This is a parametric 2 disk cycloidal gear drive that I have designed in Fusion 360. The model allows you to change 9 different parameters to customize a cycloidal gear drive. The model has joints already added to it, so you can view the animation when changes are made. I would recommend adding a clearance to the cycloidal disks if you plan to 3D print this. I have found that anywhere from a 0.2mm to 0.5mm offset works. Here is a list of all the parameters that can be changed in the model:
- fixed pin diameter
- gear ratio
- diameter multiplier
- cycloidal disk thickness
- eccentricity
- eccentric bearing diameter
- output pin diameter
- output pin pitch diameter
- number of output pins
Below is the parametric model as well as a YouTube video if you would like to get a more in-depth look at how to change the parameters and what they each mean.
I don't want to tear down this project, but without some thorough re-engineering this is just like most other hobby level cycloidal drives and won't be of much practical use. It works as a "technology demonstrator" to show how cycloidal drives work, but that's about it.
For designing a really useful cycloidal drive, change a few simple things:
First, use steel pins. Precision ground and hardened steel pins are a cheap mass product. You can buy bags full of them for a few cents each. It also makes sure you have two different surfaces (steel and plastic) which reduces wear.
The next step up is to add needle bearings. Start by typing in "HK0406" in your favourite Chinese shop. You get a bag of 20 of these for around USD6. These needle bearings can be used in either of two ways. You can have stationary steel pins, and put the needle bearings between the steel pins and the cycloidal disk.
Or you use needle bearings with a closed end cap and put them inside the housing. In this case the bearings are stationary and only the steel pins rotate.
If you have doubt about the necessity about these pins to need to be able to rotate, then just fix the cycloidal disk itself to a stationary object and rotate the input axle. Then you will see the outer pins rolling around the circumference of the stationary disk.
The next step up is to combine the cycloidal drive with planetary gears. For this have a look at the Nabtesco drives. Nabteco is a very big manufacturer of cycloidal gears for industrial robots.
The combination of cycloidal and planetary do a few things.
First and most important, it gets rid of the awkward small pins in big holes. Instead of an eccentric bearing in the center, you use eccentric shafts at the locations of these holes. With this you can also use ball bearings here. which increase efficiency and reduce backlash and wear. With this method you can also use a big hollow shaft. This reduces printing material and time. The hollow shaft is also useful to route cables through when this is used in robotic arms etc. With the added planetary gear you also get a 2-stage transmission and therefore a higher gear ratio.
If you want to go even further, the next step up would be to use steel stafts and "eccentric bearings". For an example, use the magic word: NA4206X3A
Thanks foe the advice. Like I stated in the video this is simply a template and I am by no means an engineer. The only useful thing in the model is the actual disks, everything else is for show. However, it can be used for practical applications the only thing is that more designing is needed. I actually recently printed out an actuator I made form these and it works pretty good. While it can't be used for more industrial purposes, it should suit my needs for a low cost cycloidal actuator.
Very cool, thanks for the explanation on the video. I've been watching James Bruton (X Robots) design a cycloidal gear using similar principles and this filled in some of the gaps of how all the dimensions work together.
can you sent my the file from de cyclodite
email jostienen@gmail.com