Hello everyone, and in particular Doom (btrettel)
I'm interested in making a pneumatic semi-auto similar to Doom's FANG. I've created a 3D printed part that mates with the standard Nerf-band clip that I'm pretty happen with. I just need to figure out which air cylinder I'll be using to feed the darts through.
I'm hoping to get exact specs or part numbers on the air cylinder that was used on FANG upgrades. I've done some reading on the original FANG post here.
It was found in the parts bin so he didn't have a part number. He also said this:
After some discussion at Spudfiles, I've already decided on one major change from prototype 1 to 2. I used a spring-return air cylinder here. The air cylinder seems to be designed to move the rod at once rather than gradually, so the spring is prestressed. To keep the force increase small, the spring doesn't travel much and has a low spring constant. And to keep the force sufficiently high to return, the spring must be rather long. All that combines to make a long air cylinder. My cylinder was about 8 or 9 inches long when it only had a 4 inch stroke.
The solution is to use a dual action air cylinder and make one side contain compressed air, with a small air chamber attached to the opening. This will still allow the spring to return all at once, but the energy can be stored in a dimension other than length.
So simply put, what have people had the most success with? The task is pretty simple but buying several air cylinders and using trial and error could be pretty expensive.
Does anyone have any opinions on these? Does anyone have any experience with others that they recommend or would suggest avoiding? Does anyone use regulators to restrict airflow to slow down the movement of the cylinder? I've considered doing that but I haven't had my hands on one yet so I don't know if the speed will be too fast anyway.
Thanks for the help. One I get enough into on this thread to make a decision I'll put together a test and get my 3D printed part and McMaster-Carr parts list up here on Nerf Haven.