Re: [bolger] Freezing inserted parts, was Re: mast welding
At your work the temperature differential between the cold bushings and the
room-temperature steel is sufficient for the purpose, but if it isn't,
heating the steel will make the holes _larger_ as the steel expands. I know
this from experience, not just from common sense, from removing and
installing bearing races, rocker spindles, gudgeon pins and other
paraphernalia in car and motorcycle engines.
room-temperature steel is sufficient for the purpose, but if it isn't,
heating the steel will make the holes _larger_ as the steel expands. I know
this from experience, not just from common sense, from removing and
installing bearing races, rocker spindles, gudgeon pins and other
paraphernalia in car and motorcycle engines.
On Tue, 05 Apr 2005 20:47:22 -0000, Wayne wrote:
> Yes, freezing with dry ice works. Or at least it works for bronze
> bushings in steel plates where I am employed.
>
> The machinist turns the bushings 10 or 20 thousandths over size and
> freezes them overnight in dry ice. Next morning he drops the bushings
> in their holes in ROOM TEMPERATURE steel. By lunchtime they are quite
> snug. Do not heat the larger piece! The hole will expand and the forzen
> piece won't fit OR when the heated piece cools the hole will be too big.
> ...
--
John <jkohnen@...>
http://www.boat-links.com/
I Can't take a well-tanned person seriously. <Cleveland Amory>
You might try Brion Toss' website for advice on this, he has a forum
called Spartalk. Brion answers many of the posts himself, and is
about as knowledgeable as you'll find on the web. The website is at
http://www.briontoss.com/
Jamie Orr
called Spartalk. Brion answers many of the posts himself, and is
about as knowledgeable as you'll find on the web. The website is at
http://www.briontoss.com/
Jamie Orr
--- Inbolger@yahoogroups.com, "fritzdfk" <gaffcat@h...> wrote:
>
> I investigated riveting or using machine screws rather than welding
> and was told it wasn't practicle for that size pipe. There would
> still be an inner sleeve and the fasteners required would weaken
the
> structure too. You would end up chasing your tail, more fasteners
for
> strength but each one you add weakens the joint.
>
> Welding weakens the aluminum by about 50% but that is where the
inner
> sleeve comes in. The weld has full penetration in the outer pipe
and
> penetrates the inner sleeve slightly. You should end up with
> structural integrity roughly equal to a solid piece of pipe.
>
> I think the fit between the outer pipe and the sleeve would have to
> be a very close fit to work. Assembly would involve freezing the
> sleeve and heating the pipe. There is no smaller stock size of pipe
> that is close to fitting inside the outer pipe.
>
> I did fax Bolger a week ago about this and got a hurried reply
saying
> they would get back to me in ten day or so, they are very busy.
There
> were no details for this in the original plan.
>
> I had thought of the light poles before, I'll have to look into
that.
>
> fritz koschmann
Can anybody identify the 'Bolger Leeboard Sharpie'
about 2/3rds the way down the "NEW" page presently
on Duckworks?
My guess is a Cynthia J, modified to have a Cat Yawl rig.
about 2/3rds the way down the "NEW" page presently
on Duckworks?
My guess is a Cynthia J, modified to have a Cat Yawl rig.
--- Inbolger@yahoogroups.com, "Wayne" <wtorry@v...> wrote:
Wayne
In the Swamp.
> If you really want to weld something, weld up a tabernacle for yourthe
> doug-fir spar. Put a doubler plate under the deck and a compression
> post (same doug-fir, we got to get some wood in this boat, eh?) to
> keel and Bob's your uncle! No hole in your watertight deck!Disregard, wrong boat.
Wayne
In the Swamp.
--- Inbolger@yahoogroups.com, "Don Taylor" <nospamforme@c...> wrote:
...(I read somewhere that
> one technique is to use dry ice to chill the sleeve which will reduce
> its diameter, slide it into the mast sections and let it warm up and
> expand. I don't know if this is a for real suggestion.)
> Don.
Yes, freezing with dry ice works. Or at least it works for bronze
bushings in steel plates where I am employed.
