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Sikaflex strength test

Kokemiller

Well Known Member
I bonded a 1" segment of powdercoated steel tubing to a 1.5" x 4" scrap of plexi with sika 295uv a couple of weeks ago for a test run. Today I set up a quick strength test and was amazed at the strength it has. I held the plexi in an open vise with the tubing hanging below, tied a 5 gallon bucket on to the tubing and began to fill with sand until failure. Put 50# in, still holding, added another 50# by setting full coffee cans on top of bucket. Still holding on. Went to get more weight to set on but it failed before I could set it on. With about 215" of total bond length, it should take up to 21500# to remove the plexi from the slider frame. This is enough to convince me it will work and will be bonding it today.
 
Thanks for posting this Kelley. I used sika on my -8A canopy and would do it again. There will be many people that will be dismissive of your test for various reasons. This stuff is very strong and flexible, the only thing that isn't proven out completely is longevity. Since this stuff lasts on boats being exposed to the sun everyday, I'm confident that it will hold up for a very long time on our aircraft.
 
Preperation and Primer

What prep (sandpaper grit) and primer did you use? and did you apply the primer (if any) it to both surfaces?
 
It failed...

...in the middle of the joint, you can see sika on both surfaces, no exposed plexi or paint.
I prepped it according to directions:
scuff with red scotchbrite pad
clean with 226 cleaner
prime p-coat with 206 g+p
prime plexi with 209
ran a bead on each side let sit

I will try to post pics when my IT girls get home from 4th and 6th grade this afternoon.
 
Good bonds!

That's the kind of 'failure' you're looking for :cool:
I also did a test piece, about 1.5" square of Sika holding a piece of aluminum to a piece of plexi. I just hand it to anyone who doubts the strength of the stuff to let them pull and twist it. It's still laying around my basement somewhere... I never got as scientific as you did :eek:
 
great data, thanks so much!

WOW - that is awesome. Good to see real world data not hyperbole.

The joint failing in he middle of the bondline is perfect, just what I'd want. Just curious - did you scuff the powdercoat first?
 
Sikaflex

Oh my gosh Kelley, your gonna fall out of the sky!!

Really, there's only one hole in my canopy. I'm not worried about the canopy accidently slamming shut or open. I'm not worried about expansion and contraction. I'm not worried about rivets loosening up. I'm not worried about the flimsy metal skirts vibrating and shaking the snot out of the works. And, I'm not worried about the canopy falling off. Definitely, I would do it again. How many hours do I have on this difinitive test? 13.2 TT. Yeah, it's four days old. I don't excpect to lose the grin for a long time.

Wish I had IT help at my house.

Steve
 
Yes, the powdercoat was scuffed. The strength of this stuff is unreal yet it remains pliable. When I started filling the bucket with sand I didnt expect to fill it, let alone start stacking on top. I'm not the least bit concerned about bond stength anymore. I think the hardest part will be to make nice looking fillets. Its not near as nasty as proseal to work with though.
 
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