Creating a swaged hole in the bottom of a fuel tank.

Dear All,

I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge weld
the six fittings specified in the plans. Four of the fittings are finger
strainers and one is for the sight gauge. There is one more hole on the top
for the filler. As there are only six holes in three different diameters, I
was thinking about doing it using simple hand techniques rather than
expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the holes
over 3/8" steel plate with holes .180 oversize, then use a polyethelene
bossing hammer to swage the edge of the hole into the female die hole. The
holes in the female die would have the edges relieved to accomodate a bend
radius. It might be time consuming but educational.

Any advice or previous experience to share

--
John "Ebby" Ebensperger
Hatz Classic s/n37
Camden, NY

Ebby wrote:
Dear All,

I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge weld
the six fittings specified in the plans. Four of the fittings are finger
strainers and one is for the sight gauge. There is one more hole on the top
for the filler. As there are only six holes in three different diameters, I
was thinking about doing it using simple hand techniques rather than
expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the holes
over 3/8" steel plate with holes .180 oversize, then use a polyethelene
bossing hammer to swage the edge of the hole into the female die hole. The
holes in the female die would have the edges relieved to accomodate a bend
radius. It might be time consuming but educational.

Any advice or previous experience to share


A piece of 1/2" plywood and a couple chunks of 2x4. Tack plywood to one
of the blocks and use a small hole saw with a 1/4" centering bit to cut
the inside diameter of the swage. The piece that you dig from the hole
saw goes on one side of the aluminum. Use a bigger hole saw, centering
on the same 1/4" hole, cut the outside diameter of the swage, then drill
the 1/4" hole all the way through the block. Drill a 1/4" hole through
the other block. Drill a 1/4" hole where the swage will go.

Thread a sufficiently long bolt through a fender washer, the block with
the plywood attached, the aluminum, the piece you dug out of the small
hole saw, the other 2x4 block, then another fender washer. Spin a nut
down to extrude the swage.

I don't know if this will work on .090, but I've used this technique on
thinner material.

How big is this tank that you are using 90 thou?


"Ernest Christley" wrote in message
...
Ebby wrote:
Dear All,

I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge
weld the six fittings specified in the plans. Four of the fittings are
finger strainers and one is for the sight gauge. There is one more hole
on the top for the filler. As there are only six holes in three
different diameters, I was thinking about doing it using simple hand
techniques rather than expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the
holes over 3/8" steel plate with holes .180 oversize, then use a
polyethelene bossing hammer to swage the edge of the hole into the female
die hole. The holes in the female die would have the edges relieved to
accomodate a bend radius. It might be time consuming but educational.

Any advice or previous experience to share


A piece of 1/2" plywood and a couple chunks of 2x4. Tack plywood to one
of the blocks and use a small hole saw with a 1/4" centering bit to cut
the inside diameter of the swage. The piece that you dig from the hole
saw goes on one side of the aluminum. Use a bigger hole saw, centering on
the same 1/4" hole, cut the outside diameter of the swage, then drill the
1/4" hole all the way through the block. Drill a 1/4" hole through the
other block. Drill a 1/4" hole where the swage will go.

Thread a sufficiently long bolt through a fender washer, the block with
the plywood attached, the aluminum, the piece you dug out of the small
hole saw, the other 2x4 block, then another fender washer. Spin a nut down
to extrude the swage.

I don't know if this will work on .090, but I've used this technique on
thinner material.

Cy,

This tank is for a Hatz Classic biplane. The capacity approaches 22
gallons. The upper surface of the tank is screwed down to the top of the
forward and aft spars of the center section with a series of (11 on each
edge) 10-32 truss head screws. The tank measures 54" long and 28 5/8" wide.
The actual tank nests in between the forward and aft spars. The .090" is
specified in the plans.

Ebby


"Cy Galley" wrote in message
news:IMkUg.178242$FQ1.121119@attbi_s71...
How big is this tank that you are using 90 thou?


"Ernest Christley" wrote in message
...
Ebby wrote:
Dear All,

I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge
weld the six fittings specified in the plans. Four of the fittings are
finger strainers and one is for the sight gauge. There is one more hole
on the top for the filler. As there are only six holes in three
different diameters, I was thinking about doing it using simple hand
techniques rather than expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the
holes over 3/8" steel plate with holes .180 oversize, then use a
polyethelene bossing hammer to swage the edge of the hole into the
female die hole. The holes in the female die would have the edges
relieved to accomodate a bend radius. It might be time consuming but
educational.