The machinist turns the bushings 10 or 20 thousandths over size and
freezes them overnight in dry ice. Next morning he drops the bushings
in their holes in ROOM TEMPERATURE steel. By lunchtime they are quite
snug. Do not heat the larger piece! The hole will expand and the forzen
piece won't fit OR when the heated piece cools the hole will be too big.
If you really want to weld something, weld up a tabernacle for your
doug-fir spar. Put a doubler plate under the deck and a compression
post (same doug-fir, we got to get some wood in this boat, eh?) to the
keel and Bob's your uncle! No hole in your watertight deck!
Wayne
In the Swamp.
Fritz,
Since none of the replies so far seem to have been based on actual,
successful, repairs, please look at the following link:
http://www.caphorn.com/sections/dematage/capsized.htm
It recounts the successful repair of an Alberg 30 mast with a sleeve in the
Chatham Islands. The Alberg 30 went on to complete a successful
circumnavigation.
Paul Esterle
Freelance Boating Writer
Member, Boating Writers International
pages.preferred.com/~pesterle/
www.smallcraftadvisor.com
www.captnpauley.com
Since none of the replies so far seem to have been based on actual,
successful, repairs, please look at the following link:
http://www.caphorn.com/sections/dematage/capsized.htm
It recounts the successful repair of an Alberg 30 mast with a sleeve in the
Chatham Islands. The Alberg 30 went on to complete a successful
circumnavigation.
Paul Esterle
Freelance Boating Writer
Member, Boating Writers International
pages.preferred.com/~pesterle/
www.smallcraftadvisor.com
www.captnpauley.com
Are you sure the pipe you have is even the proper alloy for mast use?
Aluminum is available in a bunch of alloys, all with very specific
uses. A lot of pipe alloys are very soft and bend easily. I am involved
in ham radio, and you wouldn't believe how many antennas you see
mounted at a 30 deg angle because someone found a neat section of
aluminum pipe to use as a mast.
I have had quite a bit of experience fabricating different things from
aluminum, including tubing, and can say without hesitation that you
should absolutely not weld the joint. It will be either brittle and
break or too soft and bend. This will be true even if you weld with a
plug inside. Aluminum has such a low melt point that annealing and
tempering occur at surprisingly low temperatures. Drastic changes can
occur at only a few hundred degrees. Unfortunately, to get a good weld
penetration adn avoid a brittle joint, a pipe as large as this would
need to be preheated into this range to weld. The only answer for
welding is to weld (probably with a sleeve inside unless the pipe is
very thick, and then heat treat. If you can find a flag pole or light
pole manufacturer who can do this cheap, fine. However, sometimes the
best thing is to just buy what you need.
As to the sleeve method, I suspect it will work, but this is an awfully
big pipe to join that way. If you do it, I really think fit is
critical. If the fit is loose at all, the joint will quickly flex/wear
itself away. Using epoxy may work, but you should be sure you
understand the compressive loads on the ends of the plug when the mast
is loaded. They are likely enormous. Think of a 20 foot lever working
with a 6 inch fulcrum apacing. That's why the plug needs to be long.
Also, not flaming, but the idea of splitting the inner tube is bad. It
would rob the plug of a lot of its strength.
I am and engineer by trade and have done a lot of machining in my home
shop, so this is not totally opinion. While a lot of these types of
ideas work on small boats and masts, when your start talking about a 40
footer 8 inches ID, I would get a little nervous trusting my life to
them.
Aluminum is available in a bunch of alloys, all with very specific
uses. A lot of pipe alloys are very soft and bend easily. I am involved
in ham radio, and you wouldn't believe how many antennas you see
mounted at a 30 deg angle because someone found a neat section of
aluminum pipe to use as a mast.
I have had quite a bit of experience fabricating different things from
aluminum, including tubing, and can say without hesitation that you
should absolutely not weld the joint. It will be either brittle and
break or too soft and bend. This will be true even if you weld with a
plug inside. Aluminum has such a low melt point that annealing and
tempering occur at surprisingly low temperatures. Drastic changes can
occur at only a few hundred degrees. Unfortunately, to get a good weld
penetration adn avoid a brittle joint, a pipe as large as this would
need to be preheated into this range to weld. The only answer for
welding is to weld (probably with a sleeve inside unless the pipe is
very thick, and then heat treat. If you can find a flag pole or light
pole manufacturer who can do this cheap, fine. However, sometimes the
best thing is to just buy what you need.
