Maybe you’ve got a replica World War 1 Nieuport that need a machine gun on the upper wing for that final touch. Maybe you’re a Great War re-enactor, needing machine gun for your infantry squad. Or maybe you’re a Star Wars Cosplayer, who needs a blaster for a heavy-weapons unit.
A replica Lewis Gun fits the bill for all of you. Yes, even you budding Imperial Storm Troopers out there… that’s a completely original Lewis Gun the Trooper in the picture to the right is carrying (sans ammunition drum).
This web page provides instructions on how to build one,
what's more, it includes Computer Aided Design (CAD) models in
Solidworks that allow you to print out most of the parts on
common 3D printers.
While I built the prototype using a combination of wood and
3D-printed parts, all the parts of the replica could be done
with a 3D printer. However, some of the parts are too
large to be made on the common consumer printers. It's
easier to do them in wood. Otherwise, you'll need to
split the parts in your drawing package and glue them back
together after they print individually.
To print out the parts, you'll need Solidworks or a CAD
program that can read Solidworks files. Even if you
don't have a 3D printer, Solidworks can generate standard
drawings that will aid you scratch-building one from wood.
In the early 1900s, an American inventor, Doctor Samuel
McClean, developed a water-cooled machine gun.
Unfortunately, it was clear that the gun violated the patents
held by Hiram Maxim
In desperation, the investors asked Major Isaac Newton Lewis if he could salvage their investment. Major Lewis saw the basic mechanism could be adapted to produce an AIR-COOLED machine gun
Major Lewis’ result was a marvel. It weighed just 30
pounds, completely loaded with a 47-round drum. It was
cooled by the bullet exiting the barrel from the inside of a
tube, which sucked cooling air in the other end.
Competing machine guns were liquid-cooled, using cloth belts to carry the ammunition that would get dirty and well in combat conditions. They were heavy… 50 pounds for the gun, 30 pounds for the tripod, a cask of coolant, etc. It took a full squad to support the gun.Because of these issues, conventional machine guns were considered defensive weapons only. But the Lewis gun needed just a gunner and another man to carry spare drums. It could go on the offensive.
There are several factors involved in replicating the
Lewis Gun. The primary one is the desired accuracy.
You have to decide if you're looking for "20 Foot", "10
Foot," "Five Foot," "Three Foot", or "Hands On" accuracy.
A "20 Foot" Lewis gun will look real to an observer 20
feet way, a "10 Foot" one at ten feet, etc.
However, this does depend on the KNOWLEDGE of the observer. Someone who KNOWS Lewis Guns will be able to tell that a "Ten Foot" replica is wrong, even twenty or thirty feet awaWhen I make replicas like this, I shoot for "three foot" accuracy...basically for a visitor to step into my home office, see the replica perched there, say, "Holy S***!"...then, depending on their background, they notice the discrepancies as they come closer.
Here was a way to DO those little
fiddly bits. I’m
a member of the Experimental Aircraft Association, and one
member perk is the educational version of Solidworks, a
very powerful CAD (computer-aided design) tool. If you’re buying
a copy outright, Solidworks costs $10,000…yet, as an EAA
member, I could download a free copy!
So I started teaching myself
Solidworks, which was kind of a slog since it’s a
professional tool, not designed to molly-coddle ordinary
mortals. As I
got better at it, I realized that more and more of the
Lewis Gun design could be printed on my Epson 3D
printer. I replaced several parts I'd already made
from wood with 3D-printed versions.
The picture to the right illustrates the issue. These are the components that fit at the end of the receiver where the gas tube and barrel emerge. You can see the simple wood version I did…next to the version generated by the 3D printer. The vertical shelf would have had to have been a piece of 1/4” wood glued to the base piece. The 3D version is much, MUCH better, especially as I was able to quickly change the design as research showed what the actual piece looked like.
And it was a LOT easier to re-do parts when I found
errors. The shelf on this receiver end was too
long. I went back into Solidworks, edited the part
design, sent it to the printer, and had a new one in a
A similar mistake in wood might not have been too difficult to fix. But imagine finding, for instance, that the two holes had the wrong spacing? The whole part would have probably had to have been scrapped. Instead of just making a minor change on the computer, and re-printing it out.
So...ultimately, how accurate is my design?
Dimensions, etc. are pretty close. I have an image
of an original Savage Arms three-view drawing, which I
imported into a image tool and resized so I could directly
determine the sizes and shapes of various components.
