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Gunblade build: Struggling with CAD

So, I had a cardboard model that looked pretty good but made no sense mechanically. There are several things that happen with the gunblade when it transforms from sword to gun in the game:

  • The blade moves back to the handle and gets somehow stored
  • The decoration elements between the handle and the blade extend, becoming twice the length, and rotate by 180 degrees
  • The handle rotates by about 45 degrees so that it looks more like a gun handle in an angle that makes sense when you want to fire a gun
  • This also has the effect of revealing that the hole in the part above the handle is the trigger

I will not get into the crazy details that make the gun look like an actual gun from the front as that clearly takes advantage of CGI trickery and is probably impossible to implement in a model that actually transforms. There are some pretty great props out there of either the gun form or the sword form though.

CAD model of Lightning's gunblade, both forms, textures only vaguely similar, positioning looks okay but connections are a little off In the CAD model, you can see both forms and how they correlate to each other. You can already tell I did not get the part between the handle and the moving decoration elements right. I also failed to make correct joints. I actually managed to make an animation with a moving blade but it was always off somehow. CAD turned out to be a difficult tool for a process where you want to find a missing part - it is made for people who already know all the parts and think about assembly. Also, it took me quite a while to figure out how to work with vector graphics imports in Fusion; it's okay though once you get it.

While I had a hard time and was not really satisfied in the end, I got some ideas and insights from the CAD modeling process.

  • There is a part that is mostly hidden in sword form and attached to the blade that will then pull the blade back and become visible. This part is super important and can actually be seen in the game. I copied its form from someone who made an animation of the original transform. It turned out to match really well. You can see it in the following picture.
  • There actually is some kind of base, supposedly the magazine for the gun, below the decoration objects. As I later figured out, it actually becomes visible in the game and is visible in the gun form. So I can probably get away with building a same-colored structure that holds all my parts.
  • I am thinking of having a notch in that base that the decoration objects can slide in. That will be difficult to make as all those parts will be rather thin. You can see the groove in the following picture, too.
  • A mechanic that I really like and probably will not be too hard to make is to align the rotating blade thing with the trigger such that the rotating blade holder will rotate the trigger by pushing it. That way the handle can reach its gun form position "automatically".

Another view of the CAD model. The aforementioned groove is visible. With those ideas, I went back to the cardboard model and tried to make the two new parts. I also wanted to figure out the axes and attachment points - which, ironically, was a main reason why I started to use CAD: to simulate the movements. I gave up on that. Figuring out how to make movable joints that actually work and making adjustments to already assembled parts was just too tedious in Fusion 360. It's just not the right tool for the job. It did however give me the feeling that what I wanted to do was actually possible.


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