ArVeeNiner

ArVeeNiner

Well Known Member
Well, I JUST started to tweak my frame tonight. I read and read and read some more but I still managed to do some major damage to my canopy frame.

Everything on it actually seemed pretty close except that the center top rail that the latch attaches to was misaligned with the center of the roll bar brace. I was slowly bending in one side of the forward bow while bending out the other side when the kink happened.

I'm hearing that a new frame is like $500 shipped. There is a pretty good weld shop near work. Do you think that it would be worth having them give it a shot or just punt and call Van's with a credit card?

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I guess it's time to hang the engine!
 
I also tweaked my frame while building. I called Van's they said no prob and sent me a replacement for just that portion of the hoop (didn't even charge shipping). I took it to a local welder and $20 later (plus promise of a ride, since repaid) it was as good as new.

In fact, since I had horked that section anyway, I cut it which then made everything else easy to shift into alignment. Welder then just put the new hoop section in.
 
I did something similar on my 6 canopy. I tried to tweak it "just a little bit more" and it broke the forward bow up near the top through a hole I had already drilled. I got a piece of chrome molly tubing that would slip inside the bow and welded it back together. I used a little touch up paint and now the repair is invisible. One side benefit, the finished frame fits very well and will slide open with very little effort.
 
Wow, what a relief!

So, I'm not the ONLY one to have done this? That makes me feel much better and it sounds like there is a way to make it good without buying a new frame.

Kevin, what weld shop did you go to? I see you're in San Mateo. I work in Palo Alto and it would be good to go to a guy that has done it before. I have the frame in my truck right now and at lunch I'm going to take it over to Advanced Welding in Mountain View. They do a lot of work for the place I work at and a few years ago I had them weld the fittings on my aileron tubes.

So, you're saying that you bought only the portion of the bow that was bent right? So, we're just talking about half of the front bow right? Was it just spliced in leaving the existing welds at the top and bottom intact?

What did you do about paint. Rod, did you just use some off the shelf rattle can paint? No need to powder coat?

I'll call Van's to see how much the forward bow would be.

This is an amazing list. Thanks again!!!
 
Repair it

Kelly

Save the money and get it welded. I'll bet no-one will ever notice once it's painted.

Peter
 
easy fix

First straighten it out a little so the the canopy fits fine, then just squeeze it in a vise a little on the sides. While its in the vise drill a hole in the bend, and use a dent puller to pull it out. After that grind it down a touch, have the hole filled by welding, then bondo over it. You'll never notice it afterwards. You will have to be careful fitting it going forward though because its going to want to bend there if you need to make more bends
 
ArVeeNiner said:
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What did you do about paint. Rod, did you just use some off the shelf rattle can paint? No need to powder coat?

I'll call Van's to see how much the forward bow would be.

This is an amazing list. Thanks again!!!
Click to expand...

Van's sells a touch up paint that matches the powdercoat. It comes in a small bottle with a brush built in to the cap and matches perfectly.
 
I also put a little kink in mine (forward bow of slider frame). Asked "The Man" (Van) at Sun 'n Fun and he said what RocketBob did. Fix it best you can, bondo, paint, and move on. (I did not pull it out or drill, just sqeezed a bit and tweaked) Verify with the factory though. Note: mine was not cracked.

It was a sickening feeling when it happened. That I can relate to.
 
Mine isn't cracked, just kinked.

That sure would be easy. In fact, if I drilled a hole and pulled it out like Rocket Bob said I wonder if I could have the hole welded shut and ground down. Hmmmm.

UPDATE: The weld shop thought that 4130 would be very difficult to pull out. I also asked if a blob of weld would do the trick instead of pulling it out. He said that the wall thickness would make that difficult. It would remain a weak point.

I'm still weighing my options. Ken at Van's says that have some scraps that I could get. If I get a scrap of close to the correct radius I could have the weld shop put in.

A new frame is $320 + shipping. Ouch.

Then there is always Bondo without drilling a hole. I suppose it wouldn't hurt to bend things back in place and get it all adjusted, then do the Bondo trick. In the meantime I can buy a piece of scrap from Van's to have it ready for plan B which would be to splice a piece in. If all else fails there is always the new frame route.

Be gentle with your frames out there!
 
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Fix it - You'll have more $$ later on.

How strong does it need to be? The real stength at that position comes from the big roll bar.

What about cutting it, slip a smaller tube inside and leave a small gap. If you can't get a smaller tube, take a piece of sheet and roll your own. Put a welded seam around it and then grind down until smooth. It would be exceptionally strong and the seam would disappear after painting.

Also gives you a good reason to paint it to match the interior.
 
