Thread On Old Lightning Rod

1/2 inch dowel and hot glue.

Yeahbut - where's the metal content in that (other than the spike itself)? Oh, I suppose you meant a *metal* dowel.

Joe

Similar to the thread on railroad insulators?

Dave

Well, if you can make a base with an oversize socket, position the rod and pour in a little molten lead (or pewter, if you have some). It won't stick, like glue or molten sulphur might.

Let the Record show that Joe on or about Fri,

16 Oct 2009 12:56:05 -0400 did write/type or cause to appear in rec.crafts.metalworking the following: 14 mm by 1.25? Its a guess.

You could use a candle or similar to get an impression of the bolt hole, then be more precise in your guess work. If you just want to put it up for display, silicone caulk and a metal dowel (Ob metal content).

- pyotr filipivich We will drink no whiskey before its nine. It's eight fifty eight. Close enough!

Take a print with aluminum foil to measure pitch (measuring microscope or comparator are best, eyeballing with calipers or ruler less so). Measure minor diameter with calipers, pin gages, etc.

Knowing pitch and major diameter, find the range of basic diameter possibilities, and all the practical thread data, using my calculator:

If it's old enough it may not be _any_ standard thread. AFAIK the thread standards weren't established until the early 1900's; I would suspect that even up to the '30s it wouldn't have been uncommon to have nonstandard threads on such things.

If you are using Windows, gawk seems to run Richard's "thread.awk" program okay. At least it handled his examples fine. See:

Open Richard's thread.awk program in a text editor and read the first few lines of comments to learn how it is suppose to be used.

If you want a manual, instructions for using Gawk look here:

My test system is old, Windows NT4. This is command prompt stuff too (shrug).

Sorry, that should say, "knowing pitch and *minor* diameter" (measured from the inside thread).

Mmm... you sure of that Richard, this is from thread.awk beginning comments:

Not trying to nitpick, just understand how to make use of your program :)

Let me clarify. The program tells you the (range of) minor diameter(s) for a given basic size and pitch you specify. If you know only the minor diameter, you will have to try various basic sizes to interpolate the target minor diameter for a given pitch.

[The basic size (diameter) is the nominal major diameter, for which the allowed actual major diameters are slightly smaller.]

No. The thread on the spike is 14 tpi (checked it with a gauge last night).

I haven't tried it yet, but I'm wondering if the thread on the old insulators is the same as on push-broom handles, etc. I want to mount several of the old insulators with a hole bored through the wood so I can thread wires for LEDs. I think they would make cool path lights. (OK, my wife actually came up with the idea, but she doesn't read newsgroups, so I can take a little credit, can't I?)

Joe

Yeah, that's what I suspected after it didn't pass the "bolt test". This spike is a really beautifully patterned item, with a nice green patina. The inside of the socket shows signs of plating in there - I wonder if it was silver plated to increase conductivity (the plating isn't really shiny like chrome or nickel - sort of a warm tone).

Anyway, guys, thanks for the ideas. Whatever I use for mounting it will have to be easily removable - I don't want to munge up the original mounting provisions.

Joe

Thanks Richard, I added the extra info to my notes for your program.

Maybe it's lead.