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  #1  
Old 03-10-2018, 07:07 AM
scottmillhouse's Avatar
scottmillhouse scottmillhouse is offline
 
Join Date: Apr 2007
Location: Madison, AL
Posts: 231
Default RV canopy frame bending

Has anyone come up with a safe way to bend the front hoop in tighter for a slider frame after being drilled for the canopy on a RV-7. I have built two sliders before and done it by sheer force but always before being drilled. Searches seem to show that if drilled they all break. Pulled in about 5” by ratchet and it just springs back. Of course it is fully disassembled off the plane.

Original builder obviously did not allow for any spreading effect of the canopy or matching the frame rails. The frame needs pulled in about a full 1” to allow for the 1/2" growth by the canopy installation.
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Last edited by scottmillhouse : 03-10-2018 at 12:14 PM. Reason: edit for completeness
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  #2  
Old 03-11-2018, 01:10 PM
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scottmillhouse scottmillhouse is offline
 
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Looks like no ideas so I'll plan to cut tubes to shorten and reweld rather then risk breaking it at a drilled hole.
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Scott- 2018 dues paid
Got medical back, now building a 7A; N579RV reserved, new engine installed, doing FWF, instruments & finish painting.
RV-12 #120515, N319RV 1st flight 12/2015 now over 270 hours.
RV-9A, 536 hours sold, RV-7 sold, Kitfox sold
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  #3  
Old 03-11-2018, 04:33 PM
rv7charlie rv7charlie is offline
 
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Location: Pocahontas MS
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If you're just looking for spit balled ideas, I'd consider trying a hydraulic tubing bender. Something like:
https://www.harborfreight.com/catalogsearch/result/index/?dir=asc&order=EAScore%2Cf%2CEAFeatured+Weight%2Cf %2CSale+Rank%2Cf&q=tubing+bender

These allow concentrating the force where you need it.

If you can find a mandrel to go in the bender that fits the tubing, it will minimize the risk of cracking the tube.

If you're willing to sacrifice the powder coat, a simple propane torch can supply enough heat to make bending manually (for a minor tweak) a lot easier.

Even an electrician's 'hickey' conduit bender and/or EMT bender *might* be able to do the job, if you can find a size close to your tubing size.

Disclaimer: I don't have a slider canopy. I have, however, used a HF bender, an electrician's 'hickey', EMT bender, and propane on other stuff. I know propane will work on 4130 tubing. The benders will depend on how much you need to move it, and how close the mandrels come to fitting the tube you're trying to bend.

Charlie

Last edited by rv7charlie : 03-11-2018 at 04:36 PM.
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  #4  
Old 03-11-2018, 06:47 PM
terrye terrye is offline
 
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Location: Vancouver, BC, Canada
Posts: 706
Default RV canopy frame bending

The hydraulic pipe benders (note these are sized for pipe, not tubing) will only work on "free span" portions of the front/rear hoops, not close to the round top tube or the square side tubes.

I ended up making an open side bender using a "T" shaped frame made from 3" x 1-1/2" x 1/4" channel, a "porta power" hydraulic pump and ram and some bending shoes made from hardwood. The "T" was bolted together web to web, and a bracket was made with gussets to accept the ram at the other end. Wish I'd made this first.
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  #5  
Old 03-11-2018, 08:00 PM
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scottmillhouse scottmillhouse is offline
 
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I'd try all ideas again if it did not have holes already drilled every 2" on the hoop. Vans and everyone else says it will break at the weakened location with a hole. Thinking so far the only safe way is to cut and reweld.
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Scott- 2018 dues paid
Got medical back, now building a 7A; N579RV reserved, new engine installed, doing FWF, instruments & finish painting.
RV-12 #120515, N319RV 1st flight 12/2015 now over 270 hours.
RV-9A, 536 hours sold, RV-7 sold, Kitfox sold
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  #6  
Old 03-11-2018, 08:49 PM
E. D. Eliot E. D. Eliot is offline
 
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Location: San Pedro
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Default Bending

Think that I'd cut it off, get a new piece or two of the same number aluminum tubing (in my case, it might take two in order to get it right), bend it on a wooden frame with the desired radius, and have it welded back on. Some welders can do absolutely beautiful work with aluminum tubing. That way, you will never have any doubts or concerns that it was done right. Best to you
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  #7  
Old 03-11-2018, 10:33 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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I have adjusted steel canopy frames by small amounts after the canopy was drilled.
In once instance I did it even after the canopy was riveted to the frame. Risky, but it only needed a little but of change to the width.
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  #8  
Old 03-12-2018, 12:09 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by scottmillhouse View Post
I'd try all ideas again if it did not have holes already drilled every 2" on the hoop. Vans and everyone else says it will break at the weakened location with a hole. Thinking so far the only safe way is to cut and reweld.
You can notch the tube (think of felling a tree) where you want the extra bend and re-weld. That would be a lot easier than fully cutting the tube and re-welding. I can't imagine your going to get the holes in the plexi to line up though. You could explore the possibility of moving the plexi back about 1/2" and redrilling the plexi (should be able to match the hole visually). Making the front f/g fairing a bit bigger should cover it up. You can also consider an adhesive instead of rivits to save the canopy. You can fill each hole with epoxy before gluing. I can't imagine that there is a structural need for the canopy to be attached to the hoops, as long as you provide a buffer to eliminate vibration and movement between the tube and plexi. The tippers don't have that support.

Larry
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Last edited by lr172 : 03-12-2018 at 12:12 PM.
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