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Sikaflex Spacers

Tsabean

Active Member
Preparing to glue canopy to frame (RV4) using Sikaflex. I’ve read most of the threads I could find on the subject but I’m still unsure of how to go about using spacers.
I’ve seen mention of using garden hose and removing it after Sika has set up.
Anyone have any photos of this, or any, method of spacing?

Thanks, Tom
 
spacers

There are several good methods that will work. I used garden hose but newer methods using rubber washers or even dabs of sika that have dried seem even better. Main thing is to leave a bit of a gap, and clamp the canopy in the right place. Then you can go in to glue it in place, and come back with a 2nd pass and make it beautiful. If you use small rubber spacers you don't need to remove them. Obviously something like rubber hose will need to be removed.

While you have the canopy off, be sure to smooth and polish all the edges to relieve any stresses that might eventually cause a crack.
 
Spacers

I used round 1/8” screening bead that I bought at the local hardware store. Can cut them and leave them in.
 
Stresses

I used a minimum along the fore and aft bow as the natural curve required. My feeling is every clamp on the canopy is two stress points. One either side. I used spacers where needed but I clamped the sides using a section of angle each side. The fore and aft bow areas were allowed to fall into a natural bend. One hand clamp fore and one aft were all I used to cure.
 
Tile spacers from the aviation aisle at Lowe’s worked for me. You can cut these and get four spacers per piece. Space them, super glue them to the frame then when you lay out the Sikaflex bead and clamp the canopy or windscreen in place, you’ll never see them.
 

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Clarify

Just to clarify, I am doing the final trim now.
It seems to be, the outside edge of the plexiglass is to be even with the outside edge of the fore-aft bows.
This means the plexiglass is not spaced away where the aft hoops and the forward hoop are welded to the for-aft bow, Correct?

So the only 1/8" spacing (gap) would be at the top. And somewhere down the sides of the front and aft hoops, the spacing will need to be reduced?

Correct?

Thanks for the feedback.
 
Just to clarify, I am doing the final trim now.
It seems to be, the outside edge of the plexiglass is to be even with the outside edge of the fore-aft bows.
This means the plexiglass is not spaced away where the aft hoops and the forward hoop are welded to the for-aft bow, Correct?

So the only 1/8" spacing (gap) would be at the top. And somewhere down the sides of the front and aft hoops, the spacing will need to be reduced?

Correct?

Thanks for the feedback.

Yes this is correct. I think people also get too hung up on the spacing. Keep in mind the tubes you are gluing to are round so there will always be some pretty good thickness in your beads, it just won't be directly above the apex of the curved tubes in some spots.
 
Can't speak for the -4 or -9 canopy. Here's a picture of how the spacers work on an -8 canopy. For Sikaflex 295, if I remember correctly, the entire seam has to be spaced. That information is backed up by their installation guide. Here's an excerpt straight from Sika:

BOND LINE THICKNESS
After it has set, the adhesive remains flexible. However, if too thinly applied, the adhesive may shear due to the changes in dimension caused by differences in thermal coefficient of expansion between the glazing and the superstructure and also the natural flexing between the glazing and the window frame in the varying sea conditions. Sika’s dimensioning guide provided adjacent to the appropriate procedures determines the depth of spacers required to be placed within the adhesive to keep the distance equal to or greater than the minimum depth required to ensure the reliability and longevity of the adhesive and the bond.

In theory, this provides a flexible bond between the canopy and the frame and if properly fit, should eliminate any stress points.
 

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I used small pieces of basswood (about 3/16" square) superglued to the front bow when fitting the windshield on my slider. Was easy to sand them thinner as needed to get a flush fit to the canopy.
Stewart Willoughby, 6 painting
 
Don't !

They are not needed....

If you get a new windshield on your car glued in, they don't use spacers.

Pipe the triangular fillet on, sit it down, strap it lightly and go for a beer ;-)
 
Don't !

They are not needed....

If you get a new windshield on your car glued in, they don't use spacers.

Pipe the triangular fillet on, sit it down, strap it lightly and go for a beer ;-)

"Place spacers in position". 1st line from the manufacturer of the product. :confused:

This is not a glass windshield, that's why you use the marine acrylic instructions. They have a different product for glass. Spoke to them at length prior to gluing mine on and after 5 years, 400 hours in extreme hot and cold temperatures, no cracks, no separation, no issues.
Just my 2 cents worth, so you get what you pay for.
 

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Check my Kitlog pictures

Check out my Canopy section of my Sika canopy installation. I used 1/2" wide pieced of 1" OD clear vinyl tubing from Lowes. Put the Sika right up next to it, let it cure, removed the tubing, filled in the gaps and made a nice skim coat. One trick is with Sika is that you only get to smooth it with one pass. Don't be tempted to try to do a second pass, you will make a mess of it. It can be sanded after it fully cures.
 
I used round 1/8” screening bead that I bought at the local hardware store. Can cut them and leave them in.

Or if you don't put any Sika primer on these, you can pull them right out after the Sikaflex hardens. I did a first pass with the sealant using the screen bead spacers, and then did a second final pass within 24 hours to make it all pretty and pull off the masking tape. Still looks great after 6+ years and hasn't had any issues with holding strength.

For the lower sides where the spacing is only something like 1/32", I used some heavy test fishing line that was superglued in to keep some room for the Sikaflex. This keeps you from squeezing out too much of the sealant and makes it a consistent thickness where the lower skirts don't give you much space between the aluminum and plexiglass.
 
"Place spacers in position". 1st line from the manufacturer of the product. :confused:

This is not a glass windshield, that's why you use the marine acrylic instructions. They have a different product for glass. Spoke to them at length prior to gluing mine on and after 5 years, 400 hours in extreme hot and cold temperatures, no cracks, no separation, no issues.
Just my 2 cents worth, so you get what you pay for.

+1

I used sika on my 10 windows and they are adamant on having a minimum thickness of sealant between the acrylic and the frame for longevity. How you achieve it is your business, but things like clecos will likely squeeze out too much without spacers.
 
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If your canopy fits correctly, if you pipe the triangle nicely, if you don't squeeze the breath out of it, you end up with perfection......

Twice...

RV7 - 500 hours

RV8 - 400 hours.

It's just gluing plastic on, it's not rocket science. And no, I didn't use Proseal on my trailing edges and they are still perfect after 10 years :p

And heck - I don't use full fine prop for landing because 2300 is just darned perfect.

And I don't lift the tail...

And I just got a tattoo at 62, so don't push me - Right ;)

And I have just done 2000 posts - so there !


Tee Hee
 
It's just gluing plastic on, it's not rocket science.

No offense Mike but why would you completely disregard the specific instructions of the product manufacturer?

Did you use the Sika 209 primer or something else because it’s “not needed” or “it’s just plastic”?

Here’s one of the Sikaflex 295UV guidelines:

BOND LINE THICKNESS
After it has set, the adhesive remains flexible. However, if too thinly applied, the adhesive may shear due to the changes in dimension caused by differences in thermal coefficient of expansion between the glazing and the superstructure and also the natural flexing between the glazing and the window frame in the varying sea conditions. Sika’s dimensioning guide provided adjacent to the appropriate procedures determines the depth of spacers required to be placed within the adhesive to keep the distance equal to or greater than the minimum depth required to ensure the reliability and longevity of the adhesive and the bond.

Notice where it says “ if too thinly applied, the adhesive may shear....”

If you use the required spacers there is no way you can end up with a section where it’s too thinly applied.

Congratulations on your 2000+ posts. ;)
 
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