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A chinese's PA18 project----I need your sugestion.

As far as welding rod and technique, I'd use the same as you are comfortable with on the fuselage tubing. Unfortunately I cannot speak knowledgeably on the further welding specifics, sorry.
 
Use a heavy duty bender bench,I bend all my (heavy duty)bracket,why I say my bracket are heavy duty,because I can't find .1or.9inch thickness 4130N plate,so I use 3mm 4130 plate,about .118inch thick. IMG_3777(0).JPGIMG_3782.jpgIMG_3785.JPGIMG_3787.JPGIMG_3788.JPGIMG_3790.JPG
 

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Torque tube rear bearing use 1.6mm about .062inch 4130N steel plate,not all with .118inch thichness plate.
 
One thing I want tell all forks,I made those parts are very cheap,I am not sure why those parts made in USA are very expensive?Some of price are 10 times of my price.If somebody want those parts,I can made for you,just at price $5+shipment for one. :-x
 
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The earlier post concerning cost, remember it's relatively expensive to live in the U.S.A., Most of the parts come from FAA approved shops, I think even raw materials are more expensive here and don't forget our lawyers. Only the government section of the phone book has more entry's than the legal section so a lot of liability risk here. I'm sure the owners live a little better than the workers but unless the aircraft part is a side business I don't think we have to many really rich shops over here. Were lucky we have the decent businesses supporting aviation that we do. Very specialized and a lot of one off parts. All that said it's still expensive for the hobbyist. The aviation businesses here are of course low hanging fruit if China wanted to go after them but I can't see how it would be worthwhile except for maybe the amateur built market and we are pretty fickle.

Your parts look real good! I have made some of those from scratch and I know how hard they are to figure out. Are you still coming here eventually or do you think private flying will become more encouraged there? My sons girlfriend returns to Beijing on Saturday.
 
Both of these parts are not airworthy. They both have sharp corners and notches where the bend is made. This will start a crack over time and will fail. The first part holds the wing on the plane.

as I turn around and look at the Airframes fuselage, and it looks to be the same bend radiuses.... and those are each only HALF of a 2 piece welded item, the notches get disappeared in the edge welding process....
 
Both of these parts are not airworthy. They both have sharp corners and notches where the bend is made. This will start a crack over time and will fail. The first part holds the wing on the plane.

I saw that (the notches at the bends) but figured he had followed the original blueprints and somehow those were not finished yet. Sky can those be made airworthy by finish welding across those areas? I know that is a very basic question but I don't have a welding background and is one of the reasons I have to really follow the plans to the lletter as much as I can since I don't have good knowledge in that area. Good catch.
 
Looks like Mike answered my question as I was asking it. Maybe.? I guess the basic question: "Can't welding fix anything?" A good weld is assumed. My local mechanic took a look at one of my gas welds on an aileron hanger and said it was no good. I have a bunch of parts to build these but I'llprobablyhave someone else finish weld any welding I need. I would not attempt a fuselage like Sage is doing. Very impressive to me.
 
as I turn around and look at the Airframes fuselage, and it looks to be the same bend radiuses.... and those are each only HALF of a 2 piece welded item, the notches get disappeared in the edge welding process....

Mike , I'll agree on the lift strut fitting. I don't know what those other fittings are. Those cuts right at the reverse bends look bad. Are they welded? Depending on their use that could be a highly stressed area.
 
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The earlier post concerning cost, remember it's relatively expensive to live in the U.S.A., Most of the parts come from FAA approved shops, I think even raw materials are more expensive here and don't forget our lawyers. Only the government section of the phone book has more entry's than the legal section so a lot of liability risk here. I'm sure the owners live a little better than the workers but unless the aircraft part is a side business I don't think we have to many really rich shops over here. Were lucky we have the decent businesses supporting aviation that we do. Very specialized and a lot of one off parts. All that said it's still expensive for the hobbyist. The aviation businesses here are of course low hanging fruit if China wanted to go after them but I can't see how it would be worthwhile except for maybe the amateur built market and we are pretty fickle.

Your parts look real good! I have made some of those from scratch and I know how hard they are to figure out. Are you still coming here eventually or do you think private flying will become more encouraged there? My sons girlfriend returns to Beijing on Saturday.
Yes,I got a Interview Invitation Notice that form Canada at 29th this month,but I will go to Yakima frist,for my tailwheel endrosement.Congratulation to you will got a daughter-in-law,but be careful,chinese daughter even in law would empty your wallet.Lol,a joke.I have to Canada eventually.
 
Both of these parts are not airworthy. They both have sharp corners and notches where the bend is made. This will start a crack over time and will fail. The first part holds the wing on the plane.
Really?but I dont think so,they are made of .118inch(3mm) thick 4130N steel plate,thicker than normal PA18 buleprint shows,the notches came from my design for aim of bend easy and reduce stress,they will be weld togther when install.Pls visit www.super-12.com,the parts they make same with mine.
 
And I want to say all my parts will be heat treat after they are welding finish by myself,use a small heat treat stove,because the stove are very cheap here,the picure of stove only $150USD in China.heatreat stove.jpg
 

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Some of parts are track welded,I am waiting a ceritified welder came to my city for finish welding.And I have over 10years engineer background,I am sure the notches is no problem after welding and heat treated.
 
And I will use electric heat string heat treat all the tube join of my fuselage.And the string can work with 110V 60Hz,only $10USD per feet.heatreat string1.jpg
 

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The bridcage structure are composed of triangles,you said would loosing shape/bow?Could you explain to me?Thanks.
 
If you are using a mild steel filler rod when you weld, dont bother heat treating. Post-weld treatment is only necessary if you use 4130 as your filler material.
 
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Time is flying,half a year is past,this January,I visited Yakima of USA,have a tour to Cubcrafters and YakimaAeroSport company for learn fly and more details of how to fabricate a cub.I flyed a Cessna150 and a 180cub in Yakima airport.The cub is really a amazing plane for fun.Very smoth,like a moive that named Avatar.I believe I had a correct choice,thanks all suggest me.Because I am very busy in those days,my job,family,kids,so,the process of my cub project havn't more progress,but I learned a lot and have more knowledge about cub.
 
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My instructor lead me visited this cub in Yakima,I know that's maybe famous but I couldn't understand the narration absolutely for my limited Enlish.The question is :this cub have a electric driver three section flap(I dont know the English name of this kind flap).Could anybody tell me which size or type electric driver pusher I can install on my flap?
 
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Before I leave America,the hardwards and parts I ordered arrived hotel.
 
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IMG_4055.JPGAnother question,I bought this fuel cap but forgot the flange,I could not find a suitable size for this cap in China.Who can tell me where can I buy it?
 

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