Features

Here is a page of detailing many of our design features and the reason behind each choice

CNC Machined Pulley

To utilize the back wheel of the bike as one of our pulley's we chose to use a 5L V-belt.  However, in order to get the speed we needed for the spindle we needed a 5" pulley compatible with the belt we needed.  So, we CNC machined a custom pulley that met all our specifications and works perfectly!

Custom Keyway

After CNC turning our pulley, we needed a way to attach it to our spindle shaft so that we could successfully transmit torque between the belt and the spindle. We brainstormed various methods and although there were lots of feasible methods that we analyzed, we settled on doing a key and keyway. To do this we machined a round keyway in our pulley and a round keyseat in the shaft. Then we used a 0.25" round key to connect our parts. 

Aluminum Extrusion Frame

It was important that we make the lathe adjustable so that different sized workpieces and tools can be used. We also needed a base that would allow us to mount all of our components to. After lots of brainstorming we settled on using an Aluminum extrusion frame.  The frame allowed us to easily mount all of our components, line up important components, and have adjustability. The tail stock and tool rest are mounted using a series of extrusion frame nuts. This allows these components to easily slide along the extrusion when the screws are loosened and and remain stationary and rigid when they are tightened.  

Bicycle

We spend a lot of time debating whether to use a stationary bike or a regular bike with a bike trainer. We ultimately decided on using a regular bike for 2 main reasons. We wanted the rider to have adjustability when pedaling so that they could maintain a constant spindle RPM while remaining comfortable. The gears on a bike allow the rider to change the feel of the pedaling while keeping the back wheel RPM (and thus the spindle RPM) constant. Additionally, we thought it would probably be easier and cheaper to buy or borrow a bicycle than a stationary bike.  To use a regular bike we needed to buy/find a free bike trainer and swap the rear axle to a bike trainer friendly. 

Tool Rest

It was important for safety that we have a tool rest. In order to accommodate multiple tools, the tool rest would have to be height adjustable. To make the actual tool support component, we welded a 1" diameter steel rod to a piece of 1" angle iron. This created a very comfortable and strong tool rest. Then, to make it height adjustable we used a 1" inner diameter steel pipe this allowed the tool rest to slide up and down. We used a set screw with a knob in the pipe to lock the height and rotation as needed. Finally to make the tool rest adjustable in the X and Z directions, we mounted the steel pipe on the aluminum extrusion frame which gave us the desired adjustability. 

Table Fixturing

One big concern we had was how to fix the lathe to the table and minimize vibrations. Initially we were planning on bolting the aluminum extrusion frame directly to the table, however, the bolts to attach the frame to the table would limit the adjustability of the tool rest and tail stock. We were also concerned that the vibrations wouldn't be damped well because the spindle was attached to the table through multiple connections. To address this concern, we bolted the lathe to the table via our head stock, used a thin layer of foam underneath the lathe, and then clamped the rest of the lathe to the table using a 2x4 bolted to the table. After testing the lathe again, we found that this was incredibly helpful at damping vibrations while keeping the lathe adjustable.