Hello from Poland,

Has anyone made an Alu main leaf gear?
- which angle to press bend, to achieve desired angle?
- which type of Alu to use?
- bending cold or hot, annealing process?

Janusz

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Hi, Janusz;

Well, since no one has replied yet...    Not to dissuade you, but that's a pretty big job.  The main leaf landing gear is a relatively thick piece of metal; I don't have my plans with me, but on my Cruzer I'm guessing that it's a least 1/2" thick. You would have to have a VERY heavy-duty bending apparatus to bend it! But, you may have such access.

I would guess that NO ONE has fabricated a factory-dimensioned main landing gear just because they don't have a) access to a bar of suitable stock of the right alloy, b) a bending apparatus, c) lack of access to annealing equipment, and d) it's probably just cheaper to purchase one. 

I understand the shipping costs may be prohibitive, but you really don't want to mess up something that is going to take repeated landing punishment.

I am scratchbuilding and have been trying to make the same decision. If you search you can find examples where people have bent their own landing gear. However it does require time spent  fabricating a press. When I priced materials though, I would have two chances to get the landing gear right before my cost exceeds what I could get it from Zenith for.

It really depends on what you are up for in terms of time and money. Like any part of scratchbuilding, I would not recomment fabricating this part if your goal is just to save money. You do it because you want to. Even if it does cost more.

Thank you for the input. I have an access to professional toolshop with presses and annealing equipment. They never done a plane leaf spring though.

Several have made them but there is work involved. 6061 T6 is listed in my 701 plans. They are bent cold no heat treat or anneal. 3/4 inch thickness and edges have to be radiused before bending. Mine is radiused and polished but I won't bend it til the weather warms more so I can get back into my airplane factory. Bend angles are given in the plans. How much overbend to allow for springback is yet to be determined as I will bend and measure. Dan

Yes the grove gear is heat treated 7075 from what I understand. If an individual chooses to build there own from 6061 which is what Zenith calls for in the plans it is to be bent cold without heat and left in that condition. Yes the gear will bend under hard landings. Is a grove gear nice to have? Yes it is. Is a grove gear necessary? No it is not.

Mr. Grove himself once told me that Zenith did a much better job of designing the CH-750 gear than it did on the CH-701 gear, and that little weight would be saved by using his gear on a CH-750.

You might want to consider buying a Grove landing gear for your build. They use a different stronger alloy of aluminum so the gear can be considerably less metal to provide the same strength. Supposedly a Grove main gear leg set saves about half the weight of the stock legs, about 15 pounds or so. That is a huge weight savings! Also, Grove can drill the leg before they bend it and install AN fittings - you end up with the brake lines down to the brake units inside the gear leg with just a short section of flex line going from the AN fitting at the base of the gear leg over to the brake caliper. Tidy, attractive, elegant.

I intend to use the Grove main gear for my build.

The thickness of the gear on my 750 is 3/4” or .750 6061, we bend this at work cold with no annealing needed. Cut the shape, radius the edges, then pay a shop with the equipment to bend it. I’d say it’s not worth the time to make a press and jigs if you don’t already have one. The spring back of Aluminum is usually around 30% however at that thickness I’m not sure. Heat will most likely help in this case. There is quite a bit of information online with specific information about bending Aluminum too.  Have fun and post your results!

-Todd

It's been done many times, here is a pic of fellow builder Robert Haines on this website. 

http://www.zenith.aero/photo/bending-landing-gear-scratch

Though, as a plansbuilder, I bought my gear from Zenith to save the headache. But, I do admire the spirit of ppl that choose to do all of it themselves. 

The Grove spring as I understand it is tempered 7075 , it is sent to a foundry to remove the spring temper , returned to grove where it is shaped then returned to the foundry to retemper NOT something you would want to do , Buy the Grove spring and be done with it ..TOO many people have bent the cold bent springs , 6^ I know of here in ALASKA ...BOB

And if you do go for the Grove main gear legs be sure to check with the manufacturer before doing anything that involves heat (such as powder coating) since heat will alter the temper of the material. Heat found in normal operations is not a factor but heat from finishing or other work could be.

As Bob Jones points out, the Grove gear, in addition to my point about being half the weight, is also stronger. A strong gear is a good thing. As already mentioned I plan to use the Grove gear - lighter, stronger, drilled internal brake lines, what's not to like other than the expense?

I agree with Todd, I bought the aluminum then paid my local metal fab shop to bend the 6” radius bends. I believe it cost about $125 for the aluminum 6061 t6 and another $100 for the bends. It was worth the money to have the make the bends. My shop wanted a short 24” piece to do a setup bend first.

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