Making a bat that can survive 4 shells (Patreon)

Alternate title: WHY IS THIS SO HARD

If you follow the discord you may have seen that I've designed, built, and tested two complete bats in the last two weeks. I also did ton of testing and design iterations on each bat. I've been busy. Although totally awesome, the first bat had this annoying little problem of not working at all. 

It was designed to swing the front part of the bat so that if you hit the bat at all it would launch the ball. I had this vision in my mind of just giving the ball a tap off the tee and hitting a home run. I really wanted to see that IRL so badly I think it clouded my judgement a bit. There were two big risks going into this design:

The internal forces required to rapidly move the front of the bat are higher with the linkage design

The momentum of accelerating such a big mass will make the reaction forces bigger (i.e. kick)

After building it and testing it, it was clear that both of these risks joined forces to create big problems. In testing the bat snapped some very beefy welds from the reaction forces trying to accelerate that big heavy moving end. I probably could have totally avoided this entire design and build by doing more engineering analysis - in particular looking more closely at the reaction forces required for it to work. I didn't ignore the analysis, but I keep running into the issue of not knowing how the pressures in the chamber will progress vs. time which is the most key thing for computing forces and stresses. I knew the risks but convinced myself it might work and just went for it. Whoops. It was a fun build though and gave me a really cool paperweight :)

I think version 2 of bat V2 (?) is where it's at:

This is the the way I should have just designed it from the beginning. It has the following features:

Dual 0.5" (double barrel 50 cal) pistons pushing a bat shaped plate. Dual smaller pistons significantly reduces the stress in the steel body

Support for up to four shells 

Significantly better braking than V1

A muffler that actually works (I'm running it in the basement with no hearing protection and no problems). It redirects all the gas into the body of the bat.

So far it's working with one and two shells. I'm currently in the phase where I'm learning about all the things that can break and then fixing them. Aside from lots of little parts of the bat, other things that are breaking include my test stand:

And the entire bat splitting in two. After the business end of the bat slammed into the ceiling it landed on my arm. Not gonna lie that hurt. Good thing I was wearing a helmet.

Things are getting there though! Given the totally insane forces, I am wondering if this bat will max out at 3 shells without breaking and do 4 shells only once. I'll be doing my darndest to make 4 shells work though, we'll find out soon.

Thanks everyone for supporting these projects. As I mentioned before, I'm putting all the patreon proceeds towards getting a high speed camera. Unfortunately it isn't here yet but once it arrives it will make projects like this so much more interesting for viewers like you. It will also make things a lot easier for me since I can see what is actually going on. Thank you!