Guide to Building Cam-Assisted Four Bar Flippers

As promised, I finally have the measurements I need to post a guide on the design and operation of cam-assisted four bar flipper weapons, such as the one used in X-Contamination. This style of weapon has several unique advantages, most notably the lack of any gearing whatsoever and a potential 200% increase in lifting capability over standard four bar lifters.


This CAD assembly is a little off, so don't try to use it as an exact model. I'll be correcting it over the next few days. What's important to see here is the bars present: Front, Rear, Top, and two smaller 'Drive' bars. To drive the arm you just fit the motor's output shaft into a keyed hole on the rightmost drive bar. The particularly nice thing about how this works is you don't need to reverse motor direction to go through a full cycle (raise & lower) of the arm. In this particular assembly, the rightmost drive shaft would rotate clockwise with respect to the hole in the large plate of metal.

The purpose of the drive bars is twofold: the first is to convert a rotational motion to a linear motion, pushing and pulling the rear bar (the main work during flipping). The second and vitally important function belongs only to the rightmost of the two drive bars, and that is to directly push on the front bar for the first few degrees of the motor's rotation. This requires it to have a cam shape, which is not shown here. All you have to do to make the appropriate shape is find out how the radius of the cam varies with relation to a single point on the front bar and the center of the drive shaft (to keep both in contact). This is what gives this four-bar design a 200+ % boost in lifting capacity compared to more conventional designs.

Finally, to make this auto-reset, build one of these:
https://battlebots.forumotion.com/design-f2/auto-reset-flipper-lifter-circuit-t45.htm
Mount it anywhere in relation to one of the bars so that the switch is pressed when the arm is in the "down" position on a strip of springy material (trust me, this makes things much easier on you).

Okay, I've finally got something up. Enjoy.