I was in the mood for a simple project, while figuring out how to use the new laser cutter and engraver. This project to make rotary table extensions was buried in my database of possible projects. The source is eversole.
The extenders are just aluminum bars with holes appropriately drilled. The tapped holes in each bar provide for the use of strap clamps or other work holding devices. These bars were made from scrap 1/4" thick aluminum bar stock that was less than 1" wide. The bar was cut into two pieces approximately 2 1/2" long. While holding the two bars in the mill all four edges were squared up. The two bars at this stage are seen below.
The bars were painted with Dykem and marked out. The centerline was marked at 27/64" with the new height gauge. The four holes were marked from one end in 1/2" intervals. The bars marked for drilling are shown below.
A bar was set on parallels in the milling table vise and the end and center were located. This drilling operation turned out to be my first use of the newly installed DRO. The table was moved to 1/2" and the first hole was center drilled. Further movement along the x-axis and the other three holes were started. The center drill was swapped for a #21 drill and the three holes at 1/2", 1 1/2", and 2" were drilled. Moving to the hole at 1", a 7/32" drill was used to drill a through hole for a #10 screw. This hole was countersunk to about 0.95" to fit the screws on hand. Finally, a few threads were started with the 10-32 tap in the mill's drill chuck in the other three holes. The second bar was drilled the same.
The DRO made this so much simpler and quicker as so many fewer changes of tooling were required, as I was now confident of my ability to accurately return the spindle to a previous location.
Tapping was finished holding the bars in the vise. The holes were all deburred as needed. The final step in this project was prepping the short screws. Two screws were cut off so that they didn't bottom out when used in the T-slots of the rotary table. The extension bars and their screws are seen in the first photo below. The last photo shows how the extension bars might be used to hold a part on the rotary table.
