Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??

wrote in message
oups.com...
Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??


Laminate. Thin, dry sections. Wood that's green, or air dry is always a
better bet for steaming than something that's been through the kiln.

wrote:
Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??


My understanding, is that steam bending works best on *green* wood.

You might have better luck doing bend lamination with matching scarf
joints to build up the desired thickness. Issue here would be that the
circumference would change upon each lamination application, so you'd
have to cut laminations longer than needed and test fit them to get the
appropriate lengths.

~Mark.

wrote in message
oups.com...
Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a
0.381m(15")
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??


As others have suggested, I too would use a bent lamination technique to
make the porthole liners. If for no other reason, they will be very stable
in a barge environment.

Basic bent lamination technique:
Slice the wood into thin strips 1/16" -1/8" (1.5mm-3mm)
Glue and wrap the strips around a form, (use a slow setting glue)
Clamp in place.
Unclamp and machine to finished size, sand and apply finish.

Dave



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wrote in message
oups.com...
Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??

Steaming is a big and technical subject. Curved work in general and
boatbuilding are even vaster, so nobody will be able to tell you how to do
this or even run through the options in a quick ng reply.

Mahogany is not a wood for steam bending. Bending requires a strait grain
and mahog has too much cross grain. Further to that i do not know how you
would intend to make a complete ring of timber. Are you steaming pieces and
then scarfing them together? If you laminate you might be advised to buy
structural veneers rather than trying to cut them.

Tim w

wrote in message
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

After attending a recent seminar at Lee Valley Tools conducted by Michael
Fortune and watching him bend wood, I'm convinced almost any radius within
reason can be obtained. I'm not that sure Mahogany is the best wood since
straight grained wood is the best for steam bending, but you should be able
to find something suitable. My first suggestion is that you read up a bit on
bending wood.
http://www.leevalley.com/wood/page.a...=1,45866,45867

There's also another route you might consider for these portholes. Bendable
Lauan also known as Bendable Plywood or "Wiggle Board", (information also
courtesy of Mr. Fortune) might meet your needs. You could laminate several
layers together to obtain your desired thickness. I've provided one sample
picture of it in the link below. It does come in longer lengths (at least
96") than listed on the website.

http://www.vandykes.com/product/02007822/

I'm guessing that mahogany veneer would need to be 1/16" at most to agree
to an 8" radius. Experimentation is needed.
As an alternative, turn the veneer such that the bend is cross-grain and
laminate. A couple of laminations of light glass cloth can supply
cross-grain strength.
Vacuum bagging would be a big wrote in message
oups.com...
Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??

wrote:
Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??

Try this: http://www.wcha.org/tidbits/steamfaq.html

On 9 Jun 2006 12:18:42 -0700, wrote:

Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??


Yes it is possible to steam mahogany to this radius. Steaming is
somewhat of an art. After bending wood there might be compression
failure or other defects. Use straight grain wood, free from knots
or other defects. Green wood bends much easier than dried wood, so if
you can get some green (not dried) mahogany you're good to go. Making
the form and strap is probably the most time consuming part. You want
the form made such that your clamps hook into it quickly/easily. Steam
the strips for about 1 hour, use thick leather gloves, BBQ tongs, and
have everything carefully setup in advance. Planning is very
important. After removing the steamed strips you have a very short
time (30 seconds or so) to get them into the form. Make sure you will
have enough water and heat to last 1 hour. If there is any
interruption in the heat/steam your wood will probably be ruined.
Woods that are particularly good for bending are as follows:

ash, elm, beech, birch, hickory, oak, and walnut

I'd probably use 1/8" thick strips. After curing in the form, then
laminate (glue) them together. Your liners will be very strong.

Warning: It is very easy to get steam burns--be careful!

wrote:
Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??


Mahogany is not a good wood to bend. It's almost impossible to steam
bend anything close to that radius. The rig you would have to make would
be dangerous. According to my Fine Woodworking Bending Wood book the
best radius you would see for 1" thick mahogany is 32" to 36".

Even bent laminations are tricky with mahogany. If you want to attemp
this keep the strips really thin 3/32" to 1/16". Cut lots of extras,
you'll need them. Bend SLOWLY. Have both an inside and outside form. My
guess is 1/2 to 3/4 of them will break. Use epoxy if you do this. I
prefer a nice slow setting gel type.

The other choice is cutting a circle. This would be the most wasteful,
but might be your best bet.

The advantage to bending wood over cutting curved forms is tensile
strength. Grain orientation (and therefor tensile strength) is
inconsistent on a curved cut form, where a bent form will have fairly
consistent grain orientation. IMO A pothole liner would not need need
the tensile strength a bent piece of wood would give. It would be
supported on all sides, unless I'm missing something.


The other best bet option. Choose a contrasting wood that does bend well
like Ash, White Oak, or Red Oak. Walnut and Cherry will also bend well.