As to the sleeve method, I suspect it will work, but this is an awfully
big pipe to join that way. If you do it, I really think fit is
critical. If the fit is loose at all, the joint will quickly flex/wear
itself away. Using epoxy may work, but you should be sure you
understand the compressive loads on the ends of the plug when the mast
is loaded. They are likely enormous. Think of a 20 foot lever working
with a 6 inch fulcrum apacing. That's why the plug needs to be long.
Also, not flaming, but the idea of splitting the inner tube is bad. It
would rob the plug of a lot of its strength.
I am and engineer by trade and have done a lot of machining in my home
shop, so this is not totally opinion. While a lot of these types of
ideas work on small boats and masts, when your start talking about a 40
footer 8 inches ID, I would get a little nervous trusting my life to
them.
--- Inbolger@yahoogroups.com, "fritzdfk" <gaffcat@h...> wrote:
>
> I need to join two 20' lengths of 8" schedule 40 aluminum pipe to
make
> a 40' mast for Double Eagle. Various people have given me suggestions
> as to how to do this, but I don't think I have gotten the definitive
> answer. With the chinese gaffer rig I need a smooth exterior. Most
> agree that I need an inner sleeve and one engineer type said that an
> inner sleeve 4' long with twice the wall thickness of the outside
pipe
> was needed. As any given pipe may not be perfectly round the sleeve
and
> the interior of the pipe would need to be machined. Does the sleeve
> need to be 4' long? A machine shop has given me a quote for a 2'
sleeve
> at a cost of around $1000 just for machining. Is there another way?
Any
> structural engineers out there?
>
> fritz koschmann
Are you sure the pipe you have is even the proper alloy for mast use?
Aluminum is available in a bunch of alloys, all with very specific
uses. A lot of pipe alloys are very soft and bend easily. I am involved
in ham radio, and you wouldn't believe how many antennas you see
mounted at a 30 deg angle because someone found a neat section of
aluminum pipe to use as a mast.
I have had quite a bit of experience fabricating different things from
aluminum, including tubing, and can say without hesitation that you
should absolutely not weld the joint. It will be either brittle and
break or too soft and bend. This will be true even if you weld with a
plug inside. Aluminum has such a low melt point that annealing and
tempering occur at surprisingly low temperatures. Drastic changes can
occur at only a few hundred degrees. Unfortunately, to get a good weld
penetration adn avoid a brittle joint, a pipe as large as this would
need to be preheated into this range to weld. The only answer for
welding is to weld (probably with a sleeve inside unless the pipe is
very thick, and then heat treat. If you can find a flag pole or light
pole manufacturer who can do this cheap, fine. However, sometimes the
best thing is to just buy what you need.
As to the sleeve method, I suspect it will work, but this is an awfully
big pipe to join that way. If you do it, I really think fit is
critical. If the fit is loose at all, the joint will quickly flex/wear
itself away. Using epoxy may work, but you should be sure you
understand the compressive loads on the ends of the plug when the mast
is loaded. They are likely enormous. Think of a 20 foot lever working
with a 6 inch fulcrum apacing. That's why the plug needs to be long.
Also, not flaming, but the idea of splitting the inner tube is bad. It
would rob the plug of a lot of its strength.
I am and engineer by trade and have done a lot of machining in my home
shop, so this is not totally opinion. While a lot of these types of
ideas work on small boats and masts, when your start talking about a 40
footer 8 inches ID, I would get a little nervous trusting my life to
them.
Aluminum is available in a bunch of alloys, all with very specific
uses. A lot of pipe alloys are very soft and bend easily. I am involved
in ham radio, and you wouldn't believe how many antennas you see
mounted at a 30 deg angle because someone found a neat section of
aluminum pipe to use as a mast.
I have had quite a bit of experience fabricating different things from
aluminum, including tubing, and can say without hesitation that you
should absolutely not weld the joint. It will be either brittle and
break or too soft and bend. This will be true even if you weld with a
plug inside. Aluminum has such a low melt point that annealing and
tempering occur at surprisingly low temperatures. Drastic changes can
occur at only a few hundred degrees. Unfortunately, to get a good weld
penetration adn avoid a brittle joint, a pipe as large as this would
need to be preheated into this range to weld. The only answer for
welding is to weld (probably with a sleeve inside unless the pipe is
very thick, and then heat treat. If you can find a flag pole or light
pole manufacturer who can do this cheap, fine. However, sometimes the
best thing is to just buy what you need.
