I have a copy of Pollards aluminum boat building book, and I have read it.
It looks like he mostly plans on boats to be all cut pieces and welded.
That's great for big boats or even for some small boats, but braking seems
like it would make more sense if you have access to a brake big enough.
Some of the small boat designs (think shallow draft skinny water boats)
would really benefit from a mostly bent hull. Aluminum sheet can be had in
pieces large enough to make most of a hull out of one sheet. Some cutting
and welding is still needed obviously, but if you could brake the keel,
chines, and bottom of the transom only welding the front and the sides in
the back you would have an inherently stronger and more rigid boat for rough
service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how does the
backyard boat builder do it? Are they stuck with all cut and welded pieces,
or hauling their sheet to somebody with a giant brake to do it for them (if
there even is somebody with a brake big enough in the area that hires out)?

On Fri, 30 Dec 2011 12:22:53 -0700, Bob La Londe wrote:

I have a copy of Pollards aluminum boat building book, and I have read
it. It looks like he mostly plans on boats to be all cut pieces and
welded. That's great for big boats or even for some small boats, but
braking seems like it would make more sense if you have access to a
brake big enough. Some of the small boat designs (think shallow draft
skinny water boats) would really benefit from a mostly bent hull.
Aluminum sheet can be had in pieces large enough to make most of a hull
out of one sheet. Some cutting and welding is still needed obviously,
but if you could brake the keel, chines, and bottom of the transom only
welding the front and the sides in the back you would have an inherently
stronger and more rigid boat for rough service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how does
the backyard boat builder do it? Are they stuck with all cut and welded
pieces, or hauling their sheet to somebody with a giant brake to do it
for them (if there even is somebody with a brake big enough in the area
that hires out)?

If you could limit yourself to mostly long skinny pieces, and
particularly if you never "asked" for more than a 90 degree bend or so,
then you could make a brake out of a couple of sections of (big) angle
iron and a bunch of C-clamp-ish thingies.

Make your brake by holding the lower angle open side up, with clamps
distributed along the length to push the upper angle down into it. Put
in your long skinny piece of metal, then run back and forth tightening
clamps (evenly) until you get the bend you want.

It's slow, goofy-looking, and imprecise -- but it's also cheap, easily
made, and should be effective.

If you want to achieve an actual 90 degree bend you'd need to use U-
channel for the lower part, and either augment the upper angle with a rib
along the point (to get a tighter-than-right-angle bend), or just
fabricate your upper angle to have a 60 degree bend or whatever.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

"Tim Wescott" wrote in message
...
On Fri, 30 Dec 2011 12:22:53 -0700, Bob La Londe wrote:

I have a copy of Pollards aluminum boat building book, and I have read
it. It looks like he mostly plans on boats to be all cut pieces and
welded. That's great for big boats or even for some small boats, but
braking seems like it would make more sense if you have access to a
brake big enough. Some of the small boat designs (think shallow draft
skinny water boats) would really benefit from a mostly bent hull.
Aluminum sheet can be had in pieces large enough to make most of a hull
out of one sheet. Some cutting and welding is still needed obviously,
but if you could brake the keel, chines, and bottom of the transom only
welding the front and the sides in the back you would have an inherently
stronger and more rigid boat for rough service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how does
the backyard boat builder do it? Are they stuck with all cut and welded
pieces, or hauling their sheet to somebody with a giant brake to do it
for them (if there even is somebody with a brake big enough in the area
that hires out)?

If you could limit yourself to mostly long skinny pieces, and
particularly if you never "asked" for more than a 90 degree bend or so,
then you could make a brake out of a couple of sections of (big) angle
iron and a bunch of C-clamp-ish thingies.

Make your brake by holding the lower angle open side up, with clamps
distributed along the length to push the upper angle down into it. Put
in your long skinny piece of metal, then run back and forth tightening
clamps (evenly) until you get the bend you want.

It's slow, goofy-looking, and imprecise -- but it's also cheap, easily
made, and should be effective.

