I'm new to metalwork, and certainly new to cutting a thread on a rod, and need some help please. I am building a Radio Antenna to the design attached. The design calls for a thread to be cut on the bottom of three aluminium rods.

I have two questions, and the first is this:

Q: The internal thread on the Stud Mound into which the 'Driven Element' rod must screw is 3/8". ( https://www.thunderpole.co.uk/mounti...tud-mount.html )

The attached design appears to call for 10mm diameter Aluminium Rod. But I can also buy 9.52mm (3/8") diameter Aluminium Rod. 3/8" equates to 9.525 mm, not 10 mm. Should I buy 10mm diameter rod, as called for in the design, or 9.52mm (3/8") diameter? I am assuming that 3/8" is the outside diameter of the thread, and I don't have a lathe to reduce the diameter before cutting the thread.

I don't want to cast doubt on the obviously well-drawn plan, but logic suggests that I should cut the thread on 9.52mm diameter rod for all three rods, which won't require any preparation or reduction of diameter before cutting the thread.

Second Question:

Please forgive the dumb question - this is all very new to me - but 'measure twice and buy once' is good advice. I vaguely remember (55 years ago) being shown how to cut a thread in a school metalwork lesson.... and will need to buy the necessary die and hand tool from ebay! But what die should I be buying? Just a 3/8" thread die? Or do I need to be more specific?

Thanks in advance... both for reading, and hopefully for answering....

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