As to the sleeve method, I suspect it will work, but this is an awfully
big pipe to join that way. If you do it, I really think fit is
critical. If the fit is loose at all, the joint will quickly flex/wear
itself away. Using epoxy may work, but you should be sure you
understand the compressive loads on the ends of the plug when the mast
is loaded. They are likely enormous. Think of a 20 foot lever working
with a 6 inch fulcrum apacing. That's why the plug needs to be long.
Also, not flaming, but the idea of splitting the inner tube is bad. It
would rob the plug of a lot of its strength.
I am and engineer by trade and have done a lot of machining in my home
shop, so this is not totally opinion. While a lot of these types of
ideas work on small boats and masts, when your start talking about a 40
footer 8 inches ID, I would get a little nervous trusting my life to
them.
--- Inbolger@yahoogroups.com, "fritzdfk" <gaffcat@h...> wrote:
>
> I need to join two 20' lengths of 8" schedule 40 aluminum pipe to
make
> a 40' mast for Double Eagle. Various people have given me suggestions
> as to how to do this, but I don't think I have gotten the definitive
> answer. With the chinese gaffer rig I need a smooth exterior. Most
> agree that I need an inner sleeve and one engineer type said that an
> inner sleeve 4' long with twice the wall thickness of the outside
pipe
> was needed. As any given pipe may not be perfectly round the sleeve
and
> the interior of the pipe would need to be machined. Does the sleeve
> need to be 4' long? A machine shop has given me a quote for a 2'
sleeve
> at a cost of around $1000 just for machining. Is there another way?
Any
> structural engineers out there?
>
> fritz koschmann
Just a thought. The homebuilt aircraft people are heavily into welded steel
frames made from steel tubing. The welding techniques for these are well
developed. I seem to remember that when a sleeve is used, a "rose" weld is
used; i.e. a hole is cut in the outer tube and the bead runs around the
perimeter of the hole to join the two pieces.
Just remember that a weld replaces "forged" metal with "cast" metal.
Roger (not qualified to tell you how to do it)
derbyrm@...
http://home.earthlink.net/~derbyrm
frames made from steel tubing. The welding techniques for these are well
developed. I seem to remember that when a sleeve is used, a "rose" weld is
used; i.e. a hole is cut in the outer tube and the bead runs around the
perimeter of the hole to join the two pieces.
Just remember that a weld replaces "forged" metal with "cast" metal.
Roger (not qualified to tell you how to do it)
derbyrm@...
http://home.earthlink.net/~derbyrm
----- Original Message -----
From: "fritzdfk" <gaffcat@...>
>
> I investigated riveting or using machine screws rather than welding
> and was told it wasn't practicle for that size pipe. There would
> still be an inner sleeve and the fasteners required would weaken the
> structure too. You would end up chasing your tail, more fasteners for
> strength but each one you add weakens the joint.
>
> Welding weakens the aluminum by about 50% but that is where the inner
> sleeve comes in. The weld has full penetration in the outer pipe and
> penetrates the inner sleeve slightly. You should end up with
> structural integrity roughly equal to a solid piece of pipe.
>
> I think the fit between the outer pipe and the sleeve would have to
> be a very close fit to work. Assembly would involve freezing the
> sleeve and heating the pipe. There is no smaller stock size of pipe
> that is close to fitting inside the outer pipe.
>
> I did fax Bolger a week ago about this and got a hurried reply saying
> they would get back to me in ten day or so, they are very busy. There
> were no details for this in the original plan.
>
> I had thought of the light poles before, I'll have to look into that.
Hi Fritz;
Peter's idea of using a wooden plug is a good one, as are his comments
about using steel pipe instead of aluminum. My choice would have been
the steel.
If you insist on welding then you should use plug welds, not a fillet.
There was quite a bit of discussion about joining masts on the
multihullboatbuilder list a few years ago. Most recommended bedding
the sleeve with epoxy. I would add to this the need to use a low
modulus (soft) epoxy to account for flex.
