To obtain high accuracy on a lathe, you can use a 4 Jaw Chuck. By adjusting the jaws while using a dial indicator, you can achieve better than 0.0005 of an inch runout. To better adjust the jaws, use two knobs to position the work piece. Follow the steps below to construct your knobs. I Made it at TechShop (Chandler). http://www.techshop.ws
Materials and tools:
1/2" x 8" steel rod
3" x 8" x 3/16" steel bar stock
1/8" drill bit
3/8" drill bit
1/2" drill bit
2 1/2" hole saw
Step 1: Create Drill Template
Create drill template in cad or other program. Place outer holes so hole cutter will leave less than half a hole. Glue Template to flat stock metal. I used 1/8 steel. Stack 2 pieces of metal an clamp together. Center punch through the template into the metal.
Step 2: Drill Pilot Holes
Drill a 1/8 pilot holes
Step 3: Enlarge Holes to 3/8
Enlarge outer holes using a 3/8" drill bit.
Step 4: Cut Large Hole
Set Drill to lowest speed and clamp work down. Slowly feed hole saw into work. Use cutting oil.
Step 5: Smooth Edges
Smooth sharp edges using a file or sandpaper.
Step 6: Make Shaft
Using 1/2" Metal rod, Square both ends on a milling machine. Cut the ends so they are 1.5 to 2.5 inches long.
Step 7: Attach Shaft to Knob
Enlarge center hole to 1/2 inch. push shaft in new hole and weld shaft to knob.
Step 8: Optional Step
Cut decorative step in center.