If you want to achieve an actual 90 degree bend you'd need to use U-
channel for the lower part, and either augment the upper angle with a rib
along the point (to get a tighter-than-right-angle bend), or just
fabricate your upper angle to have a 60 degree bend or whatever.

I have actually considered some things like that, only I would need C clamps
with a 30 to 40 inch throat. I also considered trying to setup something I
could just drive over with a truck. LOL.

On Fri, 30 Dec 2011 16:14:49 -0700, Bob La Londe wrote:

"Tim Wescott" wrote in message
...
On Fri, 30 Dec 2011 12:22:53 -0700, Bob La Londe wrote:

I have a copy of Pollards aluminum boat building book, and I have read
it. It looks like he mostly plans on boats to be all cut pieces and
welded. That's great for big boats or even for some small boats, but
braking seems like it would make more sense if you have access to a
brake big enough. Some of the small boat designs (think shallow draft
skinny water boats) would really benefit from a mostly bent hull.
Aluminum sheet can be had in pieces large enough to make most of a
hull out of one sheet. Some cutting and welding is still needed
obviously, but if you could brake the keel, chines, and bottom of the
transom only welding the front and the sides in the back you would
have an inherently stronger and more rigid boat for rough service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how
does the backyard boat builder do it? Are they stuck with all cut and
welded pieces, or hauling their sheet to somebody with a giant brake
to do it for them (if there even is somebody with a brake big enough
in the area that hires out)?

If you could limit yourself to mostly long skinny pieces, and
particularly if you never "asked" for more than a 90 degree bend or so,
then you could make a brake out of a couple of sections of (big) angle
iron and a bunch of C-clamp-ish thingies.

Make your brake by holding the lower angle open side up, with clamps
distributed along the length to push the upper angle down into it. Put
in your long skinny piece of metal, then run back and forth tightening
clamps (evenly) until you get the bend you want.

It's slow, goofy-looking, and imprecise -- but it's also cheap, easily
made, and should be effective.

If you want to achieve an actual 90 degree bend you'd need to use U-
channel for the lower part, and either augment the upper angle with a
rib along the point (to get a tighter-than-right-angle bend), or just
fabricate your upper angle to have a 60 degree bend or whatever.

I have actually considered some things like that, only I would need C
clamps with a 30 to 40 inch throat. I also considered trying to setup
something I could just drive over with a truck. LOL.

I was envisioning something that either was restricted to very narrow
pieces, or that required you to fabricate your own clamps.

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com

"Tim Wescott" wrote in message
...
On Fri, 30 Dec 2011 16:14:49 -0700, Bob La Londe wrote:

"Tim Wescott" wrote in message
...
On Fri, 30 Dec 2011 12:22:53 -0700, Bob La Londe wrote:

I have a copy of Pollards aluminum boat building book, and I have read
it. It looks like he mostly plans on boats to be all cut pieces and
welded. That's great for big boats or even for some small boats, but
braking seems like it would make more sense if you have access to a
brake big enough. Some of the small boat designs (think shallow draft
skinny water boats) would really benefit from a mostly bent hull.
Aluminum sheet can be had in pieces large enough to make most of a
hull out of one sheet. Some cutting and welding is still needed
obviously, but if you could brake the keel, chines, and bottom of the
transom only welding the front and the sides in the back you would
have an inherently stronger and more rigid boat for rough service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how
does the backyard boat builder do it? Are they stuck with all cut and
welded pieces, or hauling their sheet to somebody with a giant brake
to do it for them (if there even is somebody with a brake big enough
in the area that hires out)?

If you could limit yourself to mostly long skinny pieces, and
particularly if you never "asked" for more than a 90 degree bend or so,
then you could make a brake out of a couple of sections of (big) angle
iron and a bunch of C-clamp-ish thingies.

Make your brake by holding the lower angle open side up, with clamps
distributed along the length to push the upper angle down into it. Put
in your long skinny piece of metal, then run back and forth tightening
clamps (evenly) until you get the bend you want.