$1000 for machining is a lot of money for two hours work. I have
contacts near Boeing in Seattle that might be able to find a scrap
from Boeing surplus. They could probably send you a finished part for
much less.
I still think Peter's idea of using a wooden plug is best.
Doug
Peter's idea of using a wooden plug is a good one, as are his comments
about using steel pipe instead of aluminum. My choice would have been
the steel.
If you insist on welding then you should use plug welds, not a fillet.
There was quite a bit of discussion about joining masts on the
multihullboatbuilder list a few years ago. Most recommended bedding
the sleeve with epoxy. I would add to this the need to use a low
modulus (soft) epoxy to account for flex.
$1000 for machining is a lot of money for two hours work. I have
contacts near Boeing in Seattle that might be able to find a scrap
from Boeing surplus. They could probably send you a finished part for
much less.
I still think Peter's idea of using a wooden plug is best.
Doug
Also, if I remember right, pipe is measured by the inside diameter and
tubing is measured by outside diameter. It may be the other way around as
well but the idea is that one will slide into the other with some minor
heating of the outside tube and freezing the sleeve.
You might want to check out if I remember right and if so, it'll be fairly
easy to insert the sleeve. I'd use machine screws to hold it all together.
Jeff
-----Original Message-----
From: Paul W. Esterle [mailto:pesterle@...]
Sent: Monday, April 04, 2005 8:46 PM
To:bolger@yahoogroups.com
Subject: Re: [bolger] mast welding
Fritz,
Sleeves have been used quite a bit for assembling masts or repairing broken
masts. None that I have ever seen have been machined. I would use a 4'
section of the same pipe you are using for the mast. Cut a slit in the side
of the sleeve wide enough so that it can be forced inside the mast tube, it
should be a tight fit but doable. Drive it in half way and then anchor it.
It can be riveted, epoxied or use machine screws. The second section is then
driven onto the sleeve. You might want to check with a mast shop for some
general hints, also.
Paul Esterle
Freelance Boating Writer
Member, Boating Writers International
pages.preferred.com/~pesterle/
www.smallcraftadvisor.com
www.captnpauley.com
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tubing is measured by outside diameter. It may be the other way around as
well but the idea is that one will slide into the other with some minor
heating of the outside tube and freezing the sleeve.
You might want to check out if I remember right and if so, it'll be fairly
easy to insert the sleeve. I'd use machine screws to hold it all together.
Jeff
-----Original Message-----
From: Paul W. Esterle [mailto:pesterle@...]
Sent: Monday, April 04, 2005 8:46 PM
To:bolger@yahoogroups.com
Subject: Re: [bolger] mast welding
Fritz,
Sleeves have been used quite a bit for assembling masts or repairing broken
masts. None that I have ever seen have been machined. I would use a 4'
section of the same pipe you are using for the mast. Cut a slit in the side
of the sleeve wide enough so that it can be forced inside the mast tube, it
should be a tight fit but doable. Drive it in half way and then anchor it.
It can be riveted, epoxied or use machine screws. The second section is then
driven onto the sleeve. You might want to check with a mast shop for some
general hints, also.
Paul Esterle
Freelance Boating Writer
Member, Boating Writers International
pages.preferred.com/~pesterle/
www.smallcraftadvisor.com
www.captnpauley.com
------------------------ Yahoo! Groups Sponsor --------------------~--> Give
the gift of life to a sick child.
Support St. Jude Children's Research Hospital's 'Thanks & Giving.'
http://us.click.yahoo.com/5iY7fA/6WnJAA/Y3ZIAA/_0TolB/TM
--------------------------------------------------------------------~->
Bolger rules!!!
