Simplified Mechanical System Part 2

Secondly we need a shaft/axle that will work for the following functions (as mentioned previously)..


1. They hold components where they need to be.  But they also need to be held in place on the shaft.
2. Shafts give various components a common rotational axis.
3. Shafts transmit motion from one component to another

Let's tackle number three first.

A D-profile shaft will allow components to spin on the shaft, as well as being able to transmit power. Also its easier to go from a store bought shaft to a d-profile, than it is to put a key slot into the shaft. 

But this still doesn't place a component somewhere along the length. 

This is where standards come in again. If your components could be a certain thickness, then maybe we can avoid making a custom shaft, a common design will do for many different setups. 

We can cut concentric slots in the axle of specified width with specific spacing, then we can make our component thickness match those measurements. 

Like this..

Then E-clips hold the components in place along the shaft. 

Kinda like this..

Simplified Mechanical System Part 1

I had an idea. 

I was talking to my brother and as I talked I was frustrated at how hard it was to build things. The biggest problem in my opinion is. Everytime I want to build something, it pretty much always involves some kind of shafts. 

Shafts have several functions: 

1. They hold components where they need to be.  But they also need to be held in place on the shaft.

2. Shafts give various components a common rotational axis. 

3. Shafts transmit motion from one component to another 

If you want to place a component on a shaft and have it perform reliably, it needs to be held in place on the shaft. If you want a component to spin smoothly, then you need a bearing placed on your shaft. The bearing needs to have the same inner diameter as the shaft's outer diameter, within a few thousandths, if not things will vibrate and wobble and all kinds of problems. Most shafts get stacked on with a different diameter for each component. Thats alot of custom machining. 

Borrow from: Wikipedia

I don't have the resources to machine custom shafts each time I have an idea, and I'm not alone in not having them.

Bearings are the next big problem. Some things need to free-spin on shafts and some things need to be engaged on the shaft. Again with each component needing a different inner and outer diameter. 

What's needed is a standard, a system. 

Kinda like the Arduino. Standard shields fit standard sockets with standard pinouts. It works for electronics, it works with Personal computers, PCI cards fit in PCI slots. Serial ATA drives plug into Serial ATA cables. Standards make building things (relatively) simple. (USB has got to be the best example Ever!) 

Then I realized. I've used skate bearings in several things. Skate bearings  are ubiquitous and standardized. Here you can get 100 for $35, $0.35 a piece! 

They have an exactly 8mm inner diameter and 22mm outer diameter, they are 7mm thick. But they don't come with any mounting help, no flange, no bearing block...

So an 8mm shaft will mesh up into a skate bearing exactly. 

Skate bearings are perfect for a simplified mechanical system...