:50 PM6/17/01

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Only on tools that are made in US or Canada does the dimension mean the same as
the shaft diameter. A 1/2" gouge is made from a 1/2" diameter piece of tool
steel.

For all others, the dimensions on tools are in the same category as lumber. The
board is called a 1x4, or designated as 1" lumber, or 4/4, but nowhere will you
find 1".

James Barley

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Jun 17, 2001, 9:33:43 PM6/17/01

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Mmmm, let me see, that would mean that a 5/8 bowl gouge, made by OneWay in
Canada should measure out as 5/8" round stock.
But it is'nt so. Oneways 5/8" gouge is a tad larger then 5/8".
At least several of the ones I'm familiar with are.
Always gonna be one in the crowd...

--
Regards...
James Barley.
http://www.members.home.net/jamesbarley

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Mark Schecter

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Jun 17, 2001, 8:53:47 PM6/17/01

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I was afraid of that. I guess those numbers are supposed to fire my
imagination. Imaginary dimensions? Sheesh. Anyway, thanks for the
illumination, but it's still kinda murky in here.

Mark

ChromeDome

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Jun 18, 2001, 12:24:45 PM6/18/01

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Mark Schecter wrote:
>
> I was afraid of that. I guess those numbers are supposed to fire my
> imagination. Imaginary dimensions? Sheesh. Anyway, thanks for the
> illumination, but it's still kinda murky in here.
>

Don't feel alone. I had the same problem with mortise chisels where the
size is quite critical. I expect a 1/2" mortise chisel (12.4mm, BTW),
to cut a 1/2" mortise, not a 13mm one. Oh well.

Gene

--
Homo Sapiens is a goal, not a description.

Joe Fleming

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Jun 18, 2001, 8:09:19 PM6/18/01

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Mark,

More or less - English bowl gouges are ground from bar stock such
that the indicated gouge size is 1/8" less than the actual bar stock. This
includes Sorby, Crown, Hamlet and Henry Taylor. American made tools call
the gouge the same as the bar stock. This include Glaser, SeriousLathe, etc.
Spindle gouges don't follow this. 1/2" = 1/2" for all products.
So...

bar size English American
bowl gouge bowl gouge
=============================================
3/4" 5/8" 3/4"
5/8" 1/2" 5/8"
1/2" 3/8" 1/2"
3/8" 1/4" 3/8"

Joe - San Diego