A well constructed lightsaber is, according to Wookiepedia , a Jedi's "single perfect weapon that he or she would keep and use for a lifetime."
If only I had such a "perfect" soldering iron that would last forever! In my experience, soldering irons are reliable enough, but far from perfect. The part of the iron that is consumed the fastest is the tip. Soldering iron tips wear down, burn up, diffuse into the solder, or something... Honestly I'm not certain where the mass of the tip goes. Intuition, and the law of conservation of mass+energy, tell me it has to go somewhere. Everything goes somewhere. Anyway, all I know for sure is that I start out with a perfect well-tinned tip like a shiny sharpened pencil, and several hours later I end up with a crusty burned-looking stub. Hence the motivation to replace the tip every now and again.
The soldering iron tips created in this instructable are made starting from 6 AWG solid copper electrical wire, and these tips are are approximately 4 mm (5/32 inch) in diameter. In this instructable, I show how to make two styles of 4mm tip, the slidey-style, and the screwy-style.
Step 1 takes a closer look at these two styles of soldering iron tips.
Step 1: A tale of two tips
If your soldering iron doesn't look like one of these, well um... I never said this instructable would cover every soldering iron under the sun. So uh... what you see here is what you get.
I call the first one "slidey-style" because the tip slides in and out of the iron. This design uses a fat screw, set into the side of the iron, to secure the tip, keeping it from sliding out while soldering.
The second, I call "screwy-style" since the tip is threaded, and it screws in and out of the soldering iron.
I definitely prefer the slidey-style, for a number of reasons: (1) The slidey-style tips are easier to adjust. (2) This system holds the tip more securely. (3) The slidey-style tips are much easier to make.
So if you're new to this soldering iron stuff, and you're wondering which style is better. The answer is the slidey-style is superior, IMHO.
Step 2: Materials and tools used in this instructable
soldering iron in want of tip replacement
several cm or inches of 6 AWG solid (not stranded) copper electrical wire.
small drill press
file, sandpaper, steel wool, etc
Note: The steps for making a threaded tip will require a die to make the threads. The thread for my screwy-style tip is metric 4mm-by-0.75, and this is the same thread as RadioShack(tm) part #64-2073
Regarding substitutions for materials or tools, if you want to use pliers instead of a vise, brass instead of copper, etc, that's cool ese, with the usual caveats about YMMV.
Step 3: Straighten the wire.
One important thing to keep in mind is the (very pure) copper used for electrical wire is somewhat soft, so if you try really hard you can crush it with the vise, and that would be undesirable. You want to hold the piece in place without marring or squashing it too much.
The simple act of closing the jaws will straighten the wire a little bit, but most of the fine adjustment is done by hand, bending the wire at the point where it enters-exits the side of the vise. The way I do this is by imagining a perfect straight line running right between and parallel to the jaws of the vise, and then bending the wire back towards this line if the wire veers away from it.
In the picture below I'm working on the wire where it touches the right side of the vice, just in that spot.
When that tiny segment looks straighter, I open up the vise and move the whole piece to the left a little bit, and clamp it down again. Then I straighten the next perceptible segment. As I do this, the wire to the left of where I'm working gets progressively straighter.
Then it's pretty much lather, rinse, repeat, until the wire looks like it's straight enough.
Step 4: Cut off a chunk.
Every good hacker should have a hack saw. It's a tool that comes in handy.
I think the length of this chunk was approximately 65 mm or 2+1/2 inches.
The size will depend on the depth of the hole in the soldering iron it is intended to fill.
Step 5: Load the chunk into the drill press.
It's hard to tell from these pictures, but in all except the first and last pictures below, the spindle is actually spinning while I grind at it with the file, sandpaper, steel wool, etc.
The camera does a good job of capturing an instant in time. While working the piece I don't see what the camera sees. I just see a blur because the spindle is moving so quickly.
Step 6: Slim down the tip diameter.
So I load it back into the drill press, and I grind it down just a little bit, uniformly reducing the diameter the same amount across the length of the cylinder. This of course involves stopping to flip it upside down, to grind the part I couldn't touch the first time because the jaws of the chuck were in the way.
In the last picture, I check the fit again, and the tip slides neatly inside the body of the soldering iron.
BTW, 6 AWG wire (six gauge wire) is almost not exactly 4mm in diameter. It is 4.115 mm in diameter.
Also the spec for the soldering iron might not be 4mm. It might be 5/32 inch, which is 3.969 mm
Step 7: Make it pointy.
Second picture shows the soldering iron and its new finished tip side by side.
Step 8: Steps for a threaded soldering iron tip
Make threads. (Step 10)
Make pointy end. (Step 11. Similar to step 7)
Step 9: A nice little cylinder
Step 10: Making threads
I'm not sure what the verb is for cutting threads on the outside of a rod. I think it's "thread". It's not "tap". That's for holes, and the tool that does it is called a "tap". In this case the tool is called a "die", but I'm certain the verb isn't also "die", as in, "Here, could you die this rod for me?"
"Gee, I dunno boss. Looks like it's already dead."
BTW, the size of this thread is M4-by-0.75. That's 4mm with a pitch of 0.75. At full res, you can just barely see the inscription on the die in the second picture.
Step 11: Make the end pointy - trickier this time
The thing that is different this time is that I want to tighten the chuck right on top of my pretty newly cut copper threads. I don't want these threads to be crushed by the jaws of the chuck, so I have come up with a little contrivance to protect them. It's a little rolled up piece of beer-can-aluminum that goes around the outside of the piece to protect it by evenly distributing the forces of the chuck jaws.
Step 12: Done
Step 13: Brass tips
The thermal conductivity of brass is only about 1/4 that of pure copper. See: