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RV8R999

Well Known Member
I used SIKA to install my windscreen, canopy and skirts. I like the way it came out and after testing several pieces am convinced of the structural integrity, as has been discussed many times.

I used my extra SIKA to form nice fillets along the rollbar and canopy bow structures but I don't like the look of the joint from the inside when the canopy is closed. Basically I don't like the wedge shape, it looks unrefined and sloppy to me.

my canopy and windscreen mate up with only about 1/16" gap all around but since I made the "big Cut" along a projected vertical line tangent to the aft face side of the roll bar the canopy extends over the canopy bow about 1/2" thereby creating an odd looking joint.

I was thinking I could mix up a thick epoxy (quick setting) and micro solution and pack it into the joint from the inside (taping, waxing, and mold releasing the forward part) forming a perfectly mated joint between the two halves. I'd put a spacer in to accommodate some type of weather strip as well. I'd take a short nap while it sets and then sand an finish or maybe even add 1 layer of glass for structure.

Any thoughts?

Has anyone painted over SIKA? I tried a test sample and the paint is still sticky after two days....Hmmm???

Ken
 
Attached is a pic of the rollbar joint after I painted it today -
2n6ugef.jpg
 
Refining the Joint between Canopy & Windscreen

Ken

I did my windscreen, canopy & skirts with Sika just like you - perhaps with a smaller overlap. You have done a very neat job of finishing & painting the exposed Sika & I would suggest leaving well-enough alone, bearing in mind that the canopy is closed most of the time & the joint will largely be concealed by the fibreglass strip over the bow.

I spent more time getting the outside right - it is much more visible & hard to conceal defects with the thin fibreglass strip over the bow.

I first used an epoxy flox mixture on the windscreen edge to perfectly match the windscreen & canopy (my canopy moved a touch while being bonded)

I also chose to have the canopy skirt slide under the windscreen. To accommodate the thicker Sika joint on the skirt I built up about the bottom 6 in above the skirt on each side to create a smooth transition for the windscreen bow fibreglass - worked out very well.

2 years later I still notice the minor defects on the external fibreglass, I don't
notice the inside details at all.

I used an epoxy primer & polyurethane topcoat - no problems other than a couple of very fine cracks due to slight shrinkage of the Sika (I think)
I recall that use of solvent based paints is not recommended.

Hope this makes sense

John Moody
 
John - Thanks for the comments. I agree the outside is far more critical and I'll spend more time on working that than I am the inside. My goal on the inside was functional as well as cosmetic - If the two halves have matching faces then I should be able to achieve a really nice seal between the two when they are closed. I don't know if this is even a problem (water?) during flight as it is?

I'm starting on the outside glass piece this weekend. I'm going to do this a bit differently. I'm going to do the lay-up and remove the whole assembly so I can trim the the lines neatly away from the plexi. I'm familiar with the electrical tape sanding technique but honestly am not a fan. I don't mind having a slight and uniform edge around the interior perimeter. My canopy shifted slightly as well (I wonder if Sika expands a little when it sets?) so great idea matching to two halves with flox. I'll copy that. I'm going to put a couple layers of duct tape over the canopy bow to ensure I have a little space to prevent the two halves from binding. Did you do this as well?

Thanks

Ken
 
Canopy/ Windscreen Joint

Ken

Sounds good. From memory I used about 4-5 layers of duct tape to allow an adequate gap after painting. Seems to have worked OK - no rubbing on paint but seals well.

One tip - takes a reasonable force to pop the canopy after glassing the windscreen bow even with a few coats of bondbreaker & relieving the joint by sliding a plastic spatula between the glass & tape. I tied a 1 in ratchet straps to each of the fwd bottom corners of the canopy frame. The straps sit flat under the skirt & then used a wood block on the VS spar to ratchet the canopy back . Easy controlled application of release force - no pulling or hammering required.

Hope this makes sense

John
 
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