Stick Jammer

Here's an interesting article that supports cold bending of music wire. According to the documentation enclosed, music wire is not heat treated to begin with.

http://www.djaerotech.com/dj_askjd/d...musicwire.html

Stickbuilder

I have been following the thread for the entire time. I have one question (anyone who wished to respond will do just fine) Is it possible to stress the gear to the point of fracture by having a hard landing? It seem to me that the stress required to bend 3/16" or larger wire would far exceed the highest possible stress that landing a model airplane of the weight that would allow the use of 3/16 music wire gear. In other words, if it takes that much energy to originally bend the wire, would it not follow that to deform or fracture the wire on landing, the landing would have been done with sufficient force to destroy the airframe? I have seen landing gear deformed, but it was not made from anything close to the kind of wire that K&S sells, but was normally wire that is often soft enough to bend using your hands, or at most a pair of pliers. I may be completely wrong here, but I have bent K&S wire both hot and cold, and I have seen the wire fracture when bent cold (normally smaller wire such as what I use in the Cabane struts) and I have hot bent wire as well, with better results for my applications. I don't claim to be a metalurgist, nor do I have the facilities available to me to restore the rockwell number to the wire that I use. I sure don't know the right answer here, but I do know how to make what I need and what works for me. Good luck guys.

Bill, AMA 4720
WACO Brotherhood #1

AA5BY

Good thread.. I've enjoyed it. I've been a modeler since '73 and have scratch built a good many models and always cold bent the gear... but admittedly all of it was 5/32 or less. I was also a metals major and have a couple of additional comments to the thread. Forgive me if I somehow missed someone making these points.

As someone pointed out, music wire is a cold rolled product compared to the much cheaper method of hot rolling. Cold rolling is easy to distinguish from hot rolling because hot rolling will have an oxidized flash covering. Cold rolling produces a much more uniform hardness and is used for higher carbon steel such as music wire and many hardnesses below it.

As has been stated, high carbon steels to be machined, are done in an annealed state. Annealing (softening) and heat treating (hardening) high carbon steel as stated by some is a fairly precise science though some good results can be had by amateurs with little equipment.

Heating music wire to bend it will anneal it if it is allowed to cool at ambient temperature. It does need an immersion to heat treat it, again please forgive me for repeating what has been said. My point and opinion is that heat treating a section of the wire is problematic in that the proper temperatures will not be uniform along the wire. Also, I don't recall any one commenting that the quenching process requires a quick figure eight movement. That movement is necessary to cool the item as quickly as possible...simple immersion will super heat the water next to the piece and it will cool too slowly. The comment about brine rather than plain water is correct and also the comment about oil, some process require oil.

Case hardening has been mentioned and doesn't really apply to our music wire but I'll make one simple comment.... it is the process of packing carbon on the exterior surface to harden the shell. It is done by packing carbon around an item and heating the whole in a furnace.

Basically, I'm in the camp that hot bending is too problematic for modelers needs unless some specific reason exist to do so. I've recently had more breaks in Z-bends when bending them and attribute those to variances in music wire quality and hardness. Maybe landing gear size wire is suffering some quality issues too... I've not bent a set of gear for a few years.

da Rock

I've bent a number of piano wire gears in the last couple of weeks. I guess I've gone through 6 or 8 piano wire rods. All were from 5/32" wire. I've got to second the idea that , . A couple of pieces of wire handled great. One was like glass. OK, maybe not that bad.

A couple of nights ago, I'd have typed this in ALL CAPS. I was bending some replacement struts for a buddy who's retracts came with "couldn't be steel, gotta be iron" wire struts. His daughter could bend them things. So I was whipping out some "quality" replacements. With my setup, I have to bend the coils before bending the right angles on the ends. Both ends had right angles. Darned if about 3 or 4 (I lost count) of them snapped at those right angles. One thing you need to do when trying for right angles is to insure that your vice has radiused jaws at the top where the 90degree is forming. If there is a corner there, it'll create a stress point after the wire has gone about 70-80 degrees and SNAP. And my vice has chamfer where it needs it. But some of the wire was crap. And after snapping the crap stuff, I lucked into a couple of pieces that worked like I expected it all to work.

MinnFlyer

My Feedback: (4)

My vise doesn't have a radius on the jaw, so what I do is: I bend the wire to a little past 45ΒΊ, then I raise it out of the vise by about 3/32 - 1/8" (about half the diameter of the wire) and continue to bend.