Step 1: Parts and Tools
- 1 length of PVC pipe (I used 6" of 2" diameter pipe)
- 1 PVC flat end cap
- 1 PVC male screw adapter
- 1 PVC female screw cap
- PVC cement (I didn't use any, but I would next time)
- 1 threaded rod (I used 5/16"-18 threads)
- 3 nylon locking nuts (5/16"-18)
- 1 wing nut (5/16"-18)
- 1 coupling nut (5/16"-18)
- 1 hex bolt (5/16"-18, make sure the bolt is only threaded about halfway)
- Balls for the mill (ideally lead balls)
- 5/16" drill bit (or whatever the diameter of your threaded rod is)
- Wrench for the locking nuts
- Vise-Grips / locking pliers
- Small rag
Step 2: Cut the PVC and Threaded Rod
Then cut the threaded rod with the hacksaw based on the length of your pipe. It will need to be about 3 inches longer than the pipe, leaving room for the adapter, screw cap, and wing nut on one end, and the cap, nut, and half of the coupling nut on the other end.
Step 3: Drill the Caps
Step 4: Thread the Nuts Onto the Rod
Start one of the nylon locking nuts onto the end of the rod, and use the wrench to work it down the length of the rod. You'll want to go down just far enough so that you can fit the screw cap over it and have just enough room for the wing nut to tighten over the cap.
Start another nylon locking nut on the opposite end of the rod. This nut will need to go down a bit farther, so that the flat cap will fit over it, and so that there's enough rod left to thread a second locking nut and half of the coupling nut.
Step 5: Assemble the Shank End
Note: I changed my design after the initial build and I neglected to retake the pictures. The images are slightly inaccurate and show the screw cap instead of the flat cap on the shank end of the mill, but just pretend it's the flat cap.
Feed the long end of the threaded rod through the hole in the flat cap.
Using the same technique as in the previous step, thread a second nylon locking nut over the cap and tighten it down to hold it in place. Then thread half of the coupling nut onto the remaining portion of the rod.
Step 6: Create the Shank
First, install the hex bolt into the coupling nut with a wrench until it's very tight. All the threads should be inside the coupling nut, with just the bare rod of the bolt exposed.
Then clamp down the mill and use the hacksaw to cut off the hex head of the bolt, leaving behind the smooth rod of the bolt.
Congratulations, you made a shank! (But not the kind you kill people with in prison.)
Step 7: Assemble the Body
Slide your PVC pipe into the cap on the shank end. If you choose to use cement, apply it here.
Then slide the male screw adapter onto the other end of the pipe. (This is your second chance to use the cement and smell those fumes.)
Step 8: Assemble the Mouth End
Screw the female screw cap onto the male screw adapter until it butts up against the locking nut on the rod.
Then thread the wing nut onto the remaining length of rod and tighten it down to hold the screw cap in place.
Step 9: Use It!
First, remove the wing nut on the mouth end, then unscrew the cap. Load up the mill with some balls and fill it with your material to be milled.
Note: Don't fill up the mill all the way, or it won't have any room to do it's job! Use plenty of balls and leave plenty of room for tumblin'.
Screw the cap back on and reinstall the wing nut, fit it to your motor of choice, and let it grind!
Step 10: Improvements
- Use a wider and shorter pipe.
- Use PVC cement for a better seal and stronger hold.
- Find some actual lead balls to do the milling.
- Implement some sort of screen in the mouth to prevent the balls from falling out when emptying the mill.
- Create a mount so the mill can be stationed on a table while spinning.