How To Do It Flat Foam Farming - 2009/03

NO ONE EVER said that foam was the
new balsa. Both are essential in modeling
today, because they are lightweight and
available in varying densities to suit various
needs. Although balsa has foam beat hands
down in tensile and compression strength,
foam is more consistent in density. And in
thin sheets such as Depron, foam is far
lighter.
That’s an important point (and the
reason for this article) when considering
what material to use for indoor models.
Popular aircraft of the indoor ilk are mainly
constructed with materials such as Depron; I
won’t get into foam materials we’re used to
finding in beer coolers.
Depron comes in sheets that are
available in thicknesses ranging from 2mm
to 6mm. Companies such as Durobatics
have even more variations on the material
and have made it possible to produce RC
models that weigh less than an ounce.
Practical airplanes to fly indoors are the
aerobatic types we call “foamies.” Made
from flat foam material, they offer
performance that surely has Sir Isaac
Newton rolling over in his grave. These
FoamWerks Tools
Midwest Products Co., Inc. recently began
distributing a line of unique products from
FoamWerks. Originally developed for foam
board, these implements are perfect for use with
any flat foam material that is employed in
aeromodeling.
These tools are accurate and easy to use, and
they cut circles, straight edges, beveled edges,
V grooves, small holes, and rabbet edges. All
feature quick-change blades and ergonomic
designs. Also included are innovative
accessories such as channel rail, tape, an
accessories kit and clips, a full-line of
replacement blades, and a full-color project
book.
Flat foam is a delightful material to work
with, because its density is consistent and it can
be smoothed and painted easily. A sharp cutting
blade is essential, and even a steady hand can
wander from course, no matter how accurate a
template is. FoamWerks tools eliminate many
opportunities for sloppiness, no matter what
material is being employed.
The best thing about the FoamWerks line is
that, since it is designed to be used frequently,
the tools are strong and user friendly. In
addition, they work like die-cutters, so they
leave no dust or annoying mess. They also
make projects more efficient, since the master
and waste material are held intact with smooth
edges. MA
—Michael Ramsey
Sources:
Midwest Products
(800) 348-3497
www.midwestproducts.com
models seem to defy the laws of physics,
thanks not only to the electric power and
battery systems (power-to-weight ratio), but
also to their light wing loadings.
Lately I’ve been scratch-building my
foamies from a material that Midwest
Products distributes called Cellfoam 88. It’s
offered in conveniently sized two-sheet sets
that consist of pieces that are 11.5 x 47
inches in dimension and come in 3mm,
5mm, and 10mm thicknesses.
Cellfoam 88 is slightly heavier than
Depron, but it seems less brittle and has a
smoother surface texture. Its bright white
color is extremely pleasing.
Ed Rogala of Midwest and I have been
experimenting with Cellfoam. Much of what
you read about in this article is a
collaboration of our ideas, but Ed’s
materials are shown in the photos; he let me
borrow them so we could present this
feature to you.
Sheet foam material is incredibly easy with
which to work. As easy as building a paper
airplane, almost anything you can think up
that has wings and a properly located CG
will fly. How it flies is up to the creator, but
changes and new prototypes are possible
with just an evening’s worth of pleasantries
in the workshop.
Roughly a year ago, Jason Noll showed
up at the JR Indoor Electric Festival with
one of his Vrolet biplanes. Its 3mm sheet
material was routed out in key areas, leaving
a practically paper-thin layer on the opposite
side. The material that was not ground away
left a warren-truss-looking structure.
FancyFoam.com made the kit and did all the
precision machining on CNC equipment.
That’s too much work for the average
modeler, I thought at the time. And the
weight savings hardly seemed worth it.
A few months later, at E-Fest, several
modelers had homemade foamies with
routed-out components. This trick was
getting done at home, and it seemed to make
a difference—not only in the airplanes’
weight, but it also helped in the effort to
promote airframe drag that aids in flying the
model more slowly.
Ed got to work and found out that
Dremel had the right tool for the job; only a
slight modification was necessary to do
what we needed. However, the process is
extraordinarily messy.
This is the part where we remind you
about shop safety. There’s no better way to
create a mess of dust than to take a highspeed
tool equipped with a carbide tip to a
material that can not only be made almost as
light as air, but that is also as plentiful.
