Rene Bubberman

Rene Bubberman

Well Known Member
Hello Group,

Last night we finished our glued canopy and I just HAD to show you the final results!

0310canopypa7.jpg


If you want to have more details about the process, have a look at http://websites.expercraft.com/PHVII/index.php?q=log_entry&log_id=6287 and beyond
 
Its beautiful

I first saw the Sikaflex idea about a day AFTER I drilled the holes in my plexi, otherwise I wwould have dne the same thing.

Nice job!

Frank
 
Beautiful

Hi Rene,
Beautiful job there guys.....WOW. How did you get such a straight glue line? Tape it up first?

Really nice!
 
Looks great.. I just finished gluing the front part on mine.. really like it.. haven't got to the back window yet :) Will be reviewing the website to figure out how to clamp the back window in place..
 
Perfect timing!

Rene,

Thanks for posting your links! I'm in the process of finishing my canopy frame and will be glueing my canopy in a couple of weeks. I lwill definitely steal your method of holding the rear window in place. I have in mind the steps to take, but now I have your pictures to follow :cool:

In order to provide space for glue on the side frames, I put a 1/16" spacer between the side frame and the forward canopy frame. I also made a spacer for the skirt pieces, so the inside joggle of the frame is offset 1/16 inside the canopy for the entire length. I also adjusted the rear C channel width and height so that I have about a 1/8" space between the channel and the canopy for the glue.

Your canopy looks fantastic. I just hope mine comes close!
 
Be careful out there

It is of concern to me that many people may be using Sikaflex without first studying the recommended application specifications. I refer in particular to slider canopies with powdercoated tubular frames.

For instance it is relevant that you cannot use the same primer 209 that you use for the plexiglass on the powdercoat...you need another product altogether.

It is relevant also that the minimum bead width is 1/2" and the max is 3/4".

And also the absolute minimum bead height is 3/16".

I cannot see that in glueing say an RV7(A) slider that it is possible to obtain a minimum 3/16" bead height in all locations of the canopy without major modifications. If you do not achieve this minimum height (and +1/4" would be much safer) then you are inviting failure by shearing of the bead.

I see people talking about 1/16" and 1/8" bead heights. Where do they get these dimensions. I suspect these dimensions simply represent the largest gap that can be achieved without serious modifications to the canopy structure.

On a further note: the Sikaflex system is only as strong as the weakest link and it may also be possible that Van's powdercoating is the weakest link. As far as I can understand Van's has no written specification or QA program in place to guarantee the quality of the powdercoating it subcontracts out to various firms. If the 4130 steel is not properly prepared and passivated, and baked within a specific temperature range, then the powdercoat may have poor adhesion. How will you be able to tell without destructive testing. And if it passes today will it still pass in a year or so if the powdercoat suffers corrosion undercreep.

I don't want to spoil the party but there are many questions unanswered and I would caution builders from using adhesives to bond on their canopies without proper research and testing.
 
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bonded canopy

Wow! Rene that looks really, really nice. A very clean look. I'm planing to bond my T/U canopy on my 7a. I just haven' t decided which adhisive to use yet.
 
Sikaflex supplier in Europe?

Rene - nice job. A question. Have you found anywhere you can buy Sikaflex in small quantities in Europe? I had to get mine from Jamestown Dists and they were funny about shipping to the UK, though I have it here by a mystery route. If I need more, I cant find where to get it though.

Thanks,
 
Hey guys, thank you for the compliments! For Steve: I phoned Sika Europe and they gave me some locations for buying the stuff. Most of them were suppliers of boat-building materials. No big deal. If you need our address, drop me a mail.
As reaction to capt. Avgas: you are right of course. Be very careful applying the glue system, do exactly as the manual says, use enough surface, pay attention to gap size and use the right procedure for cleaning, scruffing, cleaning again and priming the surfaces. If in doubt call a Sika-distributor for advise (Viba in NL for instance).
Ok, it takes some serious research and planning but hey: the result is worth it!
 
Sikaflex

Rene - looks like you did a great gob. We did shear testing with Sikaflex(and NO I can not share data with you, please do not ask) and like Rene found, and Capt. AVGAS is saying IF(here is that big word IF again) you follow Sika's directions correctly, the canopy will fail before the bonding will. You CAN NOT put it on paint, you must ONLY put it on clean base material. And yes we used Sikaflex on our 9A tip-up, with over 240hrs of flying we are still happy we did.

Frank Thorman
N821BF
Flying for 2yrs
 
sika adehesive bead thickness

I used rubber hose washers to maintain 3/16" bead thickness and also where necessary to maintain contour of windscreen and canopy to frame and fuselage skin. When fitting (remove/replace ad infinitum), I marked the location of the hose washers on the canopy frame tube and the fuse skin so I had repeatability in the fit of the pieces up to the point that I cleaned everything up, scuff sanded and prepped/primed/installed adhesive. Worked great.
 
Maintaining 3/16" height...everywhere!

Bob Brown said:
I used rubber hose washers to maintain 3/16" bead thickness and also where necessary to maintain contour of windscreen and canopy to frame and fuselage skin. When fitting (remove/replace ad infinitum), I marked the location of the hose washers on the canopy frame tube and the fuse skin so I had repeatability in the fit of the pieces up to the point that I cleaned everything up, scuff sanded and prepped/primed/installed adhesive. Worked great.
Click to expand...


