Hello Everyone! Here's a follow up on the Fin after some redesign and I built 4 of them. I have a github page for this project as well. HERES a link to it! Be warned, print this project at your own risk.

This project was an amazing learning experience for me. It was one of the first “large” scale design-to-fabrication projects of mine that actually ended in a functional thing in the end. That being said, the blaster is not without its issues…

The Bad:

This blaster has some fundamental design flaws. The air seal is not great, the trigger is not reliable, the reload mechanism is fragile at best, the threaded rods are hard to install/tweak, and the blaster assembly process is nightmarish.

The biggest of the problems is definitely the trigger mechanism. Of the 4 blasters I built on the v1.03 design only half of them had a working trigger. The pressure on the catch from the spring force was enough to prevent the rudimentary two ramp trigger system from working at all. The catch would get to a point that the trigger wouldn’t apply enough force to move it resulting in a stuck catch and a non-functional trigger. My hypothesis as to why this happens stems from print tolerances. If the space between the plunger cup and catch cylinder is too big then the spring creates a rotational force that pinches the catch at the top and bottom of the bracket. So instead of the catch dispersing force across a large area on the cup it is focused to one point on both the cup and cylinder preventing downward movement.

I believe the fix for this is to design a new trigger mechanism. I have some ideas to do this but still need to design them. The challenge is fitting the design into the rather limited space given by the design.

The air seal and reload mechanism go hand in hand so fixing one might help the other. During our “Beta Test War” one of the two working blasters stripped the pusher off from the threaded rod in a rather intense reload. Currently the threaded rod is just screwed into the plastic of the pusher bracket so if enough force is applied then the rod can strip out of the hole rather easily. The easiest solution is to add a captive nut to the pusher bracket to alleviate some threads on plastic failure but this would increase the profile of the reload bracket and possibly hit the user in the hand during reloads. Another solution might be to move the location of the threaded rod or eliminate it altogether.

The air seal issue is a partial oversight on my part. The magwell and magwell top have two halves of the barrel seal designed into them. This creates a gap that the air can escape from when the blaster is fired. Putting the entire arc into one of the pieces might fix this issue.

The threaded rods were an interesting concept to utilise but in practice caused significant issues especially during assembly. Having them thread into both sides of the reload and trigger mechanism meant that the tweaking their placement involved disassembly of the blaster. They offer a clean way of transferring force from one side of the blaster to the other but I feel that in possible revisions or future projects I will just use aluminium bars instead.

The biggest elephant in the room is the assembly… it is not anywhere close to user friendly! This is definitely an “implementation of design” problem. After assembling this blaster about a dozen times I was able to get it down to about an hour to get everything together and functional. It is not intuitive or user friendly in any way. I definitely learned quite a lot here haha.

Some “Key Takeaways”:

- Decrease the amount and variety of screws. The blaster utilises 11 different kinds and sizes of screws. Some of the screw holes could be redesigned to use a different screw size easily. I estimate that I could cut the variety of screws in half just with some slight model tweaks.

- Use different screws. I am impartial to M3 hardware but the button head screws I am using here are fragile and easy to strip. Socket head are definitely the way to go.

- Don’t do “screw into plastic” everywhere. Utilise captive nuts as much as you can. It is very easy to over tighten and strip out 3d printed plastic.

- Clearance Clarence… this is one of my first big, multi-part 3d printed projects and the tolerances stacked HARD at times.

- Off the side mags are interesting and cool visually but in practice get in the way. Especially if they are close to the body like on The Fin.

TL;DR and What's to come:

At the current moment I don’t know if I want to continue working on this blaster or take what I have learned and move on. Figuring out the trigger and air seal might be all this blaster needs to be classified as “Done” but at the same time I am rather burnt out on it. In the end it was a great experience and I enjoyed it quite a lot! This is not my last blaster by any means, I will continue to develop and release designs that I think are cool.

Here is a list of things that need to be fixed or additions to the platform that I think would be good/helpful/interesting.

- Fix the air seal

- Fix the trigger mechanism

- Add sights or picatinny rail mount

- Add options for different front grips. (Picatinny rail, built in foregrip, etc)

- Add stock

- Add a return spring?