Bite the bullet

Personally I'd buy a new frame from Uncle Richard. Any licenced aviation welder will tell you that it will be problematic trying to fix that damaged frame without a kink and while maintaining frame symmetry. You may spend a lot of time and money having it TIG welded and still end up with a kinked or assymetric frame, mismatched paint, and inadequate corrosion protection.

I'm not saying it CAN'T be repaired. I'm just saying you'll need some luck and in the end you might end up just throwing good money after bad. And you'll certainly need a very experienced TIG welder who is used to working with very thin wall 4130 chrome moly.

Don't bother with the "Bondo" approach. If you "Bondo" the frame and then have further problems with it after the perspex canopy is fitted you will REALLY have a nightmare on your hands.

I'd put it all down to experience and look upon it as fees to join the club.

When you damage a part and ask for an opinion on the internet (regardless of how bad the damage is) there will always be people who will tell you to "bog it up with Bondo and move on". Unfortunately you will rarely be in a position to inspect the projects being built by those same people to get a real indication of where that philosphy leads to in terms of build quality.
 
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Cut and weld

I have heard from a couple of guys that ended up intentionally cutting and welding the tubing to achieve the best fit.

Take advantage of the situation and re-engineer/weld it to fit perfect. If you buy a new one, it's back to the drawing board re-shaping!

ff
 
No big deal

As one who has intentionally cut and welded something like three slider frames, I will give my thoughts.

Welding 4130 steel tubing with an oxy-acetylene torch is simply not a big deal. It is not difficult for someone who knows basically how to weld and operate an oxy-acetylene torch. This is how thousands of fuselages have been produced.

Slider canopy frames are notoriously unmatchable to the fuselage. Just look around the next large RV gathering for evidence. In three out of three frames that I got involved in, the solution was to shorten one or both of the rear bows. This was done by cutting out an appropriate length of tubing, and sliding some tube or rod into the two ends, and welding back up.

Of all the parts on the entire plane, the steel slider canopy frame is probably the least stressed part.

Kelly, I believe if you can find someone who has a torch, and who is a reasonably proficient welder, it could be straightened out with minimal trouble. Heat the problem area, have someone apply straightening force while you tap the buckled area with a hammer. If that doesn't work, cut out the offending piece and weld in a new one. Slide another short section of tubing inside, which helps with welding and alignment.

I know if I built another one, I'd get the canopy frame uncoated, just so that it can be "red wrenched" into submission.

Good luck!
 
ArVeeNiner said:
Mine isn't cracked, just kinked.

UPDATE: The weld shop thought that 4130 would be very difficult to pull out. I also asked if a blob of weld would do the trick instead of pulling it out. He said that the wall thickness would make that difficult. It would remain a weak point.

Then there is always Bondo without drilling a hole. I suppose it wouldn't hurt to bend things back in place and get it all adjusted, then do the Bondo trick. In the meantime I can buy a piece of scrap from Van's to have it ready for plan B which would be to splice a piece in. If all else fails there is always the new frame route.

Be gentle with your frames out there!
Click to expand...

If you were closer to me, I'd have you bring it over to my hangar and I'd have it fixed in 30 minutes. I TIG weld 4130 frequently, and its easy material to weld. Welding a blob onto it would work, in fact that would be a five minute thing to do. It would take longer to grind down though. I would consider straightening it out the best you can and use braze filler, that way its not as hard as steel and easier to grind, if you went that route. There's also an FAA approved repair to steel tubing you can consider, and its worth a try, and its the technique of drawing a steel ball thru the tube. If you can find a ball bearing that would fit the ID of the tube, you could drill a hole in it and rig up a steel cable to pull it thru. This might sound crazy but I'll bet it works. Drill a hole for the cable to pass thru on your workbench. Put the cable in with the ball attached thru the hoop, and out the other end then run that thru the hole in your workbench. Then rig up a lever underneath the workbench to the steel cable (2x4 or whatever) and pull the ball thru.

I kinked my frame in the -6 10 years ago, straightened it out a bit and bondo'ed it. After over eight years of flying, over 1000 hours, I still cannot tell where I kinked it.

Fix it and move on! :)
 
Prevention

I think that one way to prevent the "kink" is to fill the tubing with wet sand prior to bending it.
 
Update: I had the frame welded

I ordered a complete front bow from Van's for $25. My thought was to remove the entire front bow and weld the new one on. The welder thought that it would be cheaper and just as good to replace only the kinked portion. So, that's what I did. The weld job cost me $75. I got a rattle can of paint from Bryan Wood (flying the flag) that will match the powder coat.

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I have yet to continue fitting the frame at this point so I don't know yet if I'll get it close enough to work. So far, it is looking promising.

Thanks for all the support!!
 
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