vmsguy

Hello all,

I was at the airfield Saturday, my plane landed safely, and as it rolled out the nose gear broke.

The nose gear on my bird is your typical bent wire:

http://www3.towerhobbies.com/cgi-bin...?&I=LXD844&P=7

I cut the top to length, and put a 90 degree bend at the bottom where I wanted the wheel.

The break happened right at the bend. I suspected metal fatigue.

I stopped at the LHS yesterday and bought two more. (All they had on hand.) My idea was to re-cut/bend the new ones so I had a replacement and a spare.

On one of them, the wire broke right at the bend, as I was bending it. I know there are axles that slide on the length, and a screw hold them in place. But I always wonder if that type of axle will work it's way loose, and be more trouble than it's worth.

Again, I believe there's trick to bending this material correctly.

I want to apply heat, but I am afraid I'll ruin the metal's temper.

Thoughts?


TIA

Lyndon

MajorTomski

The bolt on axles work just fine if you file a flat for the set screw and use a little thread lock.

I suspect your wire broke because you might have been trying for too tight of a bend.

Heating it up till it bends easily then quick quenching in light oil or water will restore enough temper that you won't notice the diff for most landings.

HTH
T

Laird SS

I wouldn't be surprised if quenching heated music wire in water would make it extremely brittle. You would need to temper it after quenching to leave it hard, but not brittle. The bolt-on axles are the best bet. Much less trouble.

Flyboy Dave

My Feedback: (21)

....I heat the thick wires because they break sometimes, and even when they don't break
the bent area can crystalize and break later. I don't quench them, rather just let them cool.

FBD.

bassfisher

My Feedback: (21)

Forget the nose gear and convert the plane into a tail dragger.

Dr1Driver

Don't heat the wire. That will take the hardness out and make it weak. You're trying for too tight of a bend. I'd use a K&S Mighty Wire Bender and take it slow. Why not just buy pre-bent gear?

Dr.1

MajorTomski

And that's why it should be quenched after the heating to restore most of the hardness

http://www.dfoggknives.com/hardening.htm

Dr1Driver

And that's why it should be quenched after the heating to restore most of the hardness

And that's why it shouldn't be done to begin with. Proper heat treating and tempering is not a simple heat/quench shade-tree process. It requires the proper temperature for the proper time and the proper quenching time/medium. If it's done "by guess and by gosh" (as my Daddy would say) it won't be right and the part may fail, either in breakage or bending. It won't be good as new. Don't risk a nose strike (possibly damaging the airframe) with improperly hardened/tempered nose gear.

Dr.1

Flyboy Dave

My Feedback: (21)

...any length nose gear, and any thickness can be purchased easily and readily.
I wouldn't even try to bend the double circle that makes the spring action.

If you want to bend thick wire gear, bigger than 1/8" to make some replacement
or In my case, longer main gear....bent at 90 degrees you must heat it.
The wire I bent crystallized and broke when I bent it 90 degrees. You can hear
the sound of the crackling metal. Ferrous metals cannot be bent 90 degrees
without heating it....plain and simple.

Like I stated before....if you were to get it bent, it would be very, very weak.

The wire I used was purchased at the hobby store, its purpose was for landing gear
wire. It cannot be bent at sharp angles without heating it cherry red, like any other
ferrous metal that you would desire to bend. When it cools, it is quite strong. Try to
bend , by hand, the bend you just made after it cools....you can't.

FBD. (edit for spelling)

Ed Smith

That simply is not true. That statement is far to general. Take a look at any vehicle and all of the stamped and bent components. None of those were heated in the manufacturing process. In fact door skin edges are bent 180deg.

I have bent many music wire landing gears at 90deg without heating. So many too numerous to count. The max dia I have bent is 3/16" I have never had reason to go larger than that. The secret is to ensure a radius in the corner of the bend. In general terms the corner radius should equal the wire diameter. I have experienced different quality/temper? of wire from hobby stores resulting in the occasional breakage.

Ed S

Flyboy Dave

My Feedback: (21)

.....true ED, I should have stated "tempered ferrous metals". Certainly maleable, thin
ferrous metals....like sheet metal that are designed to be bent cold need not be
heated. Than you for the correction.

This statement is true, however....because I have done it....

FallDownGoBoom

My Feedback: (1)

Or, if you want to avoid the whole issue of heating, bending, quenching, and are willing to spend a little money...

What about using a Fults nose gear? Yes, it's $15-$20, and there are more screws to loctite down, but (1) the pivot post is thicker than normal wire gear, so it doesn't bend as much when subjected to "less than graceful" landings; the camlock mechanism seems to resist the nose wheel twisting out of alignment better than the usual 6/32 set screw; and you can easily adjust the attitude of the plane on the ground.

FrancisPerson

As stated before, buy a K&S wire bender. I have never had anything break.

