pipercub6

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Hi People,

Just a quick question about bending the heavier music wire. I already have a jig made up for the shape I need but my question is if I heat it some (with a torch) to be able to make it bend easier, (I tried one for practice and it was really difficult) will it lose the return due to the heating. It's rather large gear for a Despardo 3000 and the only other alternative is a bigger investment than I would like to go right now. Thank you in advance for any replies.

Regards, Pipercub6

fritzke

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see here:
http://www.vaillyaviation.com/images...re%20_web_.pdf
Dave
The Cliff Notes version:
Heat to cherry, air cool, now it's annealed
form it
Heat to cherry, quench (now it's very brittle)
heat to 750 degrees f. (medium blue) air cool, and
hopefully you are back to where you started w/ tempered music wire.

g-rock

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PiperCub
An alternate way is to purchase drill rod and I prefer the oil quench type. Just follow Fritzke's instructions ant the annealing step. Quench after the two last steps in oil if oil quench is chosen. McMaster Carr is just one of the many places where you can purchase drill rod.
Gene

Red B.

Proper music wire is ASTM A228 carbon steel. It is cold drawn and not heat treated. In my experience heat treating music wire according to Roy Waillancourt's instruction restores some of the "springiness" to the music wire, but I have had several cases were a heat treated bend failed due to fatigue cracks. I thought it was my inexperience, but after letting a local tool smith do the heat treating I still ended up with the same problem. I have obtained the best result when cold bending pianowire around an axle, bolt (or similar) with a diameter that is approximately twice the diameter of the pianowire. Piano wire bent in this fashion doesn't crack, fatigue or lose its springiness.

pipercub6

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Hey Everybody,

Thanks for the info! Am going to try it this weekend.

Regards, Cliff

da Rock

Any ideas of a good source of quality wire? I'm giving up on the K&S available nowadays in LHSs. It just won't stand up like it used to.

It's softer than the OEM stuff in ARFs. I ran out of the stuff I bought back in the 70s while making a set of longer struts for an ARF that needed more ground clearance. Bought a bunch of K&S. Didn't need it, but it pays to have some stock in the shop. Everything I've bent from the new stuff has bent in use. Matter of fact, the ARF that needed the ground clearance.... the new struts work, at least the old wire does. The strut bent out of the new stuff has to be rebent about every landing.

Would love to know a good supplier of quality stuff who sells in lots as small as a dozen pieces.

tia

BMatthews

You too eh? I noticed that something was amiss compared to the wire of my youth something like 15 years back. My solution is to just use wire that's 1/32 larger for whatever the application of the moment calls for.

Pipercub6. It really helps if you bend it around a piece of round bar that's about twice the diameter as the wire. So your 1/4 inch wire should bend around at least a 1/2 inch diameter bending pin. Otherwise you DO risk cracks. IN fact even 1/2 inch diameter may not be enough depending on the wire quality.

da Rock

Yeah, I do the same when it's possible. I'm replacing the struts that fit into retracts. The wire that came in the ARF didn't stand up, and my K&S wire based replacements were no better.

I have found an internet supplier, Small Parts, Inc., and have ordered some of their stock. It's advertised to be A228 carbon steel, and will at least give me a clue if the K&S is up to specs.

If this new wire is as malleable, my next step is to open up the fitting in the retract and use the next size larger wire.

hopkimf

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I just bent the Jim Pepino Waco 1/4 landing gear cold with K&S Bender. The first bender broke, but the second one didn't. I used a 4 foot pipe on the end and one foot on the workbench to keep it in place. That's after I tried it hot and failed trying to re-heat treat it. One came out brittle and broke. The other was soft.

da Rock

OK, I've gotten the new stuff, bent some new struts and tested them. The new stuff isn't any better.

I've got a line on a guy with a forge. It takes something better than a propane torch to heat threat a strut uniformly. I might or might not go that route. What I do plan to do right now is..................

I just ordered some Robart #650 struts.

BMatthews

It'll take a forge or furnance to heat treat a landing gear. THe issue being that you can't do it in parts. The whole wire shape needs to be brought up to the critical temperature at the same time, held there for a few moments and then the whole thing quenched into the brine, water or oil before it has a chance to cool below the critical temperature.

Once hardened to a glass like hardness with the quench you can actually temper it with a torch played over the length in parts but to do the initial hardening it's an all or nothing sort of deal.

da Rock

Yes...........

I've got a line on a guy with a forge. It takes something better than a propane torch to heat threat a strut uniformly.

da Rock

It is interesting that the music wire of today is much more malleable than it used to be. I have a number of pieces bought back in the 60s. After seeing that the most recently purchased A228 bent in use as easily as the K&S did, I dug into my old stockpile to see if any old stuff remained.

I rigged a simple test with a pull scale and found the A228 and K&S bent at about the same torque. I pulled that with the old stuff and it deflected less and didn't take a set. I pulled about 15% more and still no set. Decided that was good enough for me because I really did not wish to destroy the future use of that good old stuff.

I wonder if cryo treatment would do anything? It's easier to arrange.

BMatthews

I found the same thing. The stuff we used to use back in the 60's and through most of the 70's was able to bend further without taking a set. And it seemed to be harder to bend as well. Today's wire reaches the plastic stage at lower angles and just generally isn't as good.