I decided to sit down yesterday and start cadding a brand new version of the part sorter. I had a few requirements for the design process.
- Easily Scalable and Stackable
- Small Size
- Low Cost
I had a few ideas to do this the first was to use lazy susan mounted to a gobilda frame and attached the gobilda frames in the center of the lazy susan and have a stepper motor in the center turning a gear pattern attached to the lazy susan. The biggest problem though was that I couldn’t line up the gobilda pattern in a way that gave me enough mounting space. I am currently using 6-inch lazy susans if I went with bigger ones it would be pretty easy but remember we want small size and cheap.
So I moved onto just using lazy susans, laser cut parts, and gorail for support. This was the design I ended on. The laser-cut parts provide me flexibility with where I can mount things like stepper motors and gorail beams. I was able to CAD a four-layer part sorter using this concept and it should be pretty solid.
One problem I ran into was creating the gear pattern. Sure I could have just thrown a few triangles in there and did a circle pattern and call it a day, but that’s not actually what a gear tooth looks like. The most common gear is a spear gear and most of them use involuted teeth. That basically means they aren’t just triangles, the geometry of the teeth is very complex and designed so that the teeth on the two gears mesh nicely and unmesh nicely giving you very smooth movement. It also guaranteed that the teeth are in contact almost the entire time they are moving. I followed this great tutorial here to learn how to CAD these involuted teeth. I am also using a 32 pitch gear 16tooth that mounts to the stepper motors. When describing spur gears the pitch is a measure of how many teeth are present in a gear with 1-inch pitch diameter. So really pitch is just a measure of the size of the teeth. The tutorial talks about how to calculate tooth number based on the diameter and pitch of your gear.
This is the design that I might try and build at Techgarage today. It supports sorting up to 40 parts and is only 16 inches tall!
Devin Willis 