Intro: 3D Printed 3-Axis Gimbal for Drone
Concurrently with receiving the printer I was building a TBS Discovery multirotor platform for aerial photography use and had the desire for a 3-axis gimbal. Buying an entire 3-axis gimbal was out of my budget, but I did have three gimbal motors available from my earlier builds and three axis gimbal controllers had finally come down to a price I could afford.
I searched around the internet for 3D printable 3-axis gimbal designs, but to my dismay I did not find anything I liked. For one, there were few gimbal designs out there to start with. Most of them were just 2-axis and involved clunky and crude looking parts. They were also in majority designed for GoPros, while I have a Xioami Yi. Taking all this into consideration, I decided to design a 3D printable 3-axis gimbal myself. A challenge for sure, but it gave me the power to design a gimbal I liked, with the characteristics I wanted.
Step 1: Finding Inspiration
Before settling in on a basic design, I needed to do some research. As this gimbal would be going on a multirotor, I wanted it to be as compact and light weight as possible. Some commercial gimbals that do this well are the FeiyuTech mini 3D and SteadyGim3. They both use arms that are very thin seem to do nothing more than hold the motors in place. They also hold the camera with as little material as possible, overall making these gimbals only about the size as the camera and three motors together.
I also sketched out some basic arm shapes and profiles, the objective being to have things be as minimalistic, but strong as possible. I settled for arms with two hard bend points rather than a gentle curve, and a motor housing similar to that on the SteadyGim3.
Step 2: Designing in CAD
As this is a 3D printing project, a large amount of time goes into designing all the parts in CAD. CAD, while absolutely necessary for designing parts to be 3D printed, is also immensely useful for determining how individual parts will act together. With an assembled model in virtual space the maximum movements and adjustability of the gimbal can be tested. Errors in the design can also be caught before expending the effort to make the physical product.
I roughed out a design based on what I wanted in a gimbal, as well as what I found the commercial gimbals did well. I tried to keep things as compact as possible to save space and weight when mounted on an airframe. I also made sure to have adjustment points on each axis so that the gimbal can be balanced later. Another thing I made sure of was to keep every part of the design 3D printer friendly. Having parts that do not print well would make this 3D printed gimbal pointless.
Step 3: Printing a Rough Design
When designing, there is only so much you can predict before actually physically making the product. One of the things you can not easily determine (precisely anyhow), is the balance point of all three axis. Camera gimbals need to be balanced on each axis or else the motors will be continuously fighting over the torque of an imbalanced load. A imbalanced gimbal, if it even works, will not run very smooth and will be inefficient.
The balance point determines the necessary arm lengths. If the balance point is known, the excess arm length can be removed which will reduce the overall size and weight of the gimbal. As a result, before continuing the CAD design I printed rough designs of the pitch, roll, and yaw assemblies. My initial design was extra long at the adjustment points to accommodate the range of possibilities of where the balance point was located. With these first parts printed, I balanced the gimbal on each axis and updated the design from there. This was also a good time to double check if any bolt holes are out of alignment or needed to be enlarged.
Step 4: Updating the Design
After finding the balance point and identifying any errors on the rough printed design, I finalized the design in CAD. Using the results from balancing the rough design, I shortened up the arms to make the whole design more compact and neat. I also added the vibration dampening system with hooks so the gimbal can be mounted on a rail system. Although this gimbal is intended for a multirotor platform, the rail system will allow it to be easily moved to a handheld or any other system.
Step 5: Printing and Tuning
Next the updated design is fully printed and assembled. I have a small wooden stand that I built to hold some of my past gimbals that I can use to tune the new gimbal without attaching it to the multirotor. The stand allows me to adjust PID values and then pick up and walk around with the gimbal to test it.
Tuning the gimbal is another story. The board I am using is a micro Storm32 three axis brushless gimbal controller. It is fairly simple to setup, but if you have no experience tuning gimbals and PIDs it will take some time to fully tune. Luckily there are dozens of well written tuning guides online for your benefit.
Step 6: Finishing the Build
After a full PID tuning and basic testing, the gimbal is about finished. Attach it to your platform of choice and go. I mounted the gimbal to the rails on my TBS Discovery and was ready to film. Depending on the platform the gimbal is mounted to, there may still be some fiddling and experimentation with PIDs and the vibration dampening balls, but overall the gimbal is ready for use.
Step 7: Parting It All Out
Here are all the parts of the gimbal laid out for assembly. It is a little technique I learned from Adam Savage called knolling. Besides creating a nice picture, it is quite therapeutic and relaxing to lay out all the parts before a build. It also makes finding the right part easier during assembly.
This gimbal currently contains 23 printed parts and everything can be printed within an afternoon. Altogether the assembled gimbal weighs 233g with the Xiaomi Yi and 157g without.
Step 8: Performance
Here's some test footage from the finished product. In windy conditions there is some shakiness in the footage so some tweaking is still required, but overall the footage is really stable and smooth.
It is really incredible that such a high level of performance can be had out of a 3D printed design. Not to mention you are free to make and modify the gimbal in any way you like.
If you want to download and print the gimbal featured in this article, check it out on Thingiverse. It is thing number 1612223. You can also find more information about this project on the FliteTest forum, my forum name is Snarls.
Thank you for reading this instructable! This is my first one so let me know what you think and if I should do more!