The original gun was a Splatmatic XJ40 .40 cal we
purchased on E-Bay. Unfortunately, we didn't take a before picture,
but here's a picture from the seller we bought it from.
The plastic casing is removed from the gun, along with the small CO2
cylinder holder which is replaced by a CO2 feed line from a larger
bottle. A servo is attached to the handle to pull the trigger.
Click Photo For Enlargement (115 Kb)
A close-up of the trigger assembly.
We (i.e., Brian) decided to use the
grip frame for a nice mounting point for the servo.
We are in the process of re-designing the
trigger assemble to mount the servo below the gun body
and to use a short section of bicycle brake cable to
actuate the trigger in leu of the rod. The width of the trigger
assembly is one of our concerns.
We turned down the barrel to allow a shroud to mimic
the barrels of the scale craft and to allow a nice
bushing to be installed as an elevation pivot point
and mounting location for the jack-screw assembly.
Also shown here is the CO2-line connection that replaces the small
CO2 cartridge provided with the gun.
The valve assembly is a two piece press fit with a
set screw. The cup seal is what we were concerned
about when we were pressing out the valve. But
luckily we were able to remove it without impacting
the cup seal. We used a small arbor press to push it
out and the plunger for the 12gram cartridge was where
the 90 degree elbow resides now. It was also pressed
into the valve body and needed to be milled out (we
had the tools available so milling seemed easier). In
the process we tapped for a standard 1/8 NPT and we
now have the ability to mount a 3.5 - 7 oz. CO2 tank in
the hull.
A simple straight-line magazine approximately 10 inches long
is used to hold the 20 rounds (40 cal) allowed in an armored car.
The feed mechanism uses the wound springs from a key
retract that most handymen use to hold their keys to
their belt. We chose this method since tension is
adjustable by how much chain you remove before you
attach it to the follower and the length seems to
sufficient for longer, odd-shaped magazines.
The jackscrew assembly is used to mount the gun in the turret.
Another view of the jackscrew assembly.
Click Photo For Enlargement (107 Kb)
The completed gun assembly ready to go in an armored car
(as soon as we decide which one to build)
A standard lazy-susan turntable will be used to rotate
the turret.
The belt and gears are our idea for turret traverse
and we are thinking of mounting a modified servo (cs-80
cirrus type with external potetionmeter) to the hull
and using the reduction of the belt to turn a geared
collar on the turret itself. Again, as we get closer
to building the hull, the design might change.