- no cursing, flaming, trolling, spamming, or flogging dead horses
- stay on topic, stay on thread, punctuate, no 'Ed, thanks, Fred' posts
- Pls add your comments at the TOP, SIGN your posts, and snip away
- Plans: Mr. Philip C. Bolger, P.O. Box 1209, Gloucester, MA, 01930, Fax:
(978) 282-1349
- Unsubscribe:bolger-unsubscribe@yahoogroups.com
- Open discussion:bolger_coffee_lounge-subscribe@yahoogroups.com
Yahoo! Groups Links
--- Inbolger@yahoogroups.com, "fritzdfk" <gaffcat@h...> wrote:
As you know,I'm about as qualified to answer your question as I
am to fly the space shuttle but in the interest of keeping this alive
here I go with my"thoughts",
option 1) sell your 2 lengths of 20 foot pipe and buy 1 40 foot length.
option 2) since this mast is a free standing affair and can be
expected to flex somewhat,how about inserting a nice big wooden plug
to keep the two halves together.The plug could be built up of
laminated 2X10's and inserted with the laminations oriented
athwartship to give some resistance to mast bend.With the wooden plug
presumeably less hard then the aluminium, it would avoid creating
a "hard spot" such as a metal sleave would perhaps create half way up
the mast.
option3) Double Eagle will have a tremendous amount of static
stability so why even bother going with aluminium pipe.Straight away
steel pipe or even a solid tree(a la George Beuhler) would appear to
be easily doable work arounds for your present
situation.Besides,aren't trees kind-o-abundant up in your neck of the
woods? :-)
Sincerely,
Peter,shedding thousands of brain cells per minute,Lenihan..........
>make
> I need to join two 20' lengths of 8" schedule 40 aluminum pipe to
> a 40' mast for Double Eagle.Hi Fritz,
As you know,I'm about as qualified to answer your question as I
am to fly the space shuttle but in the interest of keeping this alive
here I go with my"thoughts",
option 1) sell your 2 lengths of 20 foot pipe and buy 1 40 foot length.
option 2) since this mast is a free standing affair and can be
expected to flex somewhat,how about inserting a nice big wooden plug
to keep the two halves together.The plug could be built up of
laminated 2X10's and inserted with the laminations oriented
athwartship to give some resistance to mast bend.With the wooden plug
presumeably less hard then the aluminium, it would avoid creating
a "hard spot" such as a metal sleave would perhaps create half way up
the mast.
option3) Double Eagle will have a tremendous amount of static
stability so why even bother going with aluminium pipe.Straight away
steel pipe or even a solid tree(a la George Beuhler) would appear to
be easily doable work arounds for your present
situation.Besides,aren't trees kind-o-abundant up in your neck of the
woods? :-)
Sincerely,
Peter,shedding thousands of brain cells per minute,Lenihan..........
fritzdfk wrote:
there to hold the mast together, but to stop the sleeve from slipping
down the mast. The less fasteners the better really. Some epoxy or
other goo between the tubes will help too. Also consider a bevel at
the ends of the sleeve to avoid a hard spot.
Laser masts are made in two pieces. The upper piece slips inside the
lower piece, with a collar between them. Very old models (like mine) had
two rivets holding the collar in place. Over time, as the mast flexed,
the rivets would work and weaken the mast. My laser mast broke just
above the join as a result. Current models have a single rivet, and
I believe best practice calls for placing the rivet at the rear of
the mast where it will be in compression, rather than at the front
or sides where it will tear the aluminium.
Of course, a laser mast is orders of magnitude smaller than your
project, but it is food for thought.
Bruce Fountain
Systems Engineer
Union Switch & Signal
Perth, Western Australia
> I investigated riveting or using machine screws rather than weldingI suspect that you wouldn't need many fasteners. The screws aren't
> and was told it wasn't practicle for that size pipe. There would
> still be an inner sleeve and the fasteners required would weaken the
> structure too. You would end up chasing your tail, more fasteners for
> strength but each one you add weakens the joint.
there to hold the mast together, but to stop the sleeve from slipping
down the mast. The less fasteners the better really. Some epoxy or
other goo between the tubes will help too. Also consider a bevel at
the ends of the sleeve to avoid a hard spot.
Laser masts are made in two pieces. The upper piece slips inside the
lower piece, with a collar between them. Very old models (like mine) had
two rivets holding the collar in place. Over time, as the mast flexed,
the rivets would work and weaken the mast. My laser mast broke just
above the join as a result. Current models have a single rivet, and
I believe best practice calls for placing the rivet at the rear of
the mast where it will be in compression, rather than at the front
or sides where it will tear the aluminium.
Of course, a laser mast is orders of magnitude smaller than your
project, but it is food for thought.
