Image 1; Picture of Rapid Fire 20 with Outer Black Case Removed
This is a modification for the Nerf Rapid-Fire 20 Piston. It requires patience and attention to detail. If you are new to modding, I would recommend you complete several simpler mods before attempting to perform this more complicated one.
Materials Required
Unscrew everything and open it all up. When you are separating the two gray pieces, you will have trouble down by the front end of the pump shaft where the two pieces of the case may be glued together. Slowly pull the two gray pieces farther and farther apart until the glue is overcome. A similar problem will arise when you are taking off apart the red pieces. There is a red ring that secures the two red pieces at the back end of the pump shaft. Slowly pull apart the two pieces, and the red part should come off without breaking anything. After opening the gun, the internals should look like image 2 below (the back red portion hasn't been removed in the picture, but you want to do that too). Although the picture I have is pretty good about explaining where the various tubes and such go, it still wouldn't hurt to carefully examine where everything lies, and what goes to where, to aid in the reassembly process. For the piston mod, you don't need to remove the gray piece that holds the pressure chamber in place.
Image 2; Picture of Rapid Fire 20 internals (red
portion not removed)
In order to work on the piston, you will first need to remove it from the gun. After taking apart the two big red pieces from the back of the gun, remove the outer clear cylinder that protects the piston. Just pick it up out of the red part, and slide it off the piston (you will need to unscrew the black piece on the front of the piston. Remove the piston from its tubing by unscrewing the white plastic piece that is over the tubing. After unscrewing it and sliding it down the cord, pull off the tubing. It may be easy, or it may require some twisting with pliers (be gentle). After removed, the piston should look like image 3.
Image 3; Stock RF20 Piston
In order to gain access to the piston spring, we will need to saw into the piston. The first cut deals with the clear part of the piston. You will need to make sure you don't cut into the spring or the inner white tube. Simply cut a circle around the end of the piston, close to the red spacer. Try to minimize (jumps) in the cut. (Don't make a jagged cut).
Image 4; Partially Cut RF20 Piston
The second cut we will make on the piston will be epoxied back together toward the end of the mod (step 9). In order to ensure a good seal in step 9, we will cut the middle portion of the piston in the shape of a 'V' (see image 5). Before making the cut, mark a long line with permanent marker so it is easier to identify which side is which when you are reattaching the two pieces. Push the red spacer down towards the opposite end of the piston (compress the spring) and cut at a downward slant halfway through the tube. Reposition your saw to the opposite side of the piston, and mirror the previous cut.
Image 5; Cut RF20 Piston
This is definitely the hardest part of the mod. When you cut the clear portion of the piston, a clear ring remained on the red spacer. This clear ring is glued on. If yours isn't, then thank God. If it is (like all of mine), you will need to remove it by any means necessary. The red lip on the end of the spacer isn't crucial, but you should probably leave at least 40% of it on. The red stubs that are sticking out of the spacer must not be harmed. On one of my spacers, I slowly hammered, bit by bit, a small screwdriver into the space between the clear plastic and the red spacer. I eventually broke the screwdriver. I have had success using a small file, and gradually sanding away the majority of the clear plastic (making sure not to harm the red protrusion). I once used a scroll saw to cut it away (the red lip isn't vital). You are likely to become frustrated during this part of the mod. Feel free to try whatever methods come to mind for removing the clear portion, but make sure not to cut into the red studs. NOTE: Some of the spacers are easier to clean than others. Some take no time at all, and some will take more time than all other steps of the mod combined. I hope you get one of the easy ones.
Image 6; Cleaned Spacer in Piston
This step is where having a scroll/band saw comes in handy. First, put the cleaned spacer up to the clear piston chamber (make sure the chamber isn't jagged. If it isn't, then cut it down further). Carefully mark where the protrusions will be (I used a sharpie). Cut into the piston a little bit, and test the spacer to make sure you have cut at adequate intervals. If the holes you have made are way off, then make new ones. After ensuring correct positioning, cut the holes farther down. Push the spacer all the way in to test the slots. Push the spacer in how far it needs to go, and make a mark parallel to where the dimple is. Make marks on both sides so that when you cut the holes, you can push the slider in and turn it so that it locks (it will be holding the spring in).
|
|
|
|
Image 7; Spacer Slots Part 1 |
Image 8; Spacer Slots Part 1 |
Image 9; Spacer Slots Part 3 |
The entire goal of this modification is to increase the amount of resistance the spring in the piston supplies. The more you stretch the spring, the greater the strength per shot, but if you stretch the spring too much/replace it with too strong a spring you run the risk of breaking your piston. The spring shown in the picture is barely stretched. You can safely stretch yours another inch or two. (The increase in range from the amount I stretched the spring shown was small, only like 10 feet)
Image 10; Stretched Spring
After putting the spring back in the piston, push the red spacer down, compressing the spring, and turn the spacer in the slots, so that the spring is held on
Image 11; Cleaned Spacer in Piston
Although it isn't necessary, I find it helpful to put a straw inside the white inner tube before epoxying it to increase stability (image 12). I think its good to superglue it in there. Put the two opaque white pieces together, using the black line to help you line them up. Epoxy the two pieces together, and give them sufficient time to dry. This isn't a moving part; it holds pressure (just a clarification).
|
|
|
Image 12; Support Straw in Piston's Inner Tube |
Image 13; Epoxied Piston |
(Wait at least a day so the epoxy is dry.)
Put the vinyl tubing back over the piece on the end of the piston. Screw the cap over the vinyl tubing.
Place all of the parts in their correct positions (refer to image 2 if necessary). Screw the case back on.
Hopefully this mod increases your Rapid-Fire 20's range significantly. One of the highly possible negative consequences of this mod is that your gun's pressure chamber will not be big enough to hold enough air to fully empty the clip. I am currently working on a backpack to hold lots of air. (Hint: never use PVC cement with jelly-like consistency). I also hope to create an improved turret for more accurate shots, and hopefully better range. On nerfHQ my name is Uriel. Look for my next modifications there.
Document completed April 2nd, 2004