It seems like yesterday when we first came across Jo Kerr's well-traveled '30 Ford coupe parked on the outskirts of the NSRA Street Rod Nationals in Louisville, Kentucky. What immediately grabbed our attention was so many of the unique parts it wore. A closer look revealed a cast finish so well executed that we had to track him down for the lowdown on how he created the parts. These were all signature items personally machined to work into hot rods being built at his shop, JoKerr Fabrication. Kerr tells us that there are a number of finishes that can be created when using billet aluminum, from highly polished to a sand-blasted look. However he longed to recreate a cast-style finish and that's wherein the magic lies. We finally convinced him to let us have a closer look at how the parts machined from, believe it or not, solid billet aluminum. This isn't the billet of the past as you remember; it's a whole new deal. Let's take a closer look as he creates two of his very own signature items.
When designing one of his shifters, careful consideration is taken to the ergonomics of the driver with regard to seating placement and shifter height. Typically, with the hot rods being built at his shop the shifters created are 16 inches tall. To get started a section of 1-inch-diameter T-6061 aluminum stock was cut to the exact length. Since the shaft will be tapered, a measurement is taken at 2 inches from the bottom and marked with a coating of blue machinist's dye. The dye establishes a guideline to use as a base to begin turning the taper from. Prior to securing the stock in the lathe, the top of the shifter was measured to locate the center and was then drilled with a 0.250-inch bit to establish a hole to secure it in place to the live center on the lathe. To take on the job, Kerr used a Kingston Machine Tool HQ1440 lathe and secured the base section in the three-jaw chuck while making sure both ends were secure. The tapering attachment was then set at 1/2 degree and while wearing safety glasses, 0.050 inch was removed from the surface with each gradual pass. This continued until the desired graceful taper was achieved. The shifter was then completely coated in machinist's dye, and once dried, it was removed from the lathe and set back onto the layout table.
To add some edginess to the design, a height gauge was used to scribe locations for lightning holes starting at 3/4 inch above the taper line and from there every 1 inch until 11 total holes were marked. The shifter was then moved to a first vertical mill where the base was secured in a Kurt vise. The upper section was then placed in mill clamp stands. Kerr tells us that proper setup is everything and that it's imperative the part is secured tight to ensure there is absolutely no movement or vibration during the machining. A center finder was then used to locate the center of the first hole prepared for drilling. Starting at the bottom of the shifter the first four holes were drilled using a 5/16-inch drill bit, followed by four using a ¼-inch bit, and the final three using a 3/16-inch bit. With the holes completed a ball mill was set up while still on the center of the last hole drilled. Wanting to add a groove to the left and right shifter sides, a ½-inch two-flute ball mill was used. It's important to be sure the shifter is still level in the vise before proceeding. In order to remove 0.150-inch, three passes were made removing 0.050 inch from the surface with each sweep.
1. To create a shifter, Jo Kerr starts with a 16-inch section of 1-inch round T-6061 aluminum rod. A 2-inch guideline is the applied to one end using machinist's dye to mark the start of the taper.
2. Using a Kingston Machine Tool HQ1440 lathe, the taper attachment is set at 1/2-degree starting at the top of the shifter and it is gradually worked toward the 2-inch base.
3. At this point a number of passes have been made removing 0.050 inch from the surface in each cut till the desired taper is achieved.
4. The shifter was removed from the lathe and recoated in machinist's dye. Using a height gauge it is then measured 3/4 inch above the taper line for lighting holes every inch.
5. The shifter was moved to a First vertical mill where its base was secured in a Kurt vise. The top is then secured tight in mill clamp stands to avoid any movement or vibration.
6. A center finder was used to locate the exact center of the first hole to be drilled at the base. Using a 5/16 bit, the first four holes were drilled.
7. Moving up the shifter a 1/4-inch bit was used for the next four holes followed by a 3/16 bit for the final three at the top.
8. While still on center, Kerr used a 1/2-inch two-flute ball mill to start the groove process. Three passes were made removing 0.050 inch from the surface with each sweep.
9. Secured in a bench vise, a metal burr wheel for steel was used to create the surface texture with a precise repetitive motion in each direction gliding it from left to right.
10. Finally, the finish was completed by sandblasting the part followed by a thorough cleaning with an air hose followed by brake cleaner.
11. To give you an idea of the work involved in creating his signature fuel block you can see the three stages here of how the part evolves from a solid section of T-6061 aluminum.
12. A 2-inch square by 4-inch long-block (coated with machinist's dye) is used as a base of the fuel block. A center hole is first scribed to the block bottom for the fuel inlet.
13. Using a height gauge, the mounting surface lines are scribed at 1.2 inches from the top of the block and then 0.575 inches leaving a 5/8-inch mounting band.
14. The fuel block was secured in a vise to drill a 2-inch deep inlet hole using a 7/16-inch drill bit. The hole was then tapped with a 1/4-18 pipe thread.
15. An old fitting was then installed to give the unit something to secure to the lathe. Also a small center hole was measured and shallow-drilled on the other side as a live center hole.
16. The block was then mounted to the lathe. Kerr advises great care should be taken here to properly mount the section as the square edges can easily shatter while being cut.
17. Using a facing insert tool, the process starts by making 0.100-inch cuts below the marking surface. This continues until the unit becomes completely round.
18. The cuts were then adjusted to 0.050 inch and worked till the desired diameter was reached, in this case 1.875 inches. It was then reversed and cuts were made to the top of the fuel block