In the quest to design and print a functional and robust spring, I stumbled upon a fun idea for a proof of concept. Just like in the movies, you now can attempt (and fail) to detonate stuff over and over again--or, of course, fidget / relieve stress. While I have uploaded what I, and several others, believe to be a good generally fitting model, as an added bonus, you can use Fusion to design your own to fit you own specifications. While I have put some restraints on the size limits to prevent breaking the model, you can end up making some pretty comically sized models

I think editing is pretty straightforward to most people who use fusion. Basically, edit the parameters to the values in mm you want, and the model will automatically update. After, just export your file for printing like normal. The button and spring should not and are not meant to change dimensions.

Printing Tips:

• The coil spring is the engine and key to this print. It is a good thing that I have done most of the hard work here in trying all types of different sizes, shapes, print orientations, supports, and materials (see my print coil graveyard)
  • It is my suggestion that you print the spring separately from the other parts and use either PETG or PETG+ filament. While I did have some minor success with a few versions of PLA+, PETG offers the best longevity and the smoothest operating spring
  • I also suggest the lowest layer height and full walls for this part. Basically, you want this to be as solid and dense as possible. 
  • Printing slightly hotter can increase layer adhesion as well, but may cause issues with overhang performance
  • I have uploaded a print file and a picture to show my preferred support structure and orientation for the spring. Anyone is welcome to try other avenues and report back, but I found this to be the most effective and have now successfully printed 6 detonators using these settings
  • Support removal should be done very slowly and you should be sure not to apply too much pressure on the coils
  • Another interesting option is to secondarily anneal the spring after support removal
    • I had success annealing the PETG+ spring horizontally (while stabilized) at 200F for 10-15 minutes. Longer annealing resulted in significant warping
    • If the pegs warp out of alignment some, these can be set back to parallel while the plastic is still warm
    • Anneal at your own risk and be careful with hot plastic. Don't try to anneal PLA at this temperature, but you may be able to do so at a lower temp
• The rest of the printing is relatively straightforward: 
  • Plunger - I did a high wall count to make this part decently strong and hefty. No supports on the threading and just slim supports on the under overhang. 0.12 mm layer height adds a nice heft to the part
  • Threaded Base - Highest wall count / infill on this part. I find that the the heavier weight makes the balance more enjoyable. Printing this with the bottom up allows for the large filet to not need supports. The overhang can be done with slim tree supports and any scarring is hidden when threaded in. 0.12 mm layer height results in a nice curve
    • PLA works well for both the plunger and threaded base
  • Button / Main Body - Although you can print these in PLA/PETG, I found that it was much more enjoyable making both of these out of TPU. The printing time for TPU is much longer, but I think definitely worth it
    • For the button, I suggest 0.08 mm layer height as this gives the smooth looking and feeling button. A small overhang might require slim tree supports, but not on the threading.
    • For the main body, a layer height of 0.20 mm worked well and required support for the larger inner overhang, but none on the supports or embossing

For anyone who doesn't have fusion, drop a comment for specs that you might want to see or print and I can quickly edit a version and upload an .stl.