When sanding or routing the foam, wear
a face mask and ventilate the workshop as
well as possible. A shop vacuum with a
brush attachment following the router helps
tremendously, but it’s still a mess.
The Dremel Multipurpose Cutting Kit
was modified with a widened base made
from 1/8-inch-diameter acrylic window-pane
62 MODEL AVIATION
material (from the hardware store). Midwest
sells .118-inch-thick Clear Polyester Super
Sheets (item 703-06) with dimensions of 7.6
x 11 inches.
The acrylic was cut into a 6-inch disk,
and a 3/8-inch-diameter hole was drilled in its
center. A 3/8-inch-long, 3/8-inch-outside
diameter (OD) brass tube will be pressed and
glued in place in the center of the disk. The
tube will act as a fence around the 5/16-inch,
high-speed Dremel cutter bit that will be
chucked into the Dremel tool.
Zap-A-Goo adhesive is used to glue the
acrylic plate to the router attachment’s fiberreinforced
nylon. Sanding the base of the
router attachment improves the glue bond. If
you will want to return the attachment to its
stock form, leave the material smooth and
the joint can be separated fairly easily.
The depth of the tool bit depends on the
template and working material. The 3/8-inch
brass sleeve should be set to a depth that is
typical of the routing template. I used 5mm
Cellfoam 88. The tool bit’s shank should be
set as deep as possible into the motor-tool
collet and still be extended far enough to
remove the elected amount of material from
the foam.
Foam sheet originates from a roll and is
made into sheets through a heating and
compression process that gives the material a
crisp skin. We can rout out the foam material
practically to the depth of that “skin,” which
is as thin as Mylar.
A model that is modified to this extent is
more fragile. But there’s no such thing as
too light for indoor aerobatics.
The amount of weight that can be saved
is up to the user, and custom templates must
be made for a particular part. The easiest
method is to trace the part onto the template
material and mark the critical areas where
the part material should stay the stock
thickness.
Areas such as hinge lines, outside edges,
and butt joints are important areas where the
meat of the foam should be left. The rest is
flab.
Leave approximately 1/4-1/2 inch of
material around the hinge lines and
perimeter. The ribs and crossmembers
should be 3/8-1/2 inch wide. Keep in mind
that the corners will have a 3/16-inch radius
because of the brass sleeve that shields the
5/16-inch tool bit.
You could add 1/32 inch to the opening’s
overall perimeter, to allow for the space
between the brass sleeve and tool bit. I
typically don’t worry about that variance.
The cutout areas shouldn’t be wider than
half the thickness of the acrylic baseplate; in
this case, that’s 3 inches. Whenever
possible, the routed surfaces should be on
the bottom. Which side of the fuselage is
routed is up to the builder; I chose the
starboard side.
Once the template is laid out, remove the
cutout area with an X-Acto knife. Reference
the location of the part on the backside of
the template so it can be accurately
positioned and temporarily secured with
tape.
Be patient when routing the material.
I’ve found that the #1 speed on the Dremel
tool is sufficient and doesn’t cause the
material to overheat and bead at the edges
(too much).
Start by removing/routing the outline
material, not pressing hard enough against
the template to dent the edges. Make a
second pass, this time removing more
material toward the inside. After roughly
three passes all the way around, start
plowing out the center. It’s like mowing the
lawn.
Rout out the planned materials one by
one. Check the tool setting periodically to
make sure that it hasn’t shifted.
I suppose it would be possible to apply
this routing technique to balsa; as a matter of
fact, I’m sure it is. If anything, this method
should shed some light on how far materials
such as sheet foam can be pushed to suit our
modeling needs.
Experiment with this idea for yourself,
and always exercise shop safety. MA
Michael Ramsey
[email protected]
Sources:
Midwest Products
(800) 348-3497
www.midwestproducts.com
RCfOAM (sells Depron)
(404) 556-9117
www.rcfoam.com
Durobatics
(315) 264-2064
www.durobatics.com
Dremel
(800) 437-3635
www.dremel.com
Materials List:
Dremel Multipurpose Cutting Kit (item 565)
Dremel high-speed bit (item 115)
1/8-inch clear acrylic
Zap-A-Goo adhesive
3/8-inch OD brass tube (3/8 inch long)
Template material (chipboard or foam sheet)

NO ONE EVER said that foam was the
new balsa. Both are essential in modeling
today, because they are lightweight and
available in varying densities to suit various
needs. Although balsa has foam beat hands
down in tensile and compression strength,
foam is more consistent in density. And in
thin sheets such as Depron, foam is far
lighter.