Bruce Fountain
Systems Engineer
Union Switch & Signal
Perth, Western Australia
I investigated riveting or using machine screws rather than welding
and was told it wasn't practicle for that size pipe. There would
still be an inner sleeve and the fasteners required would weaken the
structure too. You would end up chasing your tail, more fasteners for
strength but each one you add weakens the joint.
Welding weakens the aluminum by about 50% but that is where the inner
sleeve comes in. The weld has full penetration in the outer pipe and
penetrates the inner sleeve slightly. You should end up with
structural integrity roughly equal to a solid piece of pipe.
I think the fit between the outer pipe and the sleeve would have to
be a very close fit to work. Assembly would involve freezing the
sleeve and heating the pipe. There is no smaller stock size of pipe
that is close to fitting inside the outer pipe.
I did fax Bolger a week ago about this and got a hurried reply saying
they would get back to me in ten day or so, they are very busy. There
were no details for this in the original plan.
I had thought of the light poles before, I'll have to look into that.
fritz koschmann
and was told it wasn't practicle for that size pipe. There would
still be an inner sleeve and the fasteners required would weaken the
structure too. You would end up chasing your tail, more fasteners for
strength but each one you add weakens the joint.
Welding weakens the aluminum by about 50% but that is where the inner
sleeve comes in. The weld has full penetration in the outer pipe and
penetrates the inner sleeve slightly. You should end up with
structural integrity roughly equal to a solid piece of pipe.
I think the fit between the outer pipe and the sleeve would have to
be a very close fit to work. Assembly would involve freezing the
sleeve and heating the pipe. There is no smaller stock size of pipe
that is close to fitting inside the outer pipe.
I did fax Bolger a week ago about this and got a hurried reply saying
they would get back to me in ten day or so, they are very busy. There
were no details for this in the original plan.
I had thought of the light poles before, I'll have to look into that.
fritz koschmann
Fritz,
Sleeves have been used quite a bit for assembling masts or repairing broken
masts. None that I have ever seen have been machined. I would use a 4'
section of the same pipe you are using for the mast. Cut a slit in the side
of the sleeve wide enough so that it can be forced inside the mast tube, it
should be a tight fit but doable. Drive it in half way and then anchor it.
It can be riveted, epoxied or use machine screws. The second section is then
driven onto the sleeve. You might want to check with a mast shop for some
general hints, also.
Paul Esterle
Freelance Boating Writer
Member, Boating Writers International
pages.preferred.com/~pesterle/
www.smallcraftadvisor.com
www.captnpauley.com
Sleeves have been used quite a bit for assembling masts or repairing broken
masts. None that I have ever seen have been machined. I would use a 4'
section of the same pipe you are using for the mast. Cut a slit in the side
of the sleeve wide enough so that it can be forced inside the mast tube, it
should be a tight fit but doable. Drive it in half way and then anchor it.
It can be riveted, epoxied or use machine screws. The second section is then
driven onto the sleeve. You might want to check with a mast shop for some
general hints, also.
Paul Esterle
Freelance Boating Writer
Member, Boating Writers International
pages.preferred.com/~pesterle/
www.smallcraftadvisor.com
www.captnpauley.com
> With the chinese gaffer rig I need a smooth exterior.Smooth, yeah, but not mirror like. [Check with Bolger],
but I suspect that defects of 1/8" [or even 1/4"] would be OK,
especially if the sharp edges were ground smooth.
What does the desinger say?
Phil Smith
--- fritzdfk <gaffcat@...> wrote:
Phil Smith
--- fritzdfk <gaffcat@...> wrote:
>http://us.click.yahoo.com/6iY7fA/5WnJAA/Y3ZIAA/_0TolB/TM
>
> I need to join two 20' lengths of 8" schedule 40
> aluminum pipe to make
> a 40' mast for Double Eagle. Various people have
> given me suggestions
> as to how to do this, but I don't think I have
> gotten the definitive
> answer. With the chinese gaffer rig I need a smooth
> exterior. Most
> agree that I need an inner sleeve and one engineer
> type said that an
> inner sleeve 4' long with twice the wall thickness
> of the outside pipe
> was needed. As any given pipe may not be perfectly
> round the sleeve and
> the interior of the pipe would need to be machined.
