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Old November 18th 03, 01:24 AM
Kevin
 
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Default steam bending plywood

Does anyone know if it is possible to steam bend 9mm bs1088 Okoume to
an 8 inch radius?

Thanks!

Kevin

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Old November 18th 03, 02:12 PM
Glenn Ashmore
 
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Default steam bending plywood

I do not believe you will get that tight a radius even with major
steaming. A more radical (and dangerous) way that would work at even
tighter radiuses is to soak the wood in anhydrous ammonia. You can do
some pretty amazing stuff with ammonia bending but I would not recommend
it. :-)

Much safer and easier to use 3 pieces of 3 mm and laminate them together
after bending.

Kevin wrote:

Does anyone know if it is possible to steam bend 9mm bs1088 Okoume to
an 8 inch radius?

Thanks!

Kevin


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Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
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Old November 19th 03, 05:45 AM
Kevin
 
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Default steam bending plywood

Ok next question...

how about steam bending 5 mm okoume to a 4 inch radius?

I am debating wether to purchase the 3 mm ply and do three layers as
mentioned in the previous post or to try to bend the 5mm and use two
laminations.

Or should I just look at using "wacky wood" or "flexy ply"?

How strong are the flexible plys if used in a stitch and glue
situation with the outside glassed and epoxied and the inside epoxied?


Thanks,
Kevin


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Old November 19th 03, 11:37 AM
Glenn Ashmore
 
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Default steam bending plywood

Probably worse. The thickness to radius ratio is even lower than 9mm to
8". Okoume is not the best steam bending wood in the world and 5 mm
BS1088 has 5 plys which makes it stiffer. 3mm is only 3 ply which makes
it a good bit more flexable but I am not even sure 3 mm will bend to 4".

When I need to bend under about a 4" radius for fiddle rails and cabinet
edges I steam up some 1/6" veneers and laminate them up from scratch.

When you are getting that tight it is also necessary to use steel
strapping or a well fit caul to keep the outer fibers from splitting.

Kevin wrote:
Ok next question...

how about steam bending 5 mm okoume to a 4 inch radius?

I am debating wether to purchase the 3 mm ply and do three layers as
mentioned in the previous post or to try to bend the 5mm and use two
laminations.

Or should I just look at using "wacky wood" or "flexy ply"?

How strong are the flexible plys if used in a stitch and glue
situation with the outside glassed and epoxied and the inside epoxied?


Thanks,
Kevin


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

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Old November 20th 03, 02:55 PM
Kevin
 
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Default steam bending plywood

I am building a 15" skiff... stitch and glue style. 3/4 merainti
bottom, 9mm okoume sides. I want to do a rounded or fantail transom. I
have scarfed the sides where I am going to attach the transom, and
will scarf the pieces to be bent prior to bending. The bent pieces
will be part of a conic section with a 4" bottom radius and a 12" to
radius. If I remember correctly the my template for the pieces to be
bent is 22" tall and 26" wide at the widest point. The exterior of the
sides are alread coated with 6 oz triaxle glass and the interior with
3 coats of epoxy. I will glues the scarf joint and then glass the
exterior and epoxy the interior of the fantail.

Thanks,
Kevin

Nope, I don't think the 5mm would go either. The three layers of three
MM might go. As far as the other types of wood you mentioned, why
don't you tell us what you are building and what it will be used for,
we might be able to provide more info.
Scotty

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Old November 20th 03, 04:34 PM
William R. Watt
 
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Default steam bending plywood

I don't understand how there can be a 4" radius on a transom only 22" wide.
Could you mean 4" camber? Given the width of the transom and the camber of
the arc you can calcuate the radius of a circular arc. If you look under
"Boats" on my website you'll find a file of various formulae having do to
with circular arcs for boatbuilding, also a BASIC program which calcualtes
radius and points to plot on a circular arc for, say deck beams or cabin
sides. You'll also find a file on dry bending plywood. Sorry, nothing on
steam bending plywood.

I was barely able to get a 2" camber in a 2.5' arched transom by steam
heating lauan underlayment. There's photos of the completed boat,
Dogskiff, on the website. It's not a power boat so its much lighter
construction than your 15' skiff with a 3/4" bottom.

There might be another confusing word below. The angle where things are
attached to a hull is usually called "bevel" as in stem, frame, and
transom bevels. The word "scarf" is used to describe the joining of two
pieces of wood. The angle of the scarf is it's bevel.

Kevin ) writes:
I am building a 15" skiff... stitch and glue style. 3/4 merainti
bottom, 9mm okoume sides. I want to do a rounded or fantail transom. I
have scarfed the sides where I am going to attach the transom, and
will scarf the pieces to be bent prior to bending. The bent pieces
will be part of a conic section with a 4" bottom radius and a 12" to
radius. If I remember correctly the my template for the pieces to be
bent is 22" tall and 26" wide at the widest point. The exterior of the
sides are alread coated with 6 oz triaxle glass and the interior with
3 coats of epoxy. I will glues the scarf joint and then glass the
exterior and epoxy the interior of the fantail.

Thanks,
Kevin

Nope, I don't think the 5mm would go either. The three layers of three
MM might go. As far as the other types of wood you mentioned, why
don't you tell us what you are building and what it will be used for,
we might be able to provide more info.
Scotty



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Old November 20th 03, 04:41 PM
William R. Watt
 
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Default steam bending plywood

William R. Watt ) writes:

I was barely able to get a 2" camber in a 2.5' arched transom by steam
heating lauan underlayment. There's photos of the completed boat,
Dogskiff, on the website. It's not a power boat so its much lighter
construction than your 15' skiff with a 3/4" bottom.


I just remembered that transom is two layers of 1/5" lauan underlayment
laminated with plastic resin glue. Of course that's the same as bending
one layer of 1'5" underlayment. If you look closely at some of the photos
you might be able to see the crease in each layer of lauan underlayment
because it was a bit more than it wanted to bend. The creases don't line
up and the transom is fine but some people are fussy about appearances and
would complain about the creases.

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