SikaFlex and Windscreen attachment

Decided to go the SikaFlex route after numerous amounts of input from a lot of experienced RV builders.

Question for experienced SF installers: On the windscreen, how did you attach to the roll-bar? To the deck? I have seen a lot of step by steps on the canopy section but little on the windscreen. I find a lot on the fiberglass fairings etc, but little on the actual SF attachment of windscreen.

Did you use the screw method on the roll-bar with SF fillet or just SF? Any other methods.

If you have a site with photos send me a link.

Trimming this weekend as I listen to Auburn LSU game, glueing next week.

Thanks,

Sandy

***Caveat - I built an RV-7***

My slider canopy and windscreen have a grand total of ZERO screw holes.

The canopy (slider portion) is sikaflexed all the way around the perimeter and along the fore-aft slider bow.

The windscreen is held in position by about five aluminum tabs pop-riveted onto the forward turtledeck. These tabs are not riveted/screwed to the plexiglas. They simply press against the plexiglas to hold position. Fiberglas is then used to attach the plexi to the forward turtle deck, completely covering and hiding the tabs. The windscreen is sikaflexed to the roll-bar bow. I think some people sikaflex the turtledeck/windscreen intersection as well, and then fiberglas over the sikaflex.

The advantage of using Sikaflex is that you eliminate stress points (screw holes and rivets) in your canopy. With all of the stories about screw holes developing cracks - even with the utmost preparation and care - it just makes sense to make your canopy as stress-free as possible. My canopy has one hole in it - the hole for the canopy latch handle.

What Scott said.

Even considering fixed attached with the sika system defeats the whole purpose. It should NOT be used as a filler. Its way too heavy and expensive for that.

Its an adhesive. Adhere it to the rollbar and skin.

Sika on windscreen to skin interface?

Kahuna said:

Its an adhesive. Adhere it to the rollbar and skin.

Click to expand...

I completed the Slider using Sika (no mechanical attachment).

For the windscreen / skin interface - it there any advantage to using Sika? You'd still fibreglass over the Sika, right? So I assume a Fiberglass-only joint is lighter and adquately strong.

Love to hear pros & cons from experienced builders.

Sika on windscreen

At the roll bar attachment, I made 1/8" shims to get the windscreen to line up perfectly with the canopy, then used Sikaflex only to bond to the roll bar. Same as canopy frame, 2-step process. First, put just enough to get it glued on between the shims, then the next day, pull the shims out and do the whole area, with nice fillet.

On the forward skin, I put a modest Sika bead between the windscreen and forward skin. This was mainly to just get it fixed in position with no stresses. Then the glass fairing is built up over it, which of course is the real structural attachment. The Sika on the skin is really to just get it held in the perfect place so it doesn't move around while you are laying up the glass.

By the way, mix black die into the epoxy for the glass fairing.

Then, a final touch, on the inside of the windscreen along the joint with the skin, I placed a 1/4" neoprene tube in the corner as a trim moulding. It is regular vacuum line tubing from the auto supply store. I glued it in with a few drops of crazy glue. It adds a very nice finished look to the inside of the windscreen.

I agonized over what to do with the windshield and Sika too. I decided to use the Sika on the inside of the windshield. It is a little heavy compared to the other possible options as mentioned, but I put a fillet on the inside of the windshield and it turned out nice. I know the windshield is not coming off--that stuff is bullet proof

Then on the other side (the outside), I am in the process of doing the normal fiberglass layup for the fairing. I did not want to put fiberglass over top of the Sika (wasn't real familiar with the bonding of the fiberglass to the Sika). The windshield is kind of what seperates the Sika from the fiberglass since each one is on each side. I would do the same thing again, but it hasn't flown and it's not completed yet.

Post to us what you decide to do if you don't mind.