It's slow, goofy-looking, and imprecise -- but it's also cheap, easily
made, and should be effective.

If you want to achieve an actual 90 degree bend you'd need to use U-
channel for the lower part, and either augment the upper angle with a
rib along the point (to get a tighter-than-right-angle bend), or just
fabricate your upper angle to have a 60 degree bend or whatever.

I have actually considered some things like that, only I would need C
clamps with a 30 to 40 inch throat. I also considered trying to setup
something I could just drive over with a truck. LOL.

I was envisioning something that either was restricted to very narrow
pieces, or that required you to fabricate your own clamps.

I know. Think 5' by 12' (or larger) of .063" or .080" None of the brakes
need to 90 or 90+. Some might need to be 80-85.

"Bob La Londe" wrote in message
...
... I know. Think 5' by 12' (or larger) of .063" or .080" None of the
brakes need to 90 or 90+. Some might need to be 80-85.

Can't you draw it up and get quotes?

jsw

On Fri, 30 Dec 2011 16:31:58 -0700, Bob La Londe wrote:
"Tim Wescott" wrote ...
On Fri, 30 Dec 2011 16:14:49 -0700, Bob La Londe wrote:
"Tim Wescott" wrote in ...
On Fri, 30 Dec 2011 12:22:53 -0700, Bob La Londe wrote:
I have a copy of Pollards aluminum boat building book, and I have
read it. It looks like he mostly plans on boats to be all cut pieces
and welded. That's great for big boats or even for some small boats,
but braking seems like it would make more sense if you have
[...]
The problem of course is how do you brake a piece of metal that big?
[...]
Make your brake by holding the lower angle open side up, with clamps
distributed along the length to push the upper angle down into it.
Put in your long skinny piece of metal, then run back and forth
tightening clamps (evenly) until you get the bend you want.

It's slow, goofy-looking, and imprecise -- but it's also cheap,
easily made, and should be effective.

If you want to achieve an actual 90 degree bend you'd need to use U-
channel for the lower part, and either augment the upper angle with a
rib along the point (to get a tighter-than-right-angle bend), or just
fabricate your upper angle to have a 60 degree bend or whatever.

I have actually considered some things like that, only I would need C
clamps with a 30 to 40 inch throat. I also considered trying to setup
something I could just drive over with a truck. LOL.

I was envisioning something that either was restricted to very narrow
pieces, or that required you to fabricate your own clamps.

I know. Think 5' by 12' (or larger) of .063" or .080" None of the
brakes need to 90 or 90+. Some might need to be 80-85.

Suppose you have three 15' lengths of heavy-enough rails (steel
pipe, angle, channel, 4x4 or 6x6 timbers, I-beam, truss, etc) to use
for ways. Mount them with axes parallel, two above rigidly fixed,
one below on the center line (or vice versa). Make a short rolling
carriage with guide wheels and top wheels (eg boat rollers) that work
against the sides and bottom surface of the top ways, and bottom
wheels that will press down against the sheet being bent over the
anvil, the bottom rail. Insert sheet, adjust carriage until tight
(ie producing a small amount of bend in the sheet) and run the
carriage the length of the ways. Adjust tighter, repeat until done.
("Adjust" would either make the carriage thicker, raise top wheels,
lower bottom wheels, lower top ways, or raise the anvil.)

--
jiw

Bob La Londe wrote:
I have a copy of Pollards aluminum boat building book, and I have read it.
It looks like he mostly plans on boats to be all cut pieces and welded.
That's great for big boats or even for some small boats, but braking seems
like it would make more sense if you have access to a brake big enough.
Some of the small boat designs (think shallow draft skinny water boats)
would really benefit from a mostly bent hull. Aluminum sheet can be had in
pieces large enough to make most of a hull out of one sheet. Some cutting
and welding is still needed obviously, but if you could brake the keel,
chines, and bottom of the transom only welding the front and the sides in
the back you would have an inherently stronger and more rigid boat for rough
service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how does the
backyard boat builder do it? Are they stuck with all cut and welded pieces,
or hauling their sheet to somebody with a giant brake to do it for them (if
there even is somebody with a brake big enough in the area that hires out)?




