This is a payload release mechanism that I designed for use with my 680 hexacopter. This is used with a 3 position switch on your controller to allow you to carry and drop two payloads.
I had heard of people that have made or even purchased payload release mechanisms to drop cargo remotely from their drones. I did some searching on thingiverse and found a few designs. Most of the designs were single payload mechanisms. I had only found one mechanism for multiple payload drops. It looked like it could carry four payloads, but there was no description of how it was supposed to work.
My design is a dual payload drop mechanism that is based off of this design by the user flying ginger. His mechanism uses a 9G micro servo, but all I had in my spare parts box was a full size Futaba servo, so I used that. I may make a revision down the line that will use a 9G servo, but this will work for now. Below is a picture of the mechanism that I designed.
The design was done completely in OpenSCAD. The OpenSCAD file uses a couple other libraries. One of these libraries is the mock up design I did of the Futaba servo that I used. These files are included and can be placed in your OpenSCAD libraries folder.
One other part that I included an stl for is my bar mount for my custom rail setup that I use for my camera gimbal. I had some extra room toward the rear of the rails to mount this, so that is what I used. You can mount this to your drone however it suits you using the two holes in the bottom of the plate.
The only hardware I used for this is four 3mm screws and four 3mm nuts. Two attach the servo to the base plate, and the other two attach the rail mounting bracket to the base. I also used a large paperclip for making the pin connector rods. I just bent them with needle nose pliers. Bend the paper clip pieces so they hold the pins 1 to 2mm from the outer edge of the holes when the servo is in the centered position.
The claw mount as someone called it is made specifically for my drones rail mount setup which is made from some 1/2 inch aluminum tubing mounted with custom brackets. You may need a different kind of mount to fit this to your craft. If you decide to make your own mount, the holes in the base plate for the screws that hold the mounting claw are 3mm in diameter. The holes are spaced 44.75mm apart. You will need to know that if you want to design your own mount.
In order to use this mechanism, you will have to have a 3 position switch on your controller where the center position will keep a servo in its center position and switching it up or down will move the servo to it's outer limits. To load the mechanism, attach your payload to the smaller hole of one of the figure 8 rings and put your switch in either the upper or lower position. This will cause one side of the payload release to open. Stick the larger part of the figure 8 ring in the open slot and flip your switch to the other extreme position and repeat the procedure for the other side. Once loaded put the switch in the center position. This should close both release pins enough to hold both payload rings in place until the drop.
So when I originally designed this, the hole just below the servo arm was there because I was originally going to use a X shaped servo arm. That was before I decided to make my own servo arm because I needed one shorter. This eliminated the need for the hole, I just didn't remove it because I figured it would save on some weight, which is usually a concern with drones. So today I got to thinking about reducing the weight even more and decided to remove that hole and add a cutout honeycomb design to the majority of the base. I figured, not only will it reduce the weight, but it will also look cool. Below is a picture of the version 2 design. The only thing that changed was the base. All other parts, i.e. pins, rings and servo arm, have remained the same and should fit the V2 design. I added the honeycomb design library file that I used to do this. Just add honeycomb.scad to your libraries folder and you should be good to go.
Here is a short video testing the operation of the dual drop mechanism. This is testing it with my modified FlySky FS-I6 transmitter. The transmitter is modded to convert swB from a two position switch to a 3 position switch
I always welcome feedback and comments on my designs. Feel free to leave a comment in the comments section.
Have fun, fly safe and follow the rules.
I take NO responsibility for any actions you take when making and using this mechanism. You should always fly your drone in a safe manner and follow all the applicable rules for your area.