BECC loaded cannon
| The volume chamber of the jr. was once used as the barrel on the original BECC, before (it was) Neild decided the 2-inch diameter was too big to use effectively with the given pressure. As we later found out, the rear cap was not properly glued onto the tube, and this part failed under pressurization. With a loud explosion, the rear cap blew clean off the volume chamber and shattered the night before the gun’s first use. Fortunately no one was injured because of this oversight, but the incident illustrates why safety should be paramount when building such a device. |
The BECC jr. has the same sliding barrel concept as the BECC. A T-connector holds the sliding barrel, and spaces the barrel from the volume chamber. This required a bit of work to bore out the T-connector enough for the barrel to slide freely, plus shaping the bottom of the T-connector to ride on top of the volume chamber. After finding that a clamp over the top of the T-connector caused too much pressure/friction on the piece, I followed the suggestion of team member Chris Demartini to run the clamp from the middle of the T-connector around the volume chamber. This required cutting two slots in the side of the T-connector.
The one aspect of the BECC that makes it a step forward in air cannon development is the breech loading system which allows for quick reloads. Unfortunately, the type of latch Neild used in the original was unique because it was taken from a specialty music equipment case. Finding another way to latch the barrel thus became the major challenge of this project. Finally I decided to try making an L-shaped bolt-action latch. This was done by sliding a bored-out collar with a screw protruding from it over the barrel. I then put a larger collar on the T-connector. The barrel collar, with its protruding screw, would slide into the T-connector collar, and the screw would lock into place in the L-shaped slot. Unfortunately, the explosion (mentioned earlier) that blew off the rear cap of the gun also damaged the screw mount in the barrel collar. This was fixed by clamping a hex wrench onto the barrel in the proper location, so it could be used to lock the barrel in place using the L-shaped slot. Overall the latter method probably offers better structural integrity.
For close-up pictures of the T-adapter and locking mechanism,
click on any of the following pictures to open a new window:
The major cosmetic improvement in the jr. model is in the mounting of the grip frame, CO2 tank, and battery box. The grip frame in this case is from an ACI Maverick. I mounted a small lever switch from Radio Shack (cat #275-016) inside the grip frame so that the trigger would activate it. To mount the grip frame, CO2 tank, and battery box, I bored out a 2-inch T-connector and a collar. In these pieces I mounted counter-sink screws which would act as studs on which to mount the grip frame and battery box. In the neck of the T-connector, I mounted another T-connector which was bored out enough to hold a 7 ounce CO2 tank.
Like the BECC, the jr. uses a Palmer Stabalizer to control pressure, and a guage for safety’s sake. Although the regulator will stop the pressurization at the desired level, under most circumstances I stop the flow of Co2 between shots with the use of an on/off valve on the 7 oz. tank. The BECCjr. requires 150 to 160 psi for best performance.
The battery box includes a light and safety switch to indicate when the cannon is armed. One of the modifications I have made since first writing this article is to relocate the switch to the rear of the box, and the light to the top. In its previous location on the side, the switch was prone to accidental activation when the cannon was laid on its side, with the light eventually draining the batteries. Like the BECC, the electric sprinkler valve on the jr. operates from two 9-volt batteries. All of the parts for the battery box, including switch, light, and 9-volt connectors came from Radio Shack.
The BECC jr. only holds 12 balls — exactly half the amount of the BECC. It uses the same dixie cup system to hold the balls in the shell. Despite the fact that part of my goal was to have a smaller, lighter version of the BECC, the jr. is still a fairly big cannon, and adds a lot to the load carried by most scanario players. In its first use at the “Battle for Earth” scenario game at Wayne’s World of Paintball in Ocala, Florida, before the game was over I found myself carrying only the cannon and leaving my regular paintball gun behind just because the load was excessive. However, I still had a lot of fun. These cannons are a blast to shoot becuase they kick a bit, and because they allow you to accomplish things (under the rules) that you can’t do with a regular gun. During the game, I eliminated 6 armored vehicles while firing 7 shots (thanks to 1 missed shot and a quick re-load), most of them from close distance. There is nothing I have experienced in paintball quite like hiding behind a tree waiting for an armored vehicle to come rolling into range.
A FINAL NOTE ON AIR CANNONS
As with the origial BECC, there are no drawn plans or parts list for this project. The final configuration was arrived at after a lot of experimentation, and lot of modification. There are no exact necessary dimensions for building these air cannons. The length, connecting type pieces, and method of powering the devices are fairly arbitrary. The most important aspect to consider is always safety. A visit to a hardware store and some creative thought can go a long way, but remember, safety first!