I think the main reason is stress on the hull. The cut and welded seams
will be stronger and take the constant bending better than a simple bent
section of aluminum. Keep in mind that all boats flex small boats flex a
LOT. Aluminum doesn't like flex but with the cut sheets the flex of each
panel can be dissipated better than if you used a single piece. Plus
since many of the pieces come together over
frame sections the cut sheets get welded to the frame and each other in
the same step.


--
Steve W.

"Steve W." wrote in message
...
Bob La Londe wrote:
I have a copy of Pollards aluminum boat building book, and I have read
it.
It looks like he mostly plans on boats to be all cut pieces and welded.
That's great for big boats or even for some small boats, but braking
seems
like it would make more sense if you have access to a brake big enough.
Some of the small boat designs (think shallow draft skinny water boats)
would really benefit from a mostly bent hull. Aluminum sheet can be had
in
pieces large enough to make most of a hull out of one sheet. Some
cutting
and welding is still needed obviously, but if you could brake the keel,
chines, and bottom of the transom only welding the front and the sides in
the back you would have an inherently stronger and more rigid boat for
rough
service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how does
the
backyard boat builder do it? Are they stuck with all cut and welded
pieces,
or hauling their sheet to somebody with a giant brake to do it for them
(if
there even is somebody with a brake big enough in the area that hires
out)?



I think the main reason is stress on the hull. The cut and welded seams
will be stronger and take the constant bending better than a simple bent
section of aluminum. Keep in mind that all boats flex small boats flex a
LOT. Aluminum doesn't like flex but with the cut sheets the flex of each
panel can be dissipated better than if you used a single piece. Plus
since many of the pieces come together over
frame sections the cut sheets get welded to the frame and each other in
the same step.

Commercial boat builders (in some cases using what I would consider the
wrong alloy) make long brakes in aluminum all the time. Most small boats
have rolled or bent ribs in the hull for strength.

"Bob La Londe" wrote in message
...
"Steve W." wrote in
message
...
Bob La Londe wrote:
I have a copy of Pollards aluminum boat
building book, and I have read it.
It looks like he mostly plans on boats to be
all cut pieces and welded.
That's great for big boats or even for some
small boats, but braking seems
like it would make more sense if you have
access to a brake big enough.
Some of the small boat designs (think shallow
draft skinny water boats)
would really benefit from a mostly bent hull.
Aluminum sheet can be had in
pieces large enough to make most of a hull out
of one sheet. Some cutting
and welding is still needed obviously, but if
you could brake the keel,
chines, and bottom of the transom only welding
the front and the sides in
the back you would have an inherently stronger
and more rigid boat for rough
service.

The problem of course is how do you brake a
piece of metal that big?

Yeah I know a giant hydraulic brake would be a
good answer for the
commercial boat builder once they have the
capital for it, but how does the
backyard boat builder do it? Are they stuck
with all cut and welded pieces,
or hauling their sheet to somebody with a
giant brake to do it for them (if
there even is somebody with a brake big enough
in the area that hires out)?



I think the main reason is stress on the hull.
The cut and welded seams will be stronger and
take the constant bending better than a simple
bent section of aluminum. Keep in mind that all
boats flex small boats flex a LOT. Aluminum
doesn't like flex but with the cut sheets the
flex of each panel can be dissipated better
than if you used a single piece. Plus since
many of the pieces come together over
frame sections the cut sheets get welded to the
frame and each other in the same step.

Commercial boat builders (in some cases using
what I would consider the wrong alloy) make long
brakes in aluminum all the time. Most small
boats have rolled or bent ribs in the hull for
strength.


What alloy?

"Phil Kangas" wrote in message
...

