Sikaflex spacer question

[Steve Ashby]

I am about to glue my 8A canopy (not to be confused with an 8 canopy, which is completely different using new Sikaflex, cleaner and primer. I caved into peer pressure to pitch the expired stuff.

I am using the popsicle stick method of spacing the plexi from the frame for the right gap to maximize adhesion. I drilled through the plexi, through the popsicle sticks and into the canopy frame so that I could cleco the canopy onto the frame.

Here is my question: When I glue the canopy onto the frame, will I have to do something to the popsicle sticks to keep them from sticking? I will have to pull them out after the Sika dries and I am concerned that the popsicle sticks might not pull out cleanly (or even break off).

For those who have glued before, what is the deal?

Thanks a million!

[scsmith]

Hi,

So, here's what I did. On the first application of the Sikaflex, just put it inbetween the spacers, down in the gaps and partially fill the area, but do not build up the full fillet. You just want to get enough to get a good bond. Do not put any Sikaflex near the spacers.

Now, wait one day. If you can cover everything up with a light drop-cloth to keep dust out of the area, that's good.

OK. After 24 hrs, the first application is cured. You now pull the cleco's out, and the spacers. They will come out clean, because you did not get any Sikaflex on them. Now, you can fill in the gaps where the spacers were, and then proceed to build up the nice fillet of material that you will screed off with a radiused tool ( I used tongue depressors).

This process lets you make one nice smooth fillet all at once. Resist the temptation to build up any of the fillet on the first day.

Lots has been discussed about the guideline that the Sikaflex should be put on the primer in the window between 2 hrs and 24 hrs. and whether more primer needs to be added after waiting 24 hrs. I found in the Sikaflex literature that the primary concern was dust accumulation, not any aging problem of the primer surface. I found in tests, and in my actual canopy, that the adhesion to the primer is perfectly normal when applied after 24 hrs. Indistinguishable from the bond from application at 2 hrs. So my advise is not to worry about that.

Good luck,

Steve.

[whittfic]

I used small sections of nylon garden hose (1" or so in length) split lengthwise and 'wrapped' around the canopy frame tube on my RV6. Applied the first bead of Sika to hold everything in position. When cured the garden hose spacers came out relatively easily and the resulting gaps were easily filled when applying the finishing beads on either side of the tube. Worked like a charm.

Clive Whittfield
Auckland
New Zealand

[gereed75]

I like the elegance of both of these suggestions. Check your PM for an alternative.

[Jamie]

Steve:

I have no useful information to provide because I didn't glue my canopy on, but it sure is good to see you back on your project!

- Jamie

[dpansier]

"I am using the popsicle stick method of spacing the plexi from the frame for the right gap to maximize adhesion. I drilled through the plexi, through the popsicle sticks and into the canopy frame so that I could cleco the canopy onto the frame."


I did something similar to this but used small diameter "O" rings.
I drilled through the plexi and the frame like you mentioned for location purposes and placed "O"rings between the plexi and the frame held in position with clecos.
The "O"rings remain in the assembly with the Sikaflex.

[bret]

Originally Posted by dpansier

"I am using the popsicle stick method of spacing the plexi from the frame for the right gap to maximize adhesion. I drilled through the plexi, through the popsicle sticks and into the canopy frame so that I could cleco the canopy onto the frame."


I did something similar to this but used small diameter "O" rings.
I drilled through the plexi and the frame like you mentioned for location purposes and placed "O"rings between the plexi and the frame held in position with clecos.
The "O"rings remain in the assembly with the Sikaflex.

I vote for O rings. So much info in here!

[gereed75]

nice idea !!!!

[Lars]

Yet another suggestion... I started by making spacers cut from vinyl tubing. Used different wall thicknesses so I could shim appropriately, since the slider bow for my 7 was, shall we say, less than perfectly formed.

Then I saw a suggestion by someone who had made spacers from the rubber tubing used to hold screen in a screen door. He cut short sections from it, then used superglue to hold them to the frame. Then applied primer and 295UV over them, leaving them in place.

I decided to do a variation on the same theme, only since I needed varying thickness spacers, I just cut little squares out of the tubing sections I already made. Stuck 'em on with superglue, primed, applied Sika, etc.

Several weeks later I had the "opportunity" to learn how well the Sika had adhered to my spacers when I joined the Cracked Canopy Club by dropping a pair of vice-grips directly above where the pilot's head would be. I used a razor blade to slice the Sika and get the cracked canopy off, so I could re-use the frame. Using pliers, I tugged on stray pieces of Sika in places where I knew I had spacers. Some spacers pulled loose from the canopy frame, taking gray powder coat with them. Others ripped in half. I didn't see any evidence of adhesive failure (Sika pulling off the spacer, leaving the spacer intact). Based on what I saw I don't believe that leaving small spacers in place results in compromised structural strength, though obviously it could take years before that becomes apparent.

When I did Canopy 2.0, I used the same technique. Saves a little time since you don't have to go back and fill in after removing spacers.

[timandmeli]

Steve,
I second the motion of "good to see you back on project". I met you in Evergreen shortly after I started my 8A and you loaned me tools to back rivet my wings. Seems like a long time ago. My "I can finish in three years" will have doubled by the time i actually do. Oh well life gets in the way. Press on.

Tim Pethel