Francis

Dr1Driver

If you want to bend thick wire gear, 1/8" and bigger to make some replacement
or In my case, longer main gear....bent at 90 degrees you must heat it.
The wire I bent crystallized and broke when I bent it 90 degrees. You can hear
the sound of the crackling metal. Ferrous metals cannot be bent 90 degrees
without heating it....plain and simple.

Plain and simple, that's wrong, Dave. If you need to heat your wire, you either have the wrong type of wire or you're doing the bend wrong. Using the K&S Mighty Wire Bender and a bench vise, I've bent 3/16" music wire from the LHS over 90 degrees without heating, crystalizing, or catastrophic failure. Bend it slowly and in stages to approxmately the correct angle, then let it relax a little before finalizing the bend.

Dr.1

Flyboy Dave

My Feedback: (21)

.....I believe you, Dr1.....you don't really need to make a Federal case out of it.

I'm sure that there can be a wide variance in the quality of wire available these days,
perhaps most or all of being imported. The wire I tried to bend could not be bent 90
degrees with out breaking it....I'm not making this up for the sake of conversation.

I would say that....if the wire you are bending lends itself to bending with out cracking
or breaking....fine, bend away. If the wire you are bending is fatigueing or breaking,
heat it up and bend it the same way you would heat and bent any other type of steel
wire....just that simple.

You didn't see me tell anyone they were just plain wrong, did you. Give it a break DR1.

Use the technique that works for you....heating steel to bend it is quite common. You act
like it is the most terrible thing you can do.

FBD.

Dr1Driver

You didn't see me tell anyone they were just plain wrong, did you. Give it a break DR1.

No, I didn't see you tell anyone they were wrong, but I did see you make a blanket statement what was incorrect. FYI, I'm not a heat-treating expert, but I've had college-level courses in metals and heat-treating during my Mechanical Engineering deucation.

bent at 90 degrees you must heat it.
Not correct.

Ferrous metals cannot be bent 90 degrees
Not correct.

Dr.1

ecmiller

Ferrous metals cannot be bent 90 degrees
without heating it....plain and simple.

As a former metallurgist and tool die maker, the above statement by Flyboy Dave is simply not true. Grain structure, type of alloys in the steel, percentage of carbon, heat treat temperature, time at temperature, quench medium, temperature of the quench medium, not to mention a few others, all have a play in the end quality of steel.

You simply have wire that is low quality, nothing more, nothing less.

Flyboy Dave

My Feedback: (21)

I must modify my statement that I already stated was incorrect, so we don't have too
many Members getting excited about finding an error in someones post.

Some ferrous metals cannot be bent 90 degrees without heating it.

The metal wire I purchased could not be bent sharply, at a 90 degree angle without
heating it....it snapped in half. I hope this simple fact doesn't cause much more alarm.

The fact is, just about any decent ferrous metal, with the exception of thin sheet metal, and thin
band iron has to be heated to bend it. Some need heating to psysically bent the metal (too thick)
and others need to be heated to prevent stress, and eventual failure...ask a Blacksmith.

FBD.

Charlie P.

Yep. Bailing wire is ferrous and, Lord knows, I bend that in loops, spirals and twists all the time. I'm holding a carb down on one of my favorite planes with it (the barrel bolt stripped and costs as much as a replacement engine to order).

Hardened wire may need heating, may nut. I've bent 1/8" K&B music wire full 360ΒΊ loops plus 90ΒΊ to make landing gear "mousetrap" springs with Higley wire benders and a large pin-punch as a mandrel. Just have to work slow and apply steady pressure . . . and hold your tongue just right.

scratchonly

I have ground a radius in a section of my vise jaws so I'm not bending over a sharp corner. I would guess about a7/16 radius; I hold tension on the wire and tap it with a hammer. Works for me.

Big Bopper

I tried bending that cheap hardware store wire without heat. No good. It broke.

Dr1Driver

I tried bending that cheap hardware store wire without heat. No good. It broke.

That's why I buy expensive LHS wire from K&S. Works every time.

Dr.1

Deadstik

My Feedback: (8)

Not wanting to step on anyone's toes here but whomever said it was a matter of the quality/type of wire is the real winner here. While I'm not a big fan of the K&S wire bender, (had a problem getting consistent bends..not sure why),I have been using Hobby Lobby's "best wire bender" for years to bend all the landing gears for my kits and that includes both nose gears with multiple coils and main gears plus different types of retract gears. As Ed said above, in sizes up to 3/8" with absolutely no problems and no complaints. I simple use the bender slowly, without any heat, and make each gear exactly the way I want it.....but... back to the main issue... I use ONLY K&S wire....and have never had a break or a failure.. and as long as my customers are happy, I'm happy...there are time when you can save money, and times it's best to pry open your wallet..

Dan
Carolina Custom Aircraft

Flyboy Dave

My Feedback: (21)

Lyndon....on that type of thick 5/32" metal you need to heat the wire, so what I described in
my first post won't keep happening. That metal doesn't have the high quality of some of the
other wires.

If you heat the wire red hot with a propane torch, or a regular welding torch, you will
get a perfect 90 degree bend....and it will not break later....honest.

FBD.