Extended Hammershot hammer replacement with draw extension option

I quite liked HorsEngineer's extended hammer here, but the number of tweaks I wanted to make sort of spiralled out of control, constituting a redraw more or less from ground up, although there are a lot of similar dimensions: https://www.thingiverse.com/thing:1658576

Differences:

• Curvature of rims centres around pivot point
• More flex accommodation on shell-post cutout
• Spring-rest rod hinges closer to the pivot point, I think HorsEngineers is a little further out, which changes the interaction with springs - this might be a pro/con depending on personal views
• Hammer face extension redraw, I found the corners a little sharp without any fillets and by terminating at the edges instead of within the face. I do recognise that HorsEngineer's design makes more sense in the context of 2016 3D printing, though.
• Indexing post shortened, flush to hammer face to make it easier to align prints on bed
• Throw chamfers and fillets everywhere (Because it feels nice, stress concentrations etc., why not)
• Cut-out on stopper to match Radioactive's extended draw mod (See video below)
• Added an alternative version that extends draw even further, .f3d included in case you'd like to experiment with this.
• Cut-outs in centre of hammer - there's not much flex here, I find that the weak point is just under the hammer, that's where the most flex and breakage ends up, so it makes sense to me to cut out unnecessary mass. My prints ended up being around the same weight as the stock hammer (9g).

Radioactive's draw extension:

For context, Radioactive has a guide/product for extending the draw on your Hammershot for more oomph

To push this further, you can use the extended draw variation I uploaded, I'm not sure how much it helps, your mileage will likely vary based on your spring, overall setup, hand size, but IMO it's nice to have more options when engineering.

Note that while you could theoretically CAD the front cap yourself, it's probs more logical to just pay for the files from him or just buy the parts, they're not expensive:

• https://www.etsy.com/au/listing/1117224984/nerf-hammershot-intermediate-upgrade-kit?click_key=ab79fd2787dd79469887b8f88595993d4c0604b9%3A1117224984&click_sum=4be18c90&ref=shop_home_active_2
• https://www.etsy.com/au/listing/1128838652/nerf-hammershot-intermediate-upgrade-kit?click_key=44864fcd686ece8c9195a56a2729b4cb3e670aaa%3A1128838652&click_sum=bcdc2bd3&ref=shop_home_active_4&crt=1

My variable additional draw extension:

This hammer above adds another 8 degrees of draw, you can see that the plunger sits quite far back when fully primed.

Note that this is the specific dimension to tweak, 7.0 degrees is stock in this case, so the 8 degree extra draw version I'm running required that dimension to be bumped up to 15.0 degrees.

How much draw to add is a bit debatable though - the more we add, the easier it is for the hammer to flex, and the more uncomfortable the prime is, since it's more movement. Not to mention you have to consider how much reach your thumb has, and whether or not your spring can facilitate the extra length and air volume efficiently.

The subjectivity and nuance required for this topic is why I chose to upload the f3d - too many variables to consider, STL wouldn't have been enough.

Print strength:

I've been printing in PETG, which does tend to flex more than PLA. I also ran my earlier tests using gyroid infill, which I understand was a mistake vs cubic infill or the like to try to minimise flex.

I managed to run the hammer at:

• 2 layer walls/15% infill using stock spring
• 3 layer walls/15% infill using stock spring + spacer
• 4 layer walls/20% infill snapped under approx 7kg spring
• 6 layer walls/40% infill with 100% infill around hammer joint is currently holding up under approx 8kg spring.

PrusaSlicer allows you to manually specify more infill in specific locations that require it.

Note that messing around with the draw dimensions does give you more variables to consider in terms of leverage and thickness available for reinforcement.

Misc:

I replaced the pins with creative use of a bluetack, an M3 bolt, M3 nut and a table clamp, I've no idea what a good way of doing it would've been. Probably should've designed a jig or something.

There does seem to be a bit of flexing forwards after priming, perhaps we could reduce how lax the catch is, in order to extend the draw more.