- You're dealing with a lot of force, so 2x4's are the minimum size board I would use.
- The force is being applied in different directions, so you have to account for the different pulls and pushes
- Every bike size is different, so there's not a one size fits all design, so I will not give measurements, but rather show you the techniques and components that I used to make a working human powered grain mill.
- Grainmaker Mill - $700 - we chose the model no. 99. So far it has performed spectacularly and is well worth the ~$700 price tag. Though any mill with a V-belt wheel drive should work.
- Sprocket - $4 - The most difficult piece to figure out of the whole setup. The problem is I could not find anyone who makes a sprocket that fits a standard bicycle chain and that will connect to a 5/8" keyed shaft.
- Old bicycle rear wheel sprocket - free or find an old back tire at a yard sale. You will have to take it a part and get the sprocket off. Weld this onto the sprocket that you buy above. If you don't have a welder, have a friend weld it like I did. It takes about 10 minutes to get the sprockets lined up just right, but this has to be precise. If it's not, your chain may fall off of the sprocket.
- 5/8" keyed shaft - $20 - This is used to drive your V-belt pulley
- V-belt pulley - $30 - This is used to drive your grain mill wheel
- V-belt - $10 - I used one off of an old lawnmower.
- A bicycle chain (in addition to the bicycle - that is you will have 2 chains) - $6
- 5/8" Bore Diameter Pillow blocks (2) - $24 - Used to hold the 5/8" keyed shaft.
- Bicycle stand - This lifts the rear wheel off the ground and keeps the bike and mill from shifting left or right. I found mine at a yard sale, but you can get a cheaper one for $20.
- 2x4's (3 to 5) - $8-12 worth. I use them all over for bracing.
- Quite a few screws...put one in if you feel any give
- A multi-speed bicycle: free to a couple of hundred dollars. I'm using Holly's bike.
|Top down view showing placement of 2x4's to prevent side to side forces. Notice how they attach to the bike stand.|
|You're going for something that looks like this.|
|Pillow blocks, keyed shaft, sprocket, chain, v-belt pulley all working together to drive the mills wheel.|
|If you look closely, you can see the welds that connect the industrial sprocket to that of the old bicycle sprocket. Your bike chain goes on the old bicycle sprocket. Finding this trick was the most difficult part of the design.|
|Here's another view. Notice the notch for the chain so it doesn't rub.|
|Front to back, notice the braces that connect to the bike stand. They keep it from shifting side to side.|
|Notice notches in 2x4 to cradle the bike stand cross bar. This is an important cut, don't cut your 2x4 too short - this adds stability in the side-to-side direction. Also notice the vertical support that touches the floor.|