Christian

Christian Brink wrote:

wrote:
Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??


Mahogany is not a good wood to bend. It's almost impossible to steam
bend anything close to that radius. The rig you would have to make would
be dangerous. According to my Fine Woodworking Bending Wood book the
best radius you would see for 1" thick mahogany is 32" to 36".

Even bent laminations are tricky with mahogany. If you want to attemp
this keep the strips really thin 3/32" to 1/16". Cut lots of extras,
you'll need them. Bend SLOWLY. Have both an inside and outside form. My
guess is 1/2 to 3/4 of them will break. Use epoxy if you do this. I
prefer a nice slow setting gel type.

The other choice is cutting a circle. This would be the most wasteful,
but might be your best bet.

The advantage to bending wood over cutting curved forms is tensile
strength. Grain orientation (and therefor tensile strength) is
inconsistent on a curved cut form, where a bent form will have fairly
consistent grain orientation. IMO A pothole liner would not need need
the tensile strength a bent piece of wood would give. It would be
supported on all sides, unless I'm missing something.


The other best bet option. Choose a contrasting wood that does bend well
like Ash, White Oak, or Red Oak. Walnut and Cherry will also bend well.

I'd avoid ash or red oak on a boat--you can pretty much count on everything
being wet even on a barge so decay resistance is an issue--white oak or
walnut would be much better bets IMO. Cherry I'm not sure about, I'd have
to look up the decay resistance figures.

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

J. Clarke wrote:


I'd avoid ash or red oak on a boat--you can pretty much count on everything
being wet even on a barge so decay resistance is an issue--white oak or
walnut would be much better bets IMO. Cherry I'm not sure about, I'd have
to look up the decay resistance figures.


I do use Ask and Red Oak for bent lam fishing nets (which I try to keep
in the water as often as I can ), I have never had a problem, if they
have been finished properly. I assume these are going to be above water
line.

Christian

You might consider some variant of a mast hoop. See
http://www-personal.umich.edu/~mrwiz...es/hoops01.pdf

In my very limited experience with laminating curved wooden pieces, I found
that if you pulled the wood around the form, it would probably break. If
you kept the piece in compression, it probably wouldn't. Push it into/onto
the form.

Roger

http://home.insightbb.com/~derbyrm

"J. Clarke" wrote in message
...
Christian Brink wrote:

wrote:
Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??


Mahogany is not a good wood to bend. It's almost impossible to steam
bend anything close to that radius. The rig you would have to make would
be dangerous. According to my Fine Woodworking Bending Wood book the
best radius you would see for 1" thick mahogany is 32" to 36".

Even bent laminations are tricky with mahogany. If you want to attemp
this keep the strips really thin 3/32" to 1/16". Cut lots of extras,
you'll need them. Bend SLOWLY. Have both an inside and outside form. My
guess is 1/2 to 3/4 of them will break. Use epoxy if you do this. I
prefer a nice slow setting gel type.

The other choice is cutting a circle. This would be the most wasteful,
but might be your best bet.

The advantage to bending wood over cutting curved forms is tensile
strength. Grain orientation (and therefor tensile strength) is
inconsistent on a curved cut form, where a bent form will have fairly
consistent grain orientation. IMO A pothole liner would not need need
the tensile strength a bent piece of wood would give. It would be
supported on all sides, unless I'm missing something.


The other best bet option. Choose a contrasting wood that does bend well
like Ash, White Oak, or Red Oak. Walnut and Cherry will also bend well.

I'd avoid ash or red oak on a boat--you can pretty much count on
everything
being wet even on a barge so decay resistance is an issue--white oak or
walnut would be much better bets IMO. Cherry I'm not sure about, I'd have
to look up the decay resistance figures.

--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)

On 9 Jun 2006 12:18:42 -0700, wrote:

Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??


Barge....mahogany?

Anyway, I'd go with Marine grade plywood. It is hard to find the stuff
below 1/4" but if the bend is too much you can make multiple scores on
the back side with a C-Saw set to a bit less than an 1/8".
You can find it in mahogany veneer as well.

J

On 9 Jun 2006 12:18:42 -0700, wrote:

Hi,
I need to make some porthole liners for a barge and I was thinking of
steaming some wood strips. Size is approx 1.15m long - it is a 0.381m
diameter porthole - 60mm wide and 6 - 8 mm thick. I was thinking of
using mahogany or similar dark hard wood.

Can I bend steamed mahogany to this radius?? - or any other
suggestions??

Might be possible to soften laminations in a dishwasher (!)

Also 'pre bend' them on a former, so once dried they can be glued with
minimal further bending.

Also... make them over long then cut through both layers with a
slightly extended snap-off knife to get a decent butt joint on each.

cheers,
Pete.