That’s an important point (and the
reason for this article) when considering
what material to use for indoor models.
Popular aircraft of the indoor ilk are mainly
constructed with materials such as Depron; I
won’t get into foam materials we’re used to
finding in beer coolers.
Depron comes in sheets that are
available in thicknesses ranging from 2mm
to 6mm. Companies such as Durobatics
have even more variations on the material
and have made it possible to produce RC
models that weigh less than an ounce.
Practical airplanes to fly indoors are the
aerobatic types we call “foamies.” Made
from flat foam material, they offer
performance that surely has Sir Isaac
Newton rolling over in his grave. These
FoamWerks Tools
Midwest Products Co., Inc. recently began
distributing a line of unique products from
FoamWerks. Originally developed for foam
board, these implements are perfect for use with
any flat foam material that is employed in
aeromodeling.
These tools are accurate and easy to use, and
they cut circles, straight edges, beveled edges,
V grooves, small holes, and rabbet edges. All
feature quick-change blades and ergonomic
designs. Also included are innovative
accessories such as channel rail, tape, an
accessories kit and clips, a full-line of
replacement blades, and a full-color project
book.
Flat foam is a delightful material to work
with, because its density is consistent and it can
be smoothed and painted easily. A sharp cutting
blade is essential, and even a steady hand can
wander from course, no matter how accurate a
template is. FoamWerks tools eliminate many
opportunities for sloppiness, no matter what
material is being employed.
The best thing about the FoamWerks line is
that, since it is designed to be used frequently,
the tools are strong and user friendly. In
addition, they work like die-cutters, so they
leave no dust or annoying mess. They also
make projects more efficient, since the master
and waste material are held intact with smooth
edges. MA
—Michael Ramsey
Sources:
Midwest Products
(800) 348-3497
www.midwestproducts.com
models seem to defy the laws of physics,
thanks not only to the electric power and
battery systems (power-to-weight ratio), but
also to their light wing loadings.
Lately I’ve been scratch-building my
foamies from a material that Midwest
Products distributes called Cellfoam 88. It’s
offered in conveniently sized two-sheet sets
that consist of pieces that are 11.5 x 47
inches in dimension and come in 3mm,
5mm, and 10mm thicknesses.
Cellfoam 88 is slightly heavier than
Depron, but it seems less brittle and has a
smoother surface texture. Its bright white
color is extremely pleasing.
Ed Rogala of Midwest and I have been
experimenting with Cellfoam. Much of what
you read about in this article is a
collaboration of our ideas, but Ed’s
materials are shown in the photos; he let me
borrow them so we could present this
feature to you.
Sheet foam material is incredibly easy with
which to work. As easy as building a paper
airplane, almost anything you can think up
that has wings and a properly located CG
will fly. How it flies is up to the creator, but
changes and new prototypes are possible
with just an evening’s worth of pleasantries
in the workshop.
Roughly a year ago, Jason Noll showed
up at the JR Indoor Electric Festival with
one of his Vrolet biplanes. Its 3mm sheet
material was routed out in key areas, leaving
a practically paper-thin layer on the opposite
side. The material that was not ground away
left a warren-truss-looking structure.
FancyFoam.com made the kit and did all the
precision machining on CNC equipment.
That’s too much work for the average
modeler, I thought at the time. And the
weight savings hardly seemed worth it.
A few months later, at E-Fest, several
modelers had homemade foamies with
routed-out components. This trick was
getting done at home, and it seemed to make
a difference—not only in the airplanes’
weight, but it also helped in the effort to
promote airframe drag that aids in flying the
model more slowly.
Ed got to work and found out that
Dremel had the right tool for the job; only a
slight modification was necessary to do
what we needed. However, the process is
extraordinarily messy.
This is the part where we remind you
about shop safety. There’s no better way to
create a mess of dust than to take a highspeed
tool equipped with a carbide tip to a
material that can not only be made almost as
light as air, but that is also as plentiful.