"Bob La Londe" wrote in message
...
"Steve W." wrote in message
...
Bob La Londe wrote:
I have a copy of Pollards aluminum boat building book, and I have read
it.
It looks like he mostly plans on boats to be all cut pieces and welded.
That's great for big boats or even for some small boats, but braking
seems
like it would make more sense if you have access to a brake big enough.
Some of the small boat designs (think shallow draft skinny water boats)
would really benefit from a mostly bent hull. Aluminum sheet can be had
in
pieces large enough to make most of a hull out of one sheet. Some
cutting
and welding is still needed obviously, but if you could brake the keel,
chines, and bottom of the transom only welding the front and the sides
in
the back you would have an inherently stronger and more rigid boat for
rough
service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how does
the
backyard boat builder do it? Are they stuck with all cut and welded
pieces,
or hauling their sheet to somebody with a giant brake to do it for them
(if
there even is somebody with a brake big enough in the area that hires
out)?



I think the main reason is stress on the hull. The cut and welded seams
will be stronger and take the constant bending better than a simple bent
section of aluminum. Keep in mind that all boats flex small boats flex a
LOT. Aluminum doesn't like flex but with the cut sheets the flex of each
panel can be dissipated better than if you used a single piece. Plus
since many of the pieces come together over
frame sections the cut sheets get welded to the frame and each other in
the same step.

Commercial boat builders (in some cases using what I would consider the
wrong alloy) make long brakes in aluminum all the time. Most small boats
have rolled or bent ribs in the hull for strength.


What alloy?

5052 seems to be the most popular alloy for hulls, with some builders liking
5086 for structural components, and very much so for larger boats. Some of
the backyard mud boat guys are talking about using 5086 for hulls as well
for its greater strength. I'm not sure its all that much gain in thin hull
material, but...

"Bob La Londe" wrote in message
...
"Phil Kangas" wrote in
message ...

"Bob La Londe" wrote in message
...
"Steve W." wrote in
message
...
Bob La Londe wrote:
I have a copy of Pollards aluminum boat
building book, and I have read it.
It looks like he mostly plans on boats to be
all cut pieces and welded.
That's great for big boats or even for some
small boats, but braking seems
like it would make more sense if you have
access to a brake big enough.
Some of the small boat designs (think
shallow draft skinny water boats)
would really benefit from a mostly bent
hull. Aluminum sheet can be had in
pieces large enough to make most of a hull
out of one sheet. Some cutting
and welding is still needed obviously, but
if you could brake the keel,
chines, and bottom of the transom only
welding the front and the sides in
the back you would have an inherently
stronger and more rigid boat for rough
service.

The problem of course is how do you brake a
piece of metal that big?

Yeah I know a giant hydraulic brake would be
a good answer for the
commercial boat builder once they have the
capital for it, but how does the
backyard boat builder do it? Are they stuck
with all cut and welded pieces,
or hauling their sheet to somebody with a
giant brake to do it for them (if
there even is somebody with a brake big
enough in the area that hires out)?



I think the main reason is stress on the
hull. The cut and welded seams will be
stronger and take the constant bending better
than a simple bent section of aluminum. Keep
in mind that all boats flex small boats flex
a LOT. Aluminum doesn't like flex but with
the cut sheets the flex of each panel can be
dissipated better than if you used a single
piece. Plus since many of the pieces come
together over
frame sections the cut sheets get welded to
the frame and each other in the same step.

Commercial boat builders (in some cases using
what I would consider the wrong alloy) make
long brakes in aluminum all the time. Most
small boats have rolled or bent ribs in the
hull for strength.


What alloy?

5052 seems to be the most popular alloy for
hulls, with some builders liking 5086 for
structural components, and very much so for
larger boats. Some of the backyard mud boat
guys are talking about using 5086 for hulls as
well for its greater strength. I'm not sure its
all that much gain in thin hull material, but...


