RODCHUCK

Tip #1 - Threading Music Wire.

We are often asked can you thread music wire. The simple answer is NO. We tell folks if you can file it, you can thread it. The hard music wire will quickly dull a set of dies.

The exception is if the end of the wire is "annealed". The annealing requires that the wire be heated to a cherry red and then allowed to air cool. In doing this the temper or hardnes is removed from the spring music wire. A normal Benzine torch is adequate to heat the wire of either 1/8" or 3/32" size.

In most cases you will want to control how far up the wire the annealing will travel. After all for some reason we want the spring properties of the wire to remain. To accomplish this a "heat sink" is needed to isolate the annealing heat to the area of interest. The heat sink can take any form but it must be heat conductive, fairly large in mass, and be in tight contact with the wire. A large bench vise works well. I have used a coffee can full of wet sand. In some cases a large pair of vice grips will work.

No matter which sink is used, place the wire so that just the end to be annealed is sticking out of the heat sink. Apply the torch until the area is glowing red hot. Then remove the heat and allow the wire to cool completely. At this point the area that was heated should now be soft enough to thread, but the wire in and beyond the heat sink will still retain the original spring properties.

I hope this helps.

Tip #2 - Differential Screws

Here is a technique you might want to try.

In the June 1998 issue of Model Airplane News there was an article "How to Mount Wings Using Differential Screws" by Al Ehrenfels. The basic principle is that if you put two different thread pitches on the end of a rod you can create a "turnbuckle" effect even though both threads are right handed. I would encourage you to read this article.

Here is how RODCHUCK can be used. Since a commercial 4-40 rod is a "rolled thread" the actual rod is 3/32" in diameter. This means that an end of the rod without threads can be threaded with our 2-56 die set. If you do this then you will have a 4-40 thread on one end and a 2-56 thread on the other. Standard screw on clevises can be used to terminate the rod ends.

To use the rod, first screw the 2-56 clevis in as far as practical. Then just start the 4-40 clevis on the rod.

Anchor the 2-56 and 4-40 clevises to their attachment points. Then as you screw the rod "into" the 4-40 clevis it will "unscrew" from the 2-56 end. However since the pitch is different (56 threads per inch Vs 40) the rod will unscrew 1/56inch per turn and screw in 1/40th inch per turn. The distance will become shorter between the two clevises by 0.007" per turn. With commercial rods I found that approximately an 1/8 inch of adjustment can be achieved (18 turns). I plan to use this technique on my next giant scale that needs tail brace wires. But I am sure there are other applications for the technique.

By the way don't forget a "jam nut" on one end to keep the rod from backing out and loosening once the vibration starts.

If you have any tips on how to use the RODCHUCK you would like to pass along please drop them to us by email and we will post them.