Turn an Aluminum Knob

I needed a knob with 1/4-20 threads for the band saw circle cutting jig I was building. The fastest option was turning one from 3/4" aluminum round stock. The following instructions assume basic knowledge of metal lathes.

Materials:

• 3/4 inch aluminum round stock or other material to make the knob from (enough to hold in the lathe and cut a 1 inch long knob from)

Tools:

• Metal lathe

• Drill chuck that fits the lathe

• Right-hand cutter

• left-hand cutter

• #7 drill bit

• Center drill

• 1/4-20 tap and handle

• Knurling tool with your favorite pattern

• Parting tool

Calculate the next smallest diameter to work with your knurling tool. I just took off enough material to clean the surface as perfect knurls were not important. Turn down the diameter along a 1.25 inch length of the rod using the right-hand cutter. All the turning and drilling was done at about 1500rpm.

Using the left-hand cutter, turn the face to achieve a clean surface.

Use the center drill on the end of the rod to create a start mark for the next drilling step.

Chuck the #7 drill bit and drill to a depth of 3/4 inch. Adding some lubricant to the bit will help with chip removal.

Chuck the 1/4-20 tap in the tap handle and add a little lubricant to the tap threads to prevent sticking. Use a center in the tailstock to align the rear of the tap handle with the drilled hole (I used a center drill). Tap the hole until it bottoms out.

Reduce the diameter at the base of the knob for about 1/4 inch along the rod using the right-hand tool. The dimensions are a visual choice, so you decide. Leave enough material to support the threads.

Use the knurling tool to apply some grip to the knob. I textured a little over 3/4 of an inch. (about 200rpm)

Cut off the knob using the parting tool at a little over an inch.

Secure the knob in the lathe with the parted face out. Take a finishing pass on the face using the left-hand tool. Round the edge using a file or other tool.