When sanding or routing the foam, wear
a face mask and ventilate the workshop as
well as possible. A shop vacuum with a
brush attachment following the router helps
tremendously, but it’s still a mess.
The Dremel Multipurpose Cutting Kit
was modified with a widened base made
from 1/8-inch-diameter acrylic window-pane
62 MODEL AVIATION
material (from the hardware store). Midwest
sells .118-inch-thick Clear Polyester Super
Sheets (item 703-06) with dimensions of 7.6
x 11 inches.
The acrylic was cut into a 6-inch disk,
and a 3/8-inch-diameter hole was drilled in its
center. A 3/8-inch-long, 3/8-inch-outside
diameter (OD) brass tube will be pressed and
glued in place in the center of the disk. The
tube will act as a fence around the 5/16-inch,
high-speed Dremel cutter bit that will be
chucked into the Dremel tool.
Zap-A-Goo adhesive is used to glue the
acrylic plate to the router attachment’s fiberreinforced
nylon. Sanding the base of the
router attachment improves the glue bond. If
you will want to return the attachment to its
stock form, leave the material smooth and
the joint can be separated fairly easily.
The depth of the tool bit depends on the
template and working material. The 3/8-inch
brass sleeve should be set to a depth that is
typical of the routing template. I used 5mm
Cellfoam 88. The tool bit’s shank should be
set as deep as possible into the motor-tool
collet and still be extended far enough to
remove the elected amount of material from
the foam.
Foam sheet originates from a roll and is
made into sheets through a heating and
compression process that gives the material a
crisp skin. We can rout out the foam material
practically to the depth of that “skin,” which
is as thin as Mylar.
A model that is modified to this extent is
more fragile. But there’s no such thing as
too light for indoor aerobatics.
The amount of weight that can be saved
is up to the user, and custom templates must
be made for a particular part. The easiest
method is to trace the part onto the template
material and mark the critical areas where
the part material should stay the stock
thickness.
Areas such as hinge lines, outside edges,
and butt joints are important areas where the
meat of the foam should be left. The rest is
flab.
Leave approximately 1/4-1/2 inch of
material around the hinge lines and
perimeter. The ribs and crossmembers
should be 3/8-1/2 inch wide. Keep in mind
that the corners will have a 3/16-inch radius
because of the brass sleeve that shields the
5/16-inch tool bit.
You could add 1/32 inch to the opening’s
overall perimeter, to allow for the space
between the brass sleeve and tool bit. I
typically don’t worry about that variance.
The cutout areas shouldn’t be wider than
half the thickness of the acrylic baseplate; in
this case, that’s 3 inches. Whenever
possible, the routed surfaces should be on
the bottom. Which side of the fuselage is
routed is up to the builder; I chose the
starboard side.
Once the template is laid out, remove the
cutout area with an X-Acto knife. Reference
the location of the part on the backside of
the template so it can be accurately
positioned and temporarily secured with
tape.
Be patient when routing the material.
I’ve found that the #1 speed on the Dremel
tool is sufficient and doesn’t cause the
material to overheat and bead at the edges
(too much).
Start by removing/routing the outline
material, not pressing hard enough against
the template to dent the edges. Make a
second pass, this time removing more
material toward the inside. After roughly
three passes all the way around, start
plowing out the center. It’s like mowing the
lawn.
Rout out the planned materials one by
one. Check the tool setting periodically to
make sure that it hasn’t shifted.
I suppose it would be possible to apply
this routing technique to balsa; as a matter of
fact, I’m sure it is. If anything, this method
should shed some light on how far materials
such as sheet foam can be pushed to suit our
modeling needs.
Experiment with this idea for yourself,
and always exercise shop safety. MA
Michael Ramsey
[email protected]
Sources:
Midwest Products
(800) 348-3497
www.midwestproducts.com
RCfOAM (sells Depron)
(404) 556-9117
www.rcfoam.com
Durobatics
(315) 264-2064
www.durobatics.com
Dremel
(800) 437-3635
www.dremel.com
Materials List:
Dremel Multipurpose Cutting Kit (item 565)
Dremel high-speed bit (item 115)
1/8-inch clear acrylic
Zap-A-Goo adhesive
3/8-inch OD brass tube (3/8 inch long)
Template material (chipboard or foam sheet)