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Old 07-22-2018, 09:35 AM
1bigdog 1bigdog is offline
 
Join Date: Jun 2014
Location: Markham, Ontario, Canada
Posts: 149
Default a couple questions about the sika process

I'm getting the canopy all set up to do sika instead of rivets.

I was wondering about a couple things.

If I'm reading correctly all the applications I've seen (in the forum) have been to prime, then set the canopy frame in place, strap everything then squeeze in the sika. I was wondering if anyone has tried using the "automotive" method which would be to sika the canopy (or the frame) first, THEN drop the frame on the canopy, strap everything down. The obvious advantage is that the squish out is probably a better way to set it even if you want to add more sika later to improve the filet. Further, as to blind setting the acrylic/frame in the right place you have the hole front middle for the latch and can probably set the aft by pre-cutting notches where the square tube and the acrylic are finalized later. Yes, no ???

The other question this leads to is about the spacers. If you use the automotive method I'm not sure why spacers would be required. With round tube against a flat acrylic you achieve the minimum sika thickness almost instantly as the tube curves away from the flat surface. You may have some direct contact points but everything else would be as Sika intended (squish down automotive method).

Thanks for all your insights in advance.
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Old 07-22-2018, 09:59 AM
rv8ch rv8ch is offline
 
Join Date: Feb 2005
Location: LSGG
Posts: 2,299
Default Sika methods

I considered the auto method but found that at least on the 8 getting the canopy in exactly the right place took quite a bit of fiddling, and I can't imagine doing that with all the glue there and the time pressure, and only one pair of hands. The 9 might be easier.

About the thickness, my understanding is that since the canopy and the frame will have different thermal expansion rates, too thin a layer of sika will cause it to tear.

Good luck!
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Old 07-22-2018, 04:47 PM
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maniago maniago is offline
 
Join Date: Aug 2014
Location: Bowie MD
Posts: 568
Default

Sitka is strongest when its in tension with itself and surfaces that are parallel. As you move around the edges of the tube, it turns into shear stress. Not sitkas strong suit. The min thickness should be considered absolute - if you have less than this, you want it in as very few places as possible.

Just my .02 but why mess with what works? Put in your spacers, squeeze in blobs in places, let that tack up good then go back and do full tube width all around the frame. It works. Just like caulking your bathroom tub. You wouldnt put caulk on your tub or walls and then try to set it in place, would you?
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Last edited by maniago : 07-22-2018 at 04:51 PM.
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