I used SIKA on both the canopy and the windshield.
I used a generous bead for the windshield, and don't intend to add the fiberglass, that windshield is bonded securely. It looks fine without the fiberglass, but could use some filling at the forward lower edge of the canopy.
If I do decide to fiberglass the windshield surround, I doubt I would do the top portion over the roll bar. I'm not sure how it helps secure the windshield, but I'm pretty sure it adds a fair bit of aerodynamic drag. It might be good at keeping the rain out.
I like the fiberglass lay up over tape, where you pop it off after the lay up, and do the finish work away from the windshield (to avoid windshield damage) then bond it in place.
Disclaimer: I haven't flown yet!!

SikaFlex

I glued to the deck and the roll bar. Then I finished the outside using glass. Did use some of the clips to hold things in place then glassed over them.

Caution with the advise. I'm an LSU grad.

Ken

One other question: spacers for windscreen

Thanks for the replies.

Here is one last question re: spacers. The spacers are needed to create an expandable joint (1/8"). So on the windscreen to deck attach, did you place any spacers under windscreen (between bottom edge of plexi and the aluminum)?

I read of one man who traced the contour of the windscreen then laid down a bead on that line and just pressed it into the SF (primed & all).

The reason mainly for the question is related to the trimming I am doing now. Adding spacers would affect the trimming forward.

Thanks,

Sandy

I had 1/8" spacers all around.

Sikaflex

In looking to buy Sikaflex, I find different types. Can someone be specific on which Sikoflex? Thanks

Sikaflex 295 UV

SIKAFLEX UV295 comes in Black & White. Black is preferred. I accidentally bought some white, so I have both. I guess I'm a test case now.
I've been flying 2 years, still don't have the fiberglass around the windshield.
SIKA Is great, but it weighs a little more & is expensive.
I have a 1" crack (stop drilled) from the hole for the latch. The canopy shifted when I 'final' assembled it. Bummer.

Yes ... 295UV
+ cleaner and primer..
see here..
https://www.google.com/?gws_rd=ssl#q=sika+206+vansairforce+site:www.vansairforce.com

I ended up buying for canopy.. but was already drilled, so I riveted. Planning on sika'ing the windscreen because mine like scsmith didn't line up with the canopy and needs to come up.. but is a larger gap.. maybe a 1/4"..

merrittsupply.com had good prices quick shipping ( no affiliation)


I will probably have some left over especially primer 206 and cleaner.. so if someone close by .. West NC../ N. Georgia needs some.. let me know.

Aktivator Rimper, Sikaflex 295UV

All you Siki guys. Wow, what a challenge, did you use Aktivator & Primer 209D? I am so confused over this product. I bought the Aktivator 100, primer 209D and Sikaflex 295UV. Aktivator says 10 minutes to 2 hours, primer says nothing, 295UV says tack fee 1 hour, 5-8 days cure. How the heck do I do this? Spacers, tack, then full, how do you handle with all the "times" involved. Also, I have a call into Sika Corp, no returned call yet.....

dvalle,

Don't Panic !

Having done a 7 tip up and an 8 slider, there are no real problems, but your prep must be meticulous and you really need help when doing it.

1. The whole canopy must fit - well !
2. Test fit with ratchet straps ($15 Home Despot ones are fine) to make sure it doesn't bulge anywhere when you put pressure on - you don't need much btw, just enough to make it all fit - the Sika does the rest. Make sure you have target reference points on the structure and the canopy - you will place this once and once only !
3. Mask where you want the primer and scruff up the canopy with red Scotch so it is completely opaque. Scuff the structure as well and mask accordingly.
4. Spacers - some do, some don't. We didn't and have had no issues. The spacers ensure an 1/8th bed, if you pipe correctly and don't apply too much pressure, that is what you end up with.
5. Get ready......
6. Practise the place and settle down onto the structure.
7. Figure out how to cut the end of the nozzle to create a triangular fillet - it isn't difficult and you may need to practise on a spare silicone tube but you can pipe a very nice triangular fillet.
8. No coffee. Don't want any caffeine shakes for the next bit.
9. Nearly ready.
10. Clean all surfaces - you can use their product or good panel wipe, very similar.
11. Now you become time restricted as you are about to start. Brush on the primer - it is the only thing the Sika will stick to. It flashes off very quickly - dries almost instantly. You have a couple of hours now or else you need to re prime. Prime both surfaces.
12. Get piping the adhesive on - just onto structure, just where it will touch.
14. Set the canopy down carefully, don't wiggle it, don't squeeze too hard.
15. Set your straps and make sure your fit is OK.
16. Now using a standard end nozzle, pipe a fillet on both sides of the structure in one fluid movement.
17. Using a tongue depressor of a suitable radius (insert this bit into step 2) dress the fillet again in one smooth movement. Your masking should be lined up with the edge of where your fillet will end and no more.
18. Go for a well earned beer and do not, I repeat DO NOT fiddle with anything.