Any advice or previous experience to share


A piece of 1/2" plywood and a couple chunks of 2x4. Tack plywood to one
of the blocks and use a small hole saw with a 1/4" centering bit to cut
the inside diameter of the swage. The piece that you dig from the hole
saw goes on one side of the aluminum. Use a bigger hole saw, centering
on the same 1/4" hole, cut the outside diameter of the swage, then drill
the 1/4" hole all the way through the block. Drill a 1/4" hole through
the other block. Drill a 1/4" hole where the swage will go.

Thread a sufficiently long bolt through a fender washer, the block with
the plywood attached, the aluminum, the piece you dug out of the small
hole saw, the other 2x4 block, then another fender washer. Spin a nut
down to extrude the swage.

I don't know if this will work on .090, but I've used this technique on
thinner material.

Ernest,

I think I understand your description. I am going to send you a picture of
how I interpret your instructions. To me it seems like the tool you
describe is similar to a radio chassis punch. Is that correct? Instead of
punching a hole, your device pulls a slug of aluminum through a hole in the
plywood 2x4 side of the aluminum.

Also are you saying that once the tool and aluminum are all clamped
together the hole dug out of the hole saw will press through the aluminum
sheet creating the swaged hole? I do have to mention that the swage will
result in a flanged hole that I can use to weld my finger strainer and sight
gauge fittings. Should a hole larger than the 1/4" hole you mentioned be
drilled in the aluminum first so the male swage block will pull down through
easier to create the flange.

I'm all ears to solve this fabrication problem.

Ebby


"Ernest Christley" wrote in message
...
Ebby wrote:
Dear All,

I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge
weld the six fittings specified in the plans. Four of the fittings are
finger strainers and one is for the sight gauge. There is one more hole
on the top for the filler. As there are only six holes in three
different diameters, I was thinking about doing it using simple hand
techniques rather than expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the
holes over 3/8" steel plate with holes .180 oversize, then use a
polyethelene bossing hammer to swage the edge of the hole into the female
die hole. The holes in the female die would have the edges relieved to
accomodate a bend radius. It might be time consuming but educational.

Any advice or previous experience to share


A piece of 1/2" plywood and a couple chunks of 2x4. Tack plywood to one
of the blocks and use a small hole saw with a 1/4" centering bit to cut
the inside diameter of the swage. The piece that you dig from the hole
saw goes on one side of the aluminum. Use a bigger hole saw, centering on
the same 1/4" hole, cut the outside diameter of the swage, then drill the
1/4" hole all the way through the block. Drill a 1/4" hole through the
other block. Drill a 1/4" hole where the swage will go.

Thread a sufficiently long bolt through a fender washer, the block with
the plywood attached, the aluminum, the piece you dug out of the small
hole saw, the other 2x4 block, then another fender washer. Spin a nut down
to extrude the swage.

I don't know if this will work on .090, but I've used this technique on
thinner material.

Ebby wrote:
Ernest,

I think I understand your description. I am going to send you a picture of
how I interpret your instructions. To me it seems like the tool you
describe is similar to a radio chassis punch. Is that correct? Instead of
punching a hole, your device pulls a slug of aluminum through a hole in the
plywood 2x4 side of the aluminum.

Also are you saying that once the tool and aluminum are all clamped
together the hole dug out of the hole saw will press through the aluminum
sheet creating the swaged hole? I do have to mention that the swage will
result in a flanged hole that I can use to weld my finger strainer and sight
gauge fittings. Should a hole larger than the 1/4" hole you mentioned be
drilled in the aluminum first so the male swage block will pull down through
easier to create the flange.

I'm all ears to solve this fabrication problem.

Ebby

I think I answered you with direct email, but for the greater
audience.... I'd use the "chasis punch", as you describe it, to make the
swage and then use a step drill to cut the hole. That will help avoid
unwanted cracks around the hole from the stretching. You can make a
larger hole, but remember that you're stretching the aluminum. Keep the
hole as small as possible.



"Ernest Christley" wrote in message
...
Ebby wrote:
Dear All,

I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge
weld the six fittings specified in the plans. Four of the fittings are
finger strainers and one is for the sight gauge. There is one more hole
on the top for the filler. As there are only six holes in three
different diameters, I was thinking about doing it using simple hand
techniques rather than expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the
holes over 3/8" steel plate with holes .180 oversize, then use a
polyethelene bossing hammer to swage the edge of the hole into the female
die hole. The holes in the female die would have the edges relieved to
accomodate a bend radius. It might be time consuming but educational.

