UnPossible

UnPossible

Well Known Member
Hey - I just finished up riveting my second roll bar for my RV-7A tip-up.
I wasn't happy with the first one, so I took what I learned and built a second.

Last night I reveted the whole thing together. The gap is now almost uniform, the height is pretty much spot on, but somehow in the process of reveting it together, the width has shrunk from 42 and 5/32 to 42 and 1/32..

If it was a bit wide, I'd just use a strong ratchet strap to bend it slightly into place. However, with it being a bit narrow, I'm not coming up with any great ideas as to how to spread it a bit..

Anyone else have this same issue, or have a suggestion as to how to spread the rollbar 1/8"?

Thanks,
Jason
 
Jason

You can easily pick up an eighth of an inch on your plexi canopy
install by either installing aluminum shims or sikaflex.
Regards
 
I built a jig as well, with stops both the height and width... for some dumb reason, I did not put a stop at the inside to prevent it from coming in when riveted.
 
1/8" means only 1/16" for each side. That little space may not matter as much as your canopy sides will fit in there when in closed position. You can put a shim in there as Lorne has suggested it.

Good luck
Mehrdad
P.S. Don't get frustrated on the roll bar, the canopy is next.
 
Hi Jason,

Have you tried a hydraulic bottle jack & a piece of 4x4, cut to length? Another possibility would be a 'pipe clamp' that's intended for gluing wide panels like tabletops. Some of them can be reversed to work as spreaders.

Either way, I'd be cautious about distorting the open ends of the assembly. Maybe you could carve hardwood plugs to fill the open ends.

Charlie
 
After some playing around and speaking to Gus at Vans, I think I have a solution. It doesn't take a ton of force to spread the rollbar the 1/16" of an inch I need. I used a 1/2" threaded rod to spread the roll bar. I should be able to drill and bolt the attachment agles to the fuselage and with the threaded rod inplace, slip the roll bar on to the angles and remove the rod....
Sounds good in therory, now I hope it will work in practice

Thanks,
Jasonn
 
Jason, I think I would try to expand the roll bar slightly over dimension and allow for spring-back. I don't think I would install it under tension. This is asking for long term trouble. With vibration, the roll bar will always be "trying" to return to it's natural state.
Just my $.02
 
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