Otherwise? Well, I’ve taken a lot of liberties in the name of making the replica easier to build. Primary variations have to do with the surface detail on the receiver, the main body. I’ve taken some short cuts there.
MOST people who see your replica, or the pictures of it, won’t be able to tell the difference.
If some aspect bugs you…well, then crank up Solidworks
and fix it. That’s the beauty of this project; it
generates a good base for doing some fine detail.
For the Solidworks
design I posted, the receiver is just a simple 1"x2"x11.5 block of wood...but two side-pieces are attached. These side-pieces implement the surface detail I made in wood for my model, but you sure can modify them if you wish!
The figure below shows what I call the various portions
of the replica. The “Main Body” is the receiver, the
“Barrel” is above the “Gas Tube”, the Top Plate supports
the drum (not shown) and includes the base for the main
sight. The Hand Grip includes the trigger, and the
“Spring Housing” with its wind-up dial set right in front
The main body is the fundamental structure of the replica. It’s made of wood, 1” wide, 2” high, and 11.5 inches long. It has the pilot holes for attaching the top plate, hand grip, and spring housing. I often refer to it as the "Receiver."
The main body can be done on a 3D
printer…but it’s 11 1/2” long. That’s too
long for my printer.
Since it is the fundamental structure, I used wood. The Main Body is 1” wide, 2” high, and 11.5 inches long. Note the slot…this is where the bolt slides, and the charging handle would be installed.
While I made the hand grip and the spring housing from wood as well, I have included the Solidworks files. You can get the shapes and dimensions from them. Locating holes are provided in those Solidwork parts, although of course, if you’re making them from wood, just put the holes where necessary to get it to fit.
The spring housing shows a bit of filet on top…this is accurate; the housing is really a separate component.
Included in the package are “Hand Grip Right” and “Hand Grip Left”. These are thin plates that attach to the hand grip. On the actual gun, these would be thin wood, shaped to smooth the grip to the user’s hand.
The standard Lewis has shaping on the sides, not just the slab sizes that the 1x2x11.5 wood block provides. For one thing, the width of the body has to be 1.5” in back, to fit the rear grip. Looking at the basic design, there’s a “bulge” at the top of the receiver basically around the extended line of the barrel; this bulge blends into the 1/4” thickness that’s added to the end of each side.
I did all this shaping manually, using segments of
dowels, pieces of wood, and some plastic angles.
This picture shows the in-process look....I did a lot
of Bondo work and sanding to get things really smooth.
What I did for the Solidworks model was design the detail as an overlay, to be attached to the sides of the main body. You see those back on the Main Body illustration. These can be printed, then glued to the main body to give some semi-realistic shaping to the sides of the main body.
“Semi-Realistic.” The design is
evocative of the actual Lewis, but not perfect. Feel
free to experiment and improve.
The 1/2” holes in the main body match the holes in the receiver end, while the 1/2” long extensions of the barrel and gas tube spacers insert into these holes. The barrel holder slides over the end of the spacers, and the spacers include 1/4” holes for dowels to connect them to the main barrel and gas tube.
Here’s the dimensions of the holes that need to
be bored into the end of the main body:
is VERY awkward to do. I
made my main body out of two 1/2” pieces of wood, and carved
out SQUARE holes using the table saw:
Now: I made the barrel and gas tube spacers on a lathe. I’ve included Solidworks models for these, so you can probably far more easily print them out than go buy a lathe. If I were to build a second Lewis, I’d do it this way.
HOWEVER: The attachment of the spacers to the body,
and the barrel and gas tubes to the end of the spacers, is
probably the most critical portions of the design, as far
as the STRUCTURE are concerned. The barrel and the
gas tubes themselves attach to the spacers using short
1/4” dowel pins.
This is adequate for a ground display, or running around in trenches with re-enactors, or marching through a convention with your fellow cosplayers. I am, though, skittish about this for replicas intended to be mounted to actual aircraft.
I think the turned wood versions are stronger than a 3D printed version would be…but you’re still stuck with the interface between the spacers and the tubes. I think epoxy probably works better between the wood spacers and the wood barrels, vs. a plastic 3D printed spacer and the wooden barrel/gas tube.
If you’re intending to mount this on an aircraft, come up with ways of beefing up this interface. Possibly use a 1/4” steel rod into the main body, through the inside of the spacers, and an inch or three into the barrel and gas tubes.
There are other options, too, which I’ll discuss in the next section.