Any advice or previous experience to share

A piece of 1/2" plywood and a couple chunks of 2x4. Tack plywood to one
of the blocks and use a small hole saw with a 1/4" centering bit to cut
the inside diameter of the swage. The piece that you dig from the hole
saw goes on one side of the aluminum. Use a bigger hole saw, centering on
the same 1/4" hole, cut the outside diameter of the swage, then drill the
1/4" hole all the way through the block. Drill a 1/4" hole through the
other block. Drill a 1/4" hole where the swage will go.

Thread a sufficiently long bolt through a fender washer, the block with
the plywood attached, the aluminum, the piece you dug out of the small
hole saw, the other 2x4 block, then another fender washer. Spin a nut down
to extrude the swage.

I don't know if this will work on .090, but I've used this technique on
thinner material.

I'm thinking with .090" to stretch the hole would only be larger to accept a
larger bolt for stretching the swedge. Perhaps 3/8" instead of 1/4". I
have some experimenting to do.

Ebby


"Ernest Christley" wrote in message
.. .
Ebby wrote:
Ernest,

I think I understand your description. I am going to send you a picture
of how I interpret your instructions. To me it seems like the tool you
describe is similar to a radio chassis punch. Is that correct? Instead
of punching a hole, your device pulls a slug of aluminum through a hole
in the plywood 2x4 side of the aluminum.

Also are you saying that once the tool and aluminum are all clamped
together the hole dug out of the hole saw will press through the aluminum
sheet creating the swaged hole? I do have to mention that the swage will
result in a flanged hole that I can use to weld my finger strainer and
sight gauge fittings. Should a hole larger than the 1/4" hole you
mentioned be drilled in the aluminum first so the male swage block will
pull down through easier to create the flange.

I'm all ears to solve this fabrication problem.

Ebby

I think I answered you with direct email, but for the greater audience....
I'd use the "chasis punch", as you describe it, to make the swage and then
use a step drill to cut the hole. That will help avoid unwanted cracks
around the hole from the stretching. You can make a larger hole, but
remember that you're stretching the aluminum. Keep the hole as small as
possible.



"Ernest Christley" wrote in message
...
Ebby wrote:
Dear All,

I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge
weld the six fittings specified in the plans. Four of the fittings are
finger strainers and one is for the sight gauge. There is one more
hole on the top for the filler. As there are only six holes in three
different diameters, I was thinking about doing it using simple hand
techniques rather than expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the
holes over 3/8" steel plate with holes .180 oversize, then use a
polyethelene bossing hammer to swage the edge of the hole into the
female die hole. The holes in the female die would have the edges
relieved to accomodate a bend radius. It might be time consuming but
educational.

Any advice or previous experience to share

A piece of 1/2" plywood and a couple chunks of 2x4. Tack plywood to one
of the blocks and use a small hole saw with a 1/4" centering bit to cut
the inside diameter of the swage. The piece that you dig from the hole
saw goes on one side of the aluminum. Use a bigger hole saw, centering
on the same 1/4" hole, cut the outside diameter of the swage, then drill
the 1/4" hole all the way through the block. Drill a 1/4" hole through
the other block. Drill a 1/4" hole where the swage will go.

Thread a sufficiently long bolt through a fender washer, the block with
the plywood attached, the aluminum, the piece you dug out of the small
hole saw, the other 2x4 block, then another fender washer. Spin a nut
down to extrude the swage.

I don't know if this will work on .090, but I've used this technique on
thinner material.

This sounds like it might be a situation suited for aluminum braze to avoid
tooling up for the edge weld?

Todd


I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge weld
the six fittings specified in the plans. Four of the fittings are finger
strainers and one is for the sight gauge. There is one more hole on the
top for the filler. As there are only six holes in three different
diameters, I was thinking about doing it using simple hand techniques
rather than expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the
holes over 3/8" steel plate with holes .180 oversize, then use a
polyethelene bossing hammer to swage the edge of the hole into the female
die hole. The holes in the female die would have the edges relieved to
accomodate a bend radius. It might be time consuming but educational.

Any advice or previous experience to share

The EAA states that building your own airplane is educational. Well I'll
say!! I spent the day down in my shop working on the swedging problem. I
am pretty sure I have the answer to what needs to be done. As the alloy is
5052 and .090" in thickness, it seems to hve good workability.