The 5xxx series are work hardening, the more abuse
the better. A few
years ago I repaired a canoe made in the 50's that
was knicked by a snowplow.
It sure was tough stuff! Almost like stainless, it
was so tough! ;)}

On Fri, 30 Dec 2011 12:22:53 -0700, "Bob La Londe"
wrote:

I have a copy of Pollards aluminum boat building book, and I have read it.
It looks like he mostly plans on boats to be all cut pieces and welded.
That's great for big boats or even for some small boats, but braking seems
like it would make more sense if you have access to a brake big enough.
Some of the small boat designs (think shallow draft skinny water boats)
would really benefit from a mostly bent hull. Aluminum sheet can be had in
pieces large enough to make most of a hull out of one sheet. Some cutting
and welding is still needed obviously, but if you could brake the keel,
chines, and bottom of the transom only welding the front and the sides in
the back you would have an inherently stronger and more rigid boat for rough
service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how does the
backyard boat builder do it? Are they stuck with all cut and welded pieces,
or hauling their sheet to somebody with a giant brake to do it for them (if
there even is somebody with a brake big enough in the area that hires out)?

What kind of boat are you planning to make? A jon boat made of
aluminum typically has lots of longitudinal "stringers" bent into them
with a roll-forming tool, or added-on stringers made of bent aluminum
channels that were then riveted on. We had one of those when I was a
kid.

Small conventional pointed-bow boats traditiionally are formed either
by stretch-forming (used also for canoes) or with big drawing rigs to
pull the sides of the bow together. Then they were TIGed (heliarced,
actually). Today, I understand, they're MIGed.

Without componnd curves, aluminum is too floppy for a boat. When they
draw it into curves, which are simple curves, they generally back it
up with riveted stringers or those rolled-in equivalents.

I watched them stretch-form aluminum boats at the old Fairchild
Aircraft factory in Hagerstown, MD in 1957. My dad had contracted with
them to build boats for Sears after they lost some aircraft contracts.
At the time I didn't know what I was looking at, but after working at
American Machinist for a couple of years, I realized that I had been
watching a stretch-forming operation.

--
Ed Huntress

On Fri, 30 Dec 2011 19:07:57 -0500, Ed Huntress
wrote:

On Fri, 30 Dec 2011 12:22:53 -0700, "Bob La Londe"
wrote:

I have a copy of Pollards aluminum boat building book, and I have read it.
It looks like he mostly plans on boats to be all cut pieces and welded.
That's great for big boats or even for some small boats, but braking seems
like it would make more sense if you have access to a brake big enough.
Some of the small boat designs (think shallow draft skinny water boats)
would really benefit from a mostly bent hull. Aluminum sheet can be had in
pieces large enough to make most of a hull out of one sheet. Some cutting
and welding is still needed obviously, but if you could brake the keel,
chines, and bottom of the transom only welding the front and the sides in
the back you would have an inherently stronger and more rigid boat for rough
service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how does the
backyard boat builder do it? Are they stuck with all cut and welded pieces,
or hauling their sheet to somebody with a giant brake to do it for them (if
there even is somebody with a brake big enough in the area that hires out)?

What kind of boat are you planning to make? A jon boat made of
aluminum typically has lots of longitudinal "stringers" bent into them
with a roll-forming tool, or added-on stringers made of bent aluminum
channels that were then riveted on. We had one of those when I was a
kid.

Small conventional pointed-bow boats traditiionally are formed either
by stretch-forming (used also for canoes) or with big drawing rigs to
pull the sides of the bow together. Then they were TIGed (heliarced,
actually). Today, I understand, they're MIGed.

Without componnd curves, aluminum is too floppy for a boat. When they
draw it into curves, which are simple curves, they generally back it
up with riveted stringers or those rolled-in equivalents.

I watched them stretch-form aluminum boats at the old Fairchild
Aircraft factory in Hagerstown, MD in 1957. My dad had contracted with
them to build boats for Sears after they lost some aircraft contracts.
At the time I didn't know what I was looking at, but after working at
American Machinist for a couple of years, I realized that I had been
watching a stretch-forming operation.