> Does the sleeve
> need to be 4' long? A machine shop has given me a
> quote for a 2' sleeve
> at a cost of around $1000 just for machining. Is
> there another way? Any
> structural engineers out there?
>
> fritz koschmann
>
>
>
>
>
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--- Inbolger@yahoogroups.com, "fritzdfk" <gaffcat@h...> wrote:
First of all do not weld your mast sections because you will destroy
the temper of the aluminium.
I have a mast that was made out of two pipes joined with an inner
sleeve. The main sections are fastened to the sleeve using machine
screws. I doubt that the sleeve and the main sections were machined.
The builder may have used epoxy.. I believe that the sleeve is simply
the next pipe or tube size down that will fit. (I read somewhere that
one technique is to use dry ice to chill the sleeve which will reduce
its diameter, slide it into the mast sections and let it warm up and
expand. I don't know if this is a for real suggestion.)
If you have not already bought your pipes then you might want to
investigate having a lamp pole manufacturer make your mast for you. A
friend had a 40+' Freedom style mast made this way. They use a
spin-tapering machine and a gigantic oven to restore the temper after
the tapering is done. I don't know the price, but it was not horrific.
BTW. He had to replace his mast because his old mast cracked at the
joint where two sections had been welded together.
Don.
>I am not a structural engineer, but...
> I need to join two 20' lengths of 8" schedule 40 aluminum pipe to make
> a 40' mast for Double Eagle. Various people have given me suggestions
> as to how to do this, but I don't think I have gotten the definitive
> answer. With the chinese gaffer rig I need a smooth exterior. Most
> agree that I need an inner sleeve and one engineer type said that an
> inner sleeve 4' long with twice the wall thickness of the outside pipe
> was needed. As any given pipe may not be perfectly round the sleeve and
> the interior of the pipe would need to be machined. Does the sleeve
> need to be 4' long? A machine shop has given me a quote for a 2' sleeve
> at a cost of around $1000 just for machining. Is there another way? Any
> structural engineers out there?
First of all do not weld your mast sections because you will destroy
the temper of the aluminium.
I have a mast that was made out of two pipes joined with an inner
sleeve. The main sections are fastened to the sleeve using machine
screws. I doubt that the sleeve and the main sections were machined.
The builder may have used epoxy.. I believe that the sleeve is simply
the next pipe or tube size down that will fit. (I read somewhere that
one technique is to use dry ice to chill the sleeve which will reduce
its diameter, slide it into the mast sections and let it warm up and
expand. I don't know if this is a for real suggestion.)
If you have not already bought your pipes then you might want to
investigate having a lamp pole manufacturer make your mast for you. A
friend had a 40+' Freedom style mast made this way. They use a
spin-tapering machine and a gigantic oven to restore the temper after
the tapering is done. I don't know the price, but it was not horrific.
BTW. He had to replace his mast because his old mast cracked at the
joint where two sections had been welded together.
Don.
I need to join two 20' lengths of 8" schedule 40 aluminum pipe to make
a 40' mast for Double Eagle. Various people have given me suggestions
as to how to do this, but I don't think I have gotten the definitive
answer. With the chinese gaffer rig I need a smooth exterior. Most
agree that I need an inner sleeve and one engineer type said that an
inner sleeve 4' long with twice the wall thickness of the outside pipe
was needed. As any given pipe may not be perfectly round the sleeve and
the interior of the pipe would need to be machined. Does the sleeve
need to be 4' long? A machine shop has given me a quote for a 2' sleeve
at a cost of around $1000 just for machining. Is there another way? Any
structural engineers out there?
fritz koschmann
a 40' mast for Double Eagle. Various people have given me suggestions
as to how to do this, but I don't think I have gotten the definitive
answer. With the chinese gaffer rig I need a smooth exterior. Most
agree that I need an inner sleeve and one engineer type said that an
inner sleeve 4' long with twice the wall thickness of the outside pipe
was needed. As any given pipe may not be perfectly round the sleeve and
the interior of the pipe would need to be machined. Does the sleeve
need to be 4' long? A machine shop has given me a quote for a 2' sleeve
at a cost of around $1000 just for machining. Is there another way? Any
structural engineers out there?
fritz koschmann