Photo 29 — This set of large drill bits was purchased at a flea market for $25. It may have only been used once, but they were the right tool for this task to drill out at 7/8 inch hole starting with the smallest at 9/16.
Photo 30 — Side-by-side comparison of the tail light bracket. Left is the original steel bracket that was mounted on the driver's side chassis. Center is the wooden pattern used to cast the right side bracket, and right is the completed machine brass bracket.
Slitting is one more task that a milling head can perform and should be done in light passes. For the final step on our bracket project, we used a metal saw on a special mandrel to slit a groove into the brass casting where the bolt passes through to tighten the tail light's stanchion. We used the same process to make a groove on the face of a high head brass bolt. Photo 31 shows where we started. The original bracket which was riveted to the driver's side of the chassis. A wooden pattern was carved to provide a symmetrically opposite bracket for the passenger side and a rough casting was made from this pattern. And lastly, the finished bracket. And Photo 32 shows the completed bracket on the chassis frame.
Photo 31 — A slitting saw was mounted onto a special mandrel in the milling head and a slit is cut into the brass casting.
Photo 32 — The face of this special high head 1/4-20 brass bolt required a slit across the face. The bolt was held in a deep socket on the vise mounted on the cross feed table and moved across the saw's face in small increments.
Photo 33 — The completed brass bracket is riveted to the chassis. This is a good example where milling and precision drilling for the rivets would effect the positioning of the bracket on the frame.
The next series of photos show a turn signal indicator being machined from solid aluminum bar stock. First, in Photo 34, we determine the appropriate size we want our finished block to be, relative to the size of the two light emitting diodes we will be using. Next, we squared the block using a milling bit (Photos 35 — 37). A 3/8 milling bit was selected even though a larger bit could have performed the job in fewer passes. This was because the same 3/8 bit was needed for our next step, hogging out the middle. The aluminum block was flipped over and many passes of the 3/8 milling bit milled out the middle section (Photo 38). Afterwards, a smaller 3/16 milling bit was used to clean up the straight edges and make crisp corners. The completed indicator project is at Photo 39.
Photo 34 — Solid block of aluminum is shown to fit small Light Emitting Diodes (LED's) for a turn signal display. To accept the LED's, the alum block must be hollowed using milling bits.
Photo 35 — The first step after the aluminum block was cut was to square up the block. Shown is the block held in a vise on the cross table and the milling bit lowered to the appropriate height.