By the way, these spacers and the barrel/gas tube require
a hole drilled into the ends dead-center to take the dowel
that connects them to the other portion. There are
three Solidworks “Drill Guide” parts….one for 3/4”, one
for 1”, and one for 1 1/4”. These are like stool
caps. They slide snugly over the end of the wooden
dowels, and including teeny tiny hole dead center.
Use that for drilling into the exact center of the rods.
While I include a Solidworks version in the package, the “Gas Tube” is a 3/4” wooden dowel, and the barrel starts as a 1-inch dowel, tapered from one inch at the receiver end to 5/8th at the muzzle.
One of the classic features of the Mark III Lewis is that
tapered barrel. I love the look, and actually bought
a small wood lathe specifically so I could taper a dowel
to get that look (I’m always looking for an excuse to buy
tools). This figure shows the stock barrel system.
By the way, see the nut at the base of the barrel?
Completely non-functional. Just glues in place as a
bit of additional detail.
The Barrel Holder for the Mark II and Mark III
are pretty historically accurate; I copied the
design from an original Savage Arms drawing.
It includes a pair of flanges at the bottom to
allow the gun to be attached to a solid
mount. This is probably how your replica
would attach to an airplane. There are
additional flanges on the sides where clamp
handles were attached.
There’s a lot of load on the Barrel Holder. I’m not too confident that a 3D model made from plastic will be up to the job on an airplane.
Alternatively, you could have this machined out of aluminum (or 3D printed from metal). Even a wood replica might be stronger.
One possibility is shown below. Wrap the channel of the barrel holder with a stainless steel strap, leading down to both mounting holes. This way, the strap is there to take the load.
The Top Plate sits on top of the Main
Body. There are a line of holes in the
mail body; these line up with the centerline
of the Main Body. The top plate should
be positioned so that the back edge of the
sight mount lines up with the back edge of the
main body. The design includes a sort of
T-Shaped “Follower” that helps back up the
Doing further research, I think this
“follower” was actually one-piece with the top
plate. But one of the #6 countersunk
screw holes go through the top plate right
about in the middle of the “Follower” so that
makes things easier to screw together.
Plus, the 3D-printed follower will have better
detail than if a single part.
The aircraft Lewis Guns replaced the
wooden stock of the infantry model
with a small hand grip. I
debated trying to build this from
aluminum and wood, but by that point,
I was getting confident enough with
Solidworks that was able to tackle
it. It’s four inches from the
top and bottom insides of the grip…
you’ll need a length of 3/4” or
7/8” dowel. In my case, having a
lathe, I actually turned a nice
double-tapered grip. The hole in
the grip is sized for #6 screws.
The Solidworks package includes a drum…but I didn’t print it out and use it. It’s too large for my 3D printer.
The drum kit I purchased from Foxflier () was MORE than
adequate. I needed to make a
bracket for the top of the drum,
but it did come out nicely.
They sell the drum alone for
$35. It’s the large aircraft
drum, but Infantry users can just
slice it like a bagel to simulate
the 47-round drum.
Lewis gun drum handles varied in
design, but most included a
leather strap like my picture
shows. I bought some buckles
and other hardware at a craft
One thing you’ll find is that wood surfaces tend to show their grain through any paint that applied. So you’ll need to apply several coats of primer, sanding things down to try to smooth out the grain. That's one advantage of the 3D printer output, the plastic paints very well.
I love working with oak (it’s
tough and doesn’t splinter), but
it’s got a hellaciously deep
grain. Woods like pine and
poplar finish better, but, of
course, aren’t as strong.
I have a preferences for using
stock paints on dummy guns like
this. The trouble is, it’s
impossible to find a good
“gunmetal gray”. I found a
dark gray primer that was actually
pretty good, but it had a matte
finish. Matte gets that way
by having a rough surface; to me,
it doesn’t simulate metal very
What I’ve been doing is painting
with GLOSS black, then spraying it
with a clear matte finish.
It still has a touch too much
shine to it, but does look a lot
like smooth metal.
As a crowning touch, I use a
product called “Rub ‘n Buff,” in
silver. This is, essentially,
paint in a paste form. Put a
TINY amount of it on a fingertip,
and rub any bit of
protrusion. This does a
beautiful simulation of paint
rubbing away. Do it on
several outside edges, the area
around the trigger, etc.
It’s easy to go too far (that’s
what happened with that drum
picture above) but it does make
things really snap out.
Keep in mind that the rear grip
was basically a bent metal
strap…that’s why it’s painted
silver on my replica. The
vertical dowel would be wood…as
would the left and right hand