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Justin Hodges (280ZForce) LCA's


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That's what it looks like to me. Cary obviously disagrees, but that's what it looks like to my eye.

 

EDIT--Otherwise why are those hairs coming THROUGH the welded area? Might happen if you had the welder cranked up to 11 on wirespeed and the material was really thin, but the other welds don't look like that was the case and the matierial isn't thin. If there was a gap there, the wire can go right through and then hits, and then you'd be left with the hairs inside the clevis area. Speaking as a novice welder who has seen my share of crap like that when welding rusty Datsun bodywork, that's what it looks like to me.

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Is it possible as the first tab being welded on, it was welded also on the inside, thus hairs accruing, then the other tab welded on making it appear as you suggest?

 

BTW, are hairs left over wire?

Yes, those pieces of wire in between the clevis are the "hairs" I'm referring to. Not sure where I got that term from, but I believe it is the correct term. When you mig weld the wire comes out of the welder gun. If for example you miss the piece entirely and hold the trigger down, the wire just keeps coming out. So if you have an inch of wire hanging out of the gun and then you touch it to something close to the gun it welds at the base and you have an inch long "hair" hanging off of your piece. Usually they aren't really all that stuck on and you can just brush them off.

 

You normally don't get hairs if the wire hits the tip on the part you're welding to. That's how mig welding is supposed to work, so usually the wire just melts and becomes part of your weld. You can get hairs that way, but the WHOLE hair gets red hot and ends up bending. To me the hairs on your part look like the wire came from the outside of the clevis through a gap and were left there after the weld was done, which I interpret as a sign that 1. there was a gap there, and 2. this is crappy welding. I'm not an expert on welding.

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That's what it looks like to me. Cary obviously disagrees, but that's what it looks like to my eye.

 

I think you're right after looking at the larger pics. I just have no idea why someone wouldn't have put the plates next to the tubes.

 

Cary

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I think you're right after looking at the larger pics. I just have no idea why someone wouldn't have put the plates next to the tubes.

My guess is they cut the clevis pieces too short and it didn't fit the jig. Rather than fix the jig or the clevis plates, they made up for it in the weld.

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BTW... clevis plates and gussets should be welded on one side of the joint only. This is per FAA spec for CroMo welding and the book "Construction of Tubuklar Steel Fuselages."

 

I was wondering when someone was going to mention that.

 

Some of the welding was obviously tig and the rest mig. None of those welds would likely pass inspection or testing for various reasons. If your serious about running those without worry then I'd have them sent to a lab for non-destructive testing. Weld defects that I can visibly see in the pictures effect the quality and hardness of the metal. There is lack of root fusion, lots of weld splatter and the welds are very undimensional throughout, meaning not the same width along the weld. Overall they are extremely poor welds IMO and look to be the work of a novice at best.

 

Paint covers alot of defects, I call it a DuPont overhaul myself. If you remove the paint with some paint remover and use dye, you can detect porosity yourself. You can also magnaflux it cheaply at a auto machine shop and maybe see some signs of lack of root fusion since the weld never melted with the base metal. Ultrasonic testing would be a good idea also. x ray is kind of expensive.

 

And yes, they may work, but if they fail while driving the results could be a disaster. I would think it would be prudent to at least inquire about getting a quote for some testing by a qualified lab before you run those. Obviously the decision lies with the owner of the pieces and this is just my observations from the pictures provided and nothing more.

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I have no knowledge about the subject, but from reading I feel this thread has some good technical info that might help someone in the future... maybe someone making their own LCAs. Might be a good idea to move it to the suspension section?

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I have no knowledge about the subject, but from reading I feel this thread has some good technical info that might help someone in the future... maybe someone making their own LCAs. Might be a good idea to move it to the suspension section?

 

 

I agree, but its up to the red letter guy's... :)

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Just FYI, all arms made from this point on are going to be constructed with everything in this thread taken to mind and applied. Thanks to everyone for helping improve on the design by discussing the arms.

 

The old shop has been fired and a new shop will be used.

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