I ended up making a device very similar to a regular Greenlee chassis punch
except instead of cutting a sharp edged hole, the male portion of the die
has relieved edges and has a diameter equal to the slug I want to weld into
the aluminum. Before I use the device, I cut a hole in the aluminum with a
bi-metallic hole saw slightly smaller than the finished hole size. It is
smaller by twice the length of the swedge flange. A 1/2 inch bolt goes
through the female die (oak plywood block nailed to another plywood block
which has been drilled to finished hole size plus twice the thickness of the
metal plus twice the bend radius for .090" aluminum) then through the
aluminun sheet then the male die. A large washer is placed over the male
die then the nut goes on. I spray WD40 on the threads and start to torque
the nut. I was surprised at how nicely the aluminum deflects downward. I
continue to wind the nut down until the male die is pulled through the piece
of aluminum. Originally I was using oak as the male die but it didn't hold
up. Then I switched to UHDPE. The PE went through fine but compresses
slightly so the hole ends up undersized. I ordered a piece of 3" steel bar
which I will turn down on a lathe to make the male dies. At this point I
think I have the problem solved. A lot of work for five holes. But as I
started my message it's all educational. Thanks Ernest!

Ebby


"Ernest Christley" wrote in message
.. .
Ebby wrote:
Ernest,

I think I understand your description. I am going to send you a picture
of how I interpret your instructions. To me it seems like the tool you
describe is similar to a radio chassis punch. Is that correct? Instead
of punching a hole, your device pulls a slug of aluminum through a hole
in the plywood 2x4 side of the aluminum.

Also are you saying that once the tool and aluminum are all clamped
together the hole dug out of the hole saw will press through the aluminum
sheet creating the swaged hole? I do have to mention that the swage will
result in a flanged hole that I can use to weld my finger strainer and
sight gauge fittings. Should a hole larger than the 1/4" hole you
mentioned be drilled in the aluminum first so the male swage block will
pull down through easier to create the flange.

I'm all ears to solve this fabrication problem.

Ebby

I think I answered you with direct email, but for the greater audience....
I'd use the "chasis punch", as you describe it, to make the swage and then
use a step drill to cut the hole. That will help avoid unwanted cracks
around the hole from the stretching. You can make a larger hole, but
remember that you're stretching the aluminum. Keep the hole as small as
possible.



"Ernest Christley" wrote in message
...
Ebby wrote:
Dear All,

I am starting to build my center section fuel tank and need information
about how to swage holes in the bottom of the tank so that I can edge
weld the six fittings specified in the plans. Four of the fittings are
finger strainers and one is for the sight gauge. There is one more
hole on the top for the filler. As there are only six holes in three
different diameters, I was thinking about doing it using simple hand
techniques rather than expensive tooling.

Here is my idea. The tank is .090" 5052. I planned on drilling holes
(.180+flange dimension) undersize in the aluminum. Then centering the
holes over 3/8" steel plate with holes .180 oversize, then use a
polyethelene bossing hammer to swage the edge of the hole into the
female die hole. The holes in the female die would have the edges
relieved to accomodate a bend radius. It might be time consuming but
educational.

Any advice or previous experience to share

A piece of 1/2" plywood and a couple chunks of 2x4. Tack plywood to one
of the blocks and use a small hole saw with a 1/4" centering bit to cut
the inside diameter of the swage. The piece that you dig from the hole
saw goes on one side of the aluminum. Use a bigger hole saw, centering
on the same 1/4" hole, cut the outside diameter of the swage, then drill
the 1/4" hole all the way through the block. Drill a 1/4" hole through
the other block. Drill a 1/4" hole where the swage will go.

Thread a sufficiently long bolt through a fender washer, the block with
the plywood attached, the aluminum, the piece you dug out of the small
hole saw, the other 2x4 block, then another fender washer. Spin a nut
down to extrude the swage.

I don't know if this will work on .090, but I've used this technique on
thinner material.

"Ebby" wrote in message
...
The EAA states that building your own airplane is educational. Well I'll
say!! I spent the day down in my shop working on the swedging problem.
I am pretty sure I have the answer to what needs to be done. As the alloy
is 5052 and .090" in thickness, it seems to hve good workability.

Ebby ..............

One of the Emeraude builders of my acquaintance faced a similar problem. He
needed to construct a "pass-through" in the center of his tank to allow the
carburetor cables to penetrate the aluminum. In his case, he swaged matching
holes in the front and back of the tank and then welded a piece of tubing
through and through. He built a swage similar to a chassis punch and it
worked rather well.

Regards,
Rich S.