After a couple of hours, it will have taken a first set and you can gently start to remove masking and using a sharpened popsicle stick with rounded corners, start scrape away the excess Sika that will not adhere to structure unless it is on primer.

Leave for a day or so and bingo - perfect canopy !


To the others - if I have missed a step, or if you wish to alter slightly, chime in please, that is how we did ours and got perfect fillets and edges on both.

Good luck !

Thanks for the great reply...and not to panic....I do have a question. I was told to use all three (mentioned previously). You stated clean all surfaces, use their product? Would that be the Aktivator (for cleaning)? If so, what the heck is so important about using it "in one direction" per the instructions? 10 minutes to 2 hours?

You also state only a couple hours on the primer? The primer can is the only thing that has no directions.

FYI-Sika Technical Support never called me....

I am in the Hickory area and will be gluing my canopy before cold weather so Inwould be interested in any leftovers.

pfactor said:

Yes ... 295UV
+ cleaner and primer..
see here..
https://www.google.com/?gws_rd=ssl#q=sika+206+vansairforce+site:www.vansairforce.com

I ended up buying for canopy.. but was already drilled, so I riveted. Planning on sika'ing the windscreen because mine like scsmith didn't line up with the canopy and needs to come up.. but is a larger gap.. maybe a 1/4"..

merrittsupply.com had good prices quick shipping ( no affiliation)


I will probably have some left over especially primer 206 and cleaner.. so if someone close by .. West NC../ N. Georgia needs some.. let me know.

Click to expand...

They want to sell their cleaner/aktivator.

You need a good clean substrate for the primer to adhere to, that is all and it is the same as any primer prep.

The primer is strange stuff, it bonds with the Sika adhesive, but it has a defined time, around 24 hours I believe, longer than the 2 hours I stated.

Have a look here - this is good.

www.cruisersforum.com/forums/attachment.php?attachmentid=29490...

I used short peices of slit garden hose for spacers around the canopy, and caulked the canopy to the frame. I left gaps around the spacers. When the SIKA had set up, I removed the spacers and SIKA'd the gaps. It was a few days later, but the bond seems good where I filled these spacer gaps.
Install a shim around the canopy latch hole, that was my only serious mistake. I ended up with Plexiglass to steel contact, and a small crack developed, which I stop drilled.
I had better luck removing the masking (electrical) tape as soon as possible. SIKA starts to set up on the outside (skin over) quickly.
This was particularly important when I installed the skirts, because you have to put the SIKA on the canopy,then install the skirt over it and press it on until the SIKA squeezes out. I did drill a few holes thru the skirt & frame, then used clecos to pull the skirts down and hold them in position.
The SIKA that squeezes out ends up on the masking tape. Peel this off right away to get a perfect edge seam.
Go back inside and use the caulking gun to filet the canopy frame tubes to the skirt. I used a few temporary shims to hold some areas out. That helped maintain the desired shape until the SIKA set in a few days.

the Sika cleaner appears to be an expensive can of rubbing alcohol. If I were to do it again I would just use alcohol. Like others I also did my 8A canopy with zero holes and zero rivets, but also bonded the windscreen fairing using Sika, hoping to avoid cracks in the layup on the sides of the fairing that we see so often later on. Now I have a thin layer of flexible sika between the fairing and the plane (I finished the fairing off the plane). Granted, it's not a seamless smooth transition, but neither is a crack later on and I think it still looks pretty good and fits in with my warbird theme.