And when you start forming aluminum you have to take active steps to
deal with work fracturing of the metal - and that's Big Factory stuff
you can't do in your garage easily and accurately.

You have to receive the metal annealed Dead Soft, usually frozen on
Dry Ice, stash it away in a big walk-in freezer before you use it, and
that dead-soft state expires in a few weeks even when it stays frozen.
I know that's how they handle aircraft aluminum rivets - you buck them
in place while dead-soft, then the aluminum alloy naturally re-hardens
in a few weeks.

And/Or you have to have a way to re-anneal the aluminum between passes
through the benders and rollers when you are applying severe bends or
multiple operations - that requires a big furnace and a calibrated
control system and convection circulation system to prevent hot spots,
there's not a lot of room between "annealed" and "molten".

Which is why they designed boats from sheet stock and stampings for
"homebuilding" or small shops. You've got to know your limitations.

-- Bruce --

"Bruce L. Bergman (munged human readable)"
wrote in message
You have to receive the metal annealed Dead Soft, usually frozen on
Dry Ice, stash it away in a big walk-in freezer before you use it, and
that dead-soft state expires in a few weeks even when it stays frozen.
I know that's how they handle aircraft aluminum rivets - you buck them
in place while dead-soft, then the aluminum alloy naturally re-hardens
in a few weeks.

And/Or you have to have a way to re-anneal the aluminum between passes
through the benders and rollers when you are applying severe bends or
multiple operations - that requires a big furnace and a calibrated
control system and convection circulation system to prevent hot spots,
there's not a lot of room between "annealed" and "molten".

Which is why they designed boats from sheet stock and stampings for
"homebuilding" or small shops. You've got to know your limitations.

-- Bruce --

That's for 2024. 5052 behaves better.
http://www.wilkinsonsteel.com/aluminum/5052.htm

jsw

On Sat, 31 Dec 2011 09:38:31 -0800, "Bruce L. Bergman (munged human
readable)" wrote:

On Fri, 30 Dec 2011 19:07:57 -0500, Ed Huntress
wrote:

On Fri, 30 Dec 2011 12:22:53 -0700, "Bob La Londe"
wrote:

I have a copy of Pollards aluminum boat building book, and I have read it.
It looks like he mostly plans on boats to be all cut pieces and welded.
That's great for big boats or even for some small boats, but braking seems
like it would make more sense if you have access to a brake big enough.
Some of the small boat designs (think shallow draft skinny water boats)
would really benefit from a mostly bent hull. Aluminum sheet can be had in
pieces large enough to make most of a hull out of one sheet. Some cutting
and welding is still needed obviously, but if you could brake the keel,
chines, and bottom of the transom only welding the front and the sides in
the back you would have an inherently stronger and more rigid boat for rough
service.

The problem of course is how do you brake a piece of metal that big?

Yeah I know a giant hydraulic brake would be a good answer for the
commercial boat builder once they have the capital for it, but how does the
backyard boat builder do it? Are they stuck with all cut and welded pieces,
or hauling their sheet to somebody with a giant brake to do it for them (if
there even is somebody with a brake big enough in the area that hires out)?

What kind of boat are you planning to make? A jon boat made of
aluminum typically has lots of longitudinal "stringers" bent into them
with a roll-forming tool, or added-on stringers made of bent aluminum
channels that were then riveted on. We had one of those when I was a
kid.

Small conventional pointed-bow boats traditiionally are formed either
by stretch-forming (used also for canoes) or with big drawing rigs to
pull the sides of the bow together. Then they were TIGed (heliarced,
actually). Today, I understand, they're MIGed.

Without componnd curves, aluminum is too floppy for a boat. When they
draw it into curves, which are simple curves, they generally back it
up with riveted stringers or those rolled-in equivalents.

I watched them stretch-form aluminum boats at the old Fairchild
Aircraft factory in Hagerstown, MD in 1957. My dad had contracted with
them to build boats for Sears after they lost some aircraft contracts.
At the time I didn't know what I was looking at, but after working at
American Machinist for a couple of years, I realized that I had been
watching a stretch-forming operation.

