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#1 shootnstarz Sep 29, 2011 08:20 AM

Straightening Aluminum LG
 
I am doing a repair job on a 35% Edge and the aluminum landing gear is bent. Someone told me to heat it up to straighten it. I know the old fashion vice and hardwood blocks won't work on a gear this thick.

What's the best way to straighten out these large landing gears?

Rick

#2 DT56 Sep 29, 2011 09:05 AM

Quote:

Originally Posted by shootnstarz (Post 19453944)
I am doing a repair job on a 35% Edge and the aluminum landing gear is bent. Someone told me to heat it up to straighten it. I know the old fashion vice and hardwood blocks won't work on a gear this thick.

What's the best way to straighten out these large landing gears?

Rick

Depending on the alloy, heating can anneal the aluminum, changing the temper. That might take the spring out of the gear, so I'd just bend the gear back into shape. A pipe wrench with wood jaw pads can add the leverage required to bend heavy duty gear, especially if a pipe extension is added. Aluminum is notch sensitive (prone to tearing), so if the edges of the gear are sharp or have nicks, you might consider filing a slight radius to the edge prior to bending. Soft jaw pads for any clamps that might be required will reduce the risk of further damage to the surface of the gear.

#3 sscherin Sep 29, 2011 11:16 AM

Follow Campy's advice in this thread..

http://www.rcuniverse.com/forum/m_97...tm.htm#9707507

#4 BMatthews Sep 29, 2011 06:12 PM

A buddy that works on airframes for a local aircraft company told me about a trick that is similar to Campy's felt pen indicator. The trick is to soot up the areas to be straightended with a candle or butane lighter. Get the areas good and sooty. Then using a propane torche fan over the area and heat it until the black all goes away. At that point you have an hour or two to straighten the piece. If it needs a LOT of bending repeat the sooting up and propane torch annealing mid way.

This annealing with either felt pen or soot is temporary. The original heat treatment conditions will restore itself within a day or two whether you bend the metal or not.

Yes this is highly odd sounding compared to how carbon steel items are treated. But the alloys of aluminium are not steel. They respond very differently.

#5 leaktech Sep 30, 2011 01:25 AM

Big Jorgensen clamps are usefull in this task.

#6 DGrant Sep 30, 2011 02:21 AM

Quote:

Originally Posted by shootnstarz (Post 19453944)
I am doing a repair job on a 35% Edge and the aluminum landing gear is bent. Someone told me to heat it up to straighten it. I know the old fashion vice and hardwood blocks won't work on a gear this thick.

What's the best way to straighten out these large landing gears?

Rick

I've found an old picnic bench thats very sturdy and secure serves as a nice leverage point. The bench has to extremely strong, like you'd find in a state-park, or maybe even your flying field.. thats where mine are.. Stick it between the slats strategically and bend away. Its not that hard to bend these types of gear. If it bent out of shape, it will bend into shape..guarentee it. I'm about 280lbs.. I have no problem bending it any way I like.. given the correct leverage. You don't need heat.. I'm sure there was no heat when it bent out of shape.. and if you're not 280lbs there's always a way to use "cheater" bars. You probably don't even need a vice if you can find the type of table I'm talking about.. and vises just leave ugly grip marks.. haha...Id rather have bent gear then something with teeth marks. :)

#7 shootnstarz Sep 30, 2011 07:25 AM

Thanks for all the info guys, and the lessons in metalurgy. I have the bent pieces straight in clamps with oak blocks and they've been sitting for 2 days. I'm sure this will take a lot of the bend out. Fortunately it's not bent at the original forming bends but futher down the leg. I believe I can take the rest out by hand. There are no creases in the bend but just a gentle curve.

I will straighten it out as best I can with the oak and clamps, the owner complains the gear is not heavy enough for the plane so I'll give him the option of replacing it before I re-install the old one.

I am truely unimpressed with how the LG was mounted in this plane anyway. 3/16 lite ply is not my idea of a strong LG mount. I have now replaced it with 3/8 Finland birch and several reinforcing pieces.

Rick

#8 LesUyeda Sep 30, 2011 09:31 AM

"I will straighten it out as best I can with the oak and clamps, the owner complains the gear is not heavy enough for the plane so I'll give him the option of replacing it before I re-install the old one."

I have been known to take bicycle spokes, and run diagonal bracing from the fuselage to just above the opposite wheel. Worked just fine on soft gear.

Les


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