On Tue, 8 Oct 2019 06:22:29 -0700 (PDT),
wrote:

I want to permanently attach 3/8" diameter rods to 3/8" rods end-to-end and was looking for advice on the best way to accomplish this. The methods I'm considering are welding, tapping, or use of a roll pin.

The rods will only be about 3-1/2" long, and the pieces that I want to attach are 1/2" long.

Perhaps a combination of the attachment methods mentioned for this rod extension project would be warranted.

Any advice would be appreciated.

Thanks.

Darren Harris
Staten Island, New York.
Since you have a lathe then I suggest tapping. Use a roll tap AKA form
tap. These taps don't make chips so they are great for blind holes,
and they make stronger threads. You need to use a larger diameter
drill bit than for a cutting tap. Tap both part and assemble with a
set screw and red Loctite. Or tap one part and drill through the 1/2
inch part for screw clearance. Then use a socket head screw. And red
Loctite.
Eric