After the last update I took a break from The Fin to cool off and think of ways to fix the issues it had. Over the past month I have slowly got back to working on it and I have finally made it to a point where I consider it revision 1.1! In the coming weeks I will be printing another version of the blaster and working out the new kinks in the design. This new revision feels better and not as rushed as the previous one… I am pretty confident in the changes and I am excited to see them realized.
In my previous update I laid out the core issues I was experiencing with the initial design. The main issues were:
- Bad airseal
- Poor, unreliable trigger design
- Fragile reload mechanism
- Difficult assembly
The first issue was a rather simple one to fix. In the original design the pusher used an o-ring to create a seal with the barrel. This seal however also encapsulated multiple 3d printed parts that did not sit 100% flush with each other and the barrel. This would result in a small gap but the o-ring where air would easily escape from during firing. If the user didn’t pull the pump grip forward enough this leak would be bad enough that darts wouldn’t even leave the barrel of the blaster… To fix this I merged the two semi-circles that formed the back of the barrel-way into one piece. This new feature solely exists on the Magwell Top. If the airseal remains poor I will remove this feature altogether and just have the Turn-Around act as the entire barrel-to-seal-way.
The craptastic trigger was by far the hardest issue to overcome. In the end I realized that the horizontal movement of the Trigger Catch against the Plunger Catch was flawed. A rotational force that applied downward pressure on the Plunger Catch made more sense. In order to achieve this the entire Catch system was remade. The initial new redesign used the same offset trigger mechanism from the original. It started not making sense to have multiple off-axis forces in the design just to keep the core form factor of the blaster the same. In the end I made the tough decision to redesign the entire body of the blaster to allow for the trigger to be single axis. In other words, now the blaster's trigger runs straight through the center of the blaster, removing all other off-axis forces from the trigger pull. Below is a simple gif showing the new trigger mechanism in operation.
I know what you are thinking, yes it does cut right through the air path for the turn around. There is a bridge in the air path already to prevent darts from falling into the turn around. This design just expands that bridge a bit to accommodate a threaded rod running through the middle of it! I will have to test this to see the effects this has on airflow but I am optimistic that it has none. I will update this in the future after I have tested it in person.
On the fragility of the reload mechanism I have incorporated two things into my design. The first is a beefed up Ram Brace. Instead of being a simple bracket I added a lofted bit to help alleviate some of the force applied to the pusher. This new lofted area also allows for an additional screw to be added to help spread some force out to the pusher. This new design does make this part significantly more complicated but I feel that its added complexity is necessary for the proper functionality of the blaster.
The other new piece in the design is the addition of threaded inserts for any component that involves the threaded rods. Before I was having issues on the rods stripping out of the 3D printed parts. This was the main failure on the last working v1.03 blaster. Adding these parts does increase the cost and difficulty in assembly of the blaster but I feel it is a necessary complexity. I am currently looking into alternative designs that utilize captive nuts instead of the heat set inserts. There are also heat set inserts on the new trigger design as well.
Lastly, and one of the most annoying issues to the end user… the difficulty in assembly… Now I can’t entirely speak for this currently as I haven’t built a new blaster yet BUT I do have some thoughts on how this has improved. With the new trigger design the threaded rod is now significantly easier to deal with during the assembly process. Same goes for the reload rod with the addition of the heat set inserts. I will have a better idea on the ease of assembly in the future.
At the moment I don’t have any IRL photos to show but here are some CAD comparisons to my original design. The new linear trigger design forced the body a bit taller… The Fin is still the same length however.
I have also incorporated the first alternative design piece! With the new taller body and the lack of left side trigger threaded rod there is some new empty space that could be covered up. Sadly the right side does not share in this some one half of the inner mechanisms will be exposed. Below is the Shroud vs No Shroud alt designs. I will have more alt pieces in the future.
I will update this github page with any new info I have in the future. But for now, See you Space Cowboy
The Fin: A Reflection, and old info
PRINT AT YOUR OWN RISK. AS OF V1.03 THIS BLASTER IS FUNCTIONAL BUT VERY FINICKY AND HARD TO BUILD. YOU HAVE BEEN WARNED
The Fin is a straight Talon mag fed pump action springer in a small compact frame. Coming in at around 15in (390mm) long! The blaster packs an Espyr spring volume with a side mounted mag to help keep the blaster compact (this is also how I came up with the name for it). Two threaded rods make up the trigger mechanism and the reload action. The rods are hidden behind the center shroud for aesthetics. The blaster utilizes a turn-around much like the Lynx or SLAB to transfer backward airflow into dart throwing power. Picatinny rails or just some iron sights are planned, I just wanted to get one printed to work out any bugs before more design work.
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…
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. Brief scribble below shows this:
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.
- 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.
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?
Here is a imgur link to some renders of the blaster: OLD
Changes
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02-03-2022: The Fin Redone
- Added re-reflection
- Updated Parts
- There are many... 18 of the 26 parts in the blaster were updated. Most of the body has been updated to accommodate the new trigger design. Instead of listing all of the changed parts its easier to list what hasn't changed... Grip Right, Mag Release, Plunger Cap, Plunger Catch, Plunger Catch Spacer, Plunger Catch Cylinder, Plunger Shaft, and Short Plunger Cup.