And when you start forming aluminum you have to take active steps to
deal with work fracturing of the metal - and that's Big Factory stuff
you can't do in your garage easily and accurately.

You have to receive the metal annealed Dead Soft, usually frozen on
Dry Ice, stash it away in a big walk-in freezer before you use it, and
that dead-soft state expires in a few weeks even when it stays frozen.
I know that's how they handle aircraft aluminum rivets - you buck them
in place while dead-soft, then the aluminum alloy naturally re-hardens
in a few weeks.

And/Or you have to have a way to re-anneal the aluminum between passes
through the benders and rollers when you are applying severe bends or
multiple operations - that requires a big furnace and a calibrated
control system and convection circulation system to prevent hot spots,
there's not a lot of room between "annealed" and "molten".

Which is why they designed boats from sheet stock and stampings for
"homebuilding" or small shops. You've got to know your limitations.

-- Bruce --

Well, as Jim says, 5000-Series is less fussy. It doesn't heat-harden,
and, unlike most 2000 and 6000 Series aluminums, it doesn't age harden
after heating. Around here, 5052 is, or used to be, the most-used
material for aluminum boats. Now I see that they're using 5083 in some
applications.

Pollard has developed some techniques for small-scale building of
aluminum boats, but they tend to be full of stringers or frames.
Unless you stretch it into compound curves, it drums and flops around,
without the reinforcement.

I can't think of many places where I'd prefer it to modern wood and
epoxy techniques for a small, one-off boat. But then, I haven't tried.
My experience in working with sheet aluminum for complex shapes has
not been happy. d8-)

--
Ed Huntress

"Ed Huntress" wrote in message
...
...
Pollard has developed some techniques for small-scale building of
aluminum boats, but they tend to be full of stringers or frames.
Unless you stretch it into compound curves, it drums and flops around,
without the reinforcement.

I can't think of many places where I'd prefer it to modern wood and
epoxy techniques for a small, one-off boat. But then, I haven't tried.
My experience in working with sheet aluminum for complex shapes has
not been happy. d8-)
Ed Huntress

It also doesn't take well to external impacts. I wish I had taken videos of
white-water rapids runners jumping in their beached aluminum canoes to pop
out the dents.

jsw

On Dec 31 2011, 11:35*am, "Jim Wilkins" wrote:
"Ed Huntress" wrote in message

...

...
Pollard has developed some techniques for small-scale building of
aluminum boats, but they tend to be full of stringers or frames.
Unless you stretch it into compound curves, it drums and flops around,
without the reinforcement.

I can't think of many places where I'd prefer it to modern wood and
epoxy techniques for a small, one-off boat. But then, I haven't tried.
My experience in working with sheet aluminum for complex shapes has
not been happy. d8-)
Ed Huntress

It also doesn't take well to external impacts. I wish I had taken videos of
white-water rapids runners jumping in their beached aluminum canoes to pop
out the dents.

jsw

Yeah, but a boat with a dent in it will still get you home. A boat
with a hole in it "might" get you home. And aluminum doesn't dry rot,
sun rot, or stress fracture its glue joints sitting on the trailer
even after 50 years. Most of the shallow water jet guys are running
aluminum. The mud boat guys are mostly running aluminum, but there
are still plenty of stitch and glue duck boats out there because its
cheap and easy to build. Its all a trade off on what you want. When
a stitch and glue boats boot starts getting worn from running mud or
jumping beaver dams it is easy to slap a fresh layer of glass and
resin on it. Not as easy with aluminum, but it takes a lot more abuse
to get that way, and you can always mitigate that by painting the
bottom with a good quality air boat hull paint.

For that matter there are some plastic boats out there that will take
an incredible amount of abuse... BUT (note the big but) after a few
years in a UV rich environment like anywhere in the Southwest they
will get hard and brittle. Even if they don't get much use they will
crack at the "hard points."