- New Parts
- Grip Bracket
- This is a combo piece of the Reload Block and Pump Grip Core
- Contains base for the new trigger system
- Trigger Catch Guide
- Instead of the Front Spacer having a built in guide for the Trigger Catch it is now a separate piece
- Trigger Actuator
- New Trigger design. Uses rotational force instead of horizontal movement to move the plunger catch
- Grip Bracket
- Removed Parts
- Pump Grip Core
- Combo'd with the Reload Block to make the Grip Bracket
- Reload Block
- Combo'd with the Pump Grip Core to make the Grip Bracket
- Turn Around Spacer
- Renamed to Logo Spacer for simplicity
- Fronter Spacer
- Merged with the Front Spacer because the trigger guide was made into a separate part: Trigger Catch Guide
- Trigger Bracket
- New trigger design didn't need the bracket anymore. Now it's linear
- Pump Grip Core
-
12-29-2022: A Reflection...
- Added Images, a reflection, whats to come
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12-21-2022: Additional Changes After Second Build (v1.03)
- Updated Parts
- Magwell Top
- Updated dart guide so the Pusher O-ring does not rub against it
- Magwell
- Updated dart guide so the Pusher O-ring does not rub against it
- Trigger Catch
- Add clearance between Trigger Catch and Front Spacer (missed in previous release, changes were present in step file though)
- Magwell Top
- Updated Parts
-
12-20-2022: Updates After Second Build (v1.02)
- Updated Parts
- Grip Core
- Implement new trigger spring design
- Grip Core Plate
- Implement new trigger spring design
- Pusher
- New keyway design
- Turn Around
- Update slot for new keyway design on Pusher
- Turn Around Spacer
- Update slot for new keyway design on Pusher
- Update clearance for Pump Grip
- Magwell
- Update slot for new keyway design on Pusher
- Magwell Top
- Update slot for new keyway design on Pusher
- Center Block
- Update clearance for Pump Grip
- Pump Grip Core
- Add cutaway to give access to screws attaching Reload Block to Plunger Catch Cylinder (Makes assembly easier)
- Reload Block
- Add clearance between Reload Block and Front Spacer
- Front Spacer
- Add clearance between Front Spacer, Reload Block, and Plunger Cylinder Catch
- Grip Core
- New Parts
- Plunger Catch - Medium
- Keyway in the Plunger Catch cut in half
- Use if your tigger is too hard to pull because of the compressed spring force on the Plunger Catch
- Plunger Catch - Medium
- Updated Parts
-
12-15-2022: Huge Design and Clearance update.
- Updated Parts (v1.01)
- Center Block
- Formerly Plunger Lock Block
- Updated screw holes, support bar, and barrel clearance
- Added chamfer for easy plunger tube insertion
- Added clearance for Pump Grip
- Front Spacer
- Updated support bar and barrel clearance
- Updated clearance for trigger catch
- Fronter Spacer
- Updated support bar and barrel clearance
- Grip Core
- Decreased internal support structure to save plastic
- Updated screw hole clearance
- Grip Core Plate
- Added clearance between Grip Core and Grip Core Plate
- Added support structure to keep trigger way square
- Updated screw hole clearance
- Grip Left
- Updated screw hole clearance
- Updated Google Drive file link
- Grip Right
- Updated screw hole clearance
- Updated Google Drive file link
- Mag Release
- Added clearance between Mag Release, Magwell, and Magazine
- Updated screw hole clearance
- Magwell
- Added clearance for Magazine
- Adjusted Trigger Bracket clearance
- Updated screw hole clearance
- Magwell Top
- Added features to make part easier to print
- Removed part of bracket that interfered with Turn Around
- Updated screw support structure between Magwell Top and Turn Around
- Updated clearance for Magazine lips
- Updated clearance for screw holes and Pusher
- Nose
- Updated support bar and barrel clearance
- Plunger Catch
- Formerly Plunger Catch Release
- Redesigned for new square Plunger Shaft
- Plunger Catch Cylinder
- Formerly Plunger Cap Cylinder
- Added clearance for new Plunger Shaft
- Updated screw hole clearance
- Pump Grip
- Removed some structure to make clearance for screw heads off of the Center Block
- Updated screw holes and support bar clearance
- Updated Google Drive file link
- Pump Grip Core
- Removed some extra structure to save plastic
- Updated screw holes and support bar clearance
- Pusher
- Added clearance between Pusher, Magwell, and Magwell Top
- Updated screw hole clearance
- Ram Bracket
- Moved screw head cut-out to accommodate new screw support structure on the Magwell Top and Turn Around
- Updated screw hole clearance
- Reload Block
- Formerly Plunger Cap Block
- Added clearance for Pump Grip and Spacers
- Updated screw hole clearance
- Short Plunger Cup
- Modified part to accommodate new square Plunger Shaft
- Added internal structure to support new square Plunger Shaft
- Updated screw hole clearance
- Trigger Catch
- Updated threaded rod hole size
- Modified ramp to accommodate new Plunger Catch
- Turn Around
- Removed O-Rings from plunger tube and barrel well
- Updated screw support structure between Magwell Top and Turn Around
- Adjusted Trigger Bracket and Pusher clearance
- Updated screw holes, support bar, threaded rod, and barrel clearance
- Turn Around Spacer
- Updated support bar, threaded rod, and barrel clearance
- Adjusted Pusher clearance
- Center Block
- New Parts
- Plunger Cap
- Removed shaft from Short Plunger
- Added structure to attach Plunger Shaft
- Changed 3 1/2 inch machine screw to 2 inch, Still #10-32
- Adjusted O-ring clearance
- Plunger Shaft
- New square shaft and key
- Plunger Cap
- Removed Parts
- Short Plunger
- Split into Plunger Cap and Plunger Shaft
- Old design did not withstand the forces of a compressed K25 spring
- Short Plunger
- Updated Parts (v1.01)
-
12-05-2022: Added drill stencil STL files for support bars
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12-04-2022: Initial Release (v1.00)