Bob, the canopy side skirt arrangement on the RV7 slider doesn't seem to allow for a 3/16" height bead. Did you attach the sides of the canopy with fasteners.

Also, if attached per plans, the canopy side skirt arrangement would not seem to allow for a 3/16" height bead at the front canopy bow where it meets the side skirt....how did you deal with this....did you taper down the bead height from 3/16" to something less at that location.

Also, how did you prepare the powdercoat...what primer did you use. And how do you know you have adequate adhesion of the powdercoat to the steel.
 
Powdercoat adhesion

Captain Avgas said:
... And how do you know you have adequate adhesion of the powdercoat to the steel.
Click to expand...
You'll never really know this, of course. It is the largest unknown in the entire process.
 
canopy side skirts

I used the adhesive on the front, center and rear canopy frame tubes. The canopy was cut slightly above the square side tubing. The canopy side skirts were already drilled to the square tubing. No holes were drilled in the canopy except for the latch handle tube. While the adehesive was setting on the canopy frame, I put spacers on the side canopy (with no adhesive) and cleco'd the side skirts to the frame. The spacers set the "fit" of the canopy. Once the adehesive had set on the frame, I applied more adhesive to the sides of the canopy and installed the side skirts using countersunk structural pull rivets. The powdercoat was scuffed with 60 grit and the wash, primer and adhesive was applied to that surface. I did testing of powdercoated tubing and Sika (along with other bond tests) to determine it would hold well. It did. As far as the bond of the powder coat to the steel, I guess I'm a trusting sort. There are no indications anything is coming loose yet. Everyone has to determine their own comfort level, and I have made my decision and moved on. The installation allows easy access for inspection and it the bonds all look excellent and the canopy and windscreen are as solid as Time may prove me wrong, but I am more concerned over a lot of other things failing before being concerned my canopy will let loose after being bonded...
There are approximately 210 lineal inches of bond surface on the slider frame on my 7A. There are about 120 lineal inches of bond surface on the windscreen. If you insure a 1/2" wide bead, that's a lot of bond surface. Some will prefer screws, go with whatever turns your crank.
 
Correct primer, correct bead

Bob Brown said:
The powdercoat was scuffed with 60 grit and the wash, primer and adhesive was applied to that surface.
Click to expand...

Sika specifically says not to use the Sikaflex 209 plexiglass primer on powdercoat. The correct primer for powdercoat is Sikaflex 215.

Also I don't think most builders fully understand the importance of having a MINIMUM 3/16" bead height...everywhere. Plexiglass will expand at a considerably different rate than the metal it is adhered to. A tall (and not too wide) bead allows the bead to flex sideways and thus accomodate this differential movement. A short (in height) and wide bead cannot flex and therefore exceptionally high shear stresses are transmitted to the metal/bead and plexi/bead interfaces. If the temperatures, and therefore the differential movement, become great enough there can be a failure at the interfaces. It is not a failure in tension...it is a failure in shear. And once it starts anywhere then, like a crack, it can easily propagate.
 
I just read their site and they specifically say that 209 is suitable for thermally or chemically cured coatings, and specifically mention powdercoat.

Clean with 226, after abrading, and then apply 209.

just visited their site which has gotten better.
 
Huge Area

Bob Brown said:
There are approximately 210 lineal inches of bond surface on the slider frame on my 7A. There are about 120 lineal inches of bond surface on the windscreen. If you insure a 1/2" wide bead, that's a lot of bond surface. Some will prefer screws, go with whatever turns your crank.
Click to expand...
Well said Bob. I was going to make this point but you beat me to it. The surface area is huge. The critics make it sound like we are hanging our lives on one square inch of elmer's glue and hoping for the best. I glued my canopy and am happy that I did it.

Nice work Rene, here is how mine turned out:
20051020canopyonfuselage5rj8.jpg
 
Thorough research.

It is apparent that those who have used adhesive to fix their canopies have done a very thorough job in researching the application of the adhesive.
They certainly have my respect and I would not question their results.
However, I think it worth pointing out that if it were done slap-dash and the adhesive fails, you are likely to have more than just the 'Wind in Your Hair' to contend with, as you are likely to be without a Vertical Stabliser.

Pete.
 
Final queries before I glue my canopy?

I have resurected this thread because it is mostly from people who have used Sikaflex or have a positive interest in it. I hope it stays that way. There is another current thread for the doom mongers.

I have read most of the stuff that has been posted, but before I go ahead I have a couple of queries that I would welcome comment on, from people who have done this:

1. I plan to put the main 'fixing' coat all the way around, except for some 4" long spaces where the hose spacers/clamps will be. My question, when I come back to do these 4" sections after the thing is attached to the frame, will it be practical to get the primer into the 3/16" gap between the glass and frame? I guess this is a question of how runny it is.

2. I plan to do the 'cosmetic' coat at the same time I complete these 4" gaps. Is it appropriate to prime the cured Sikaflex when I add a cosmetic coat, or does it bond to itself just fine?

3. I am wrestling with which way up to do it. (The canopy, not me!) Because the -4 canopy is a one piece, I can not reach in through the end. I will have to set it between two stands quite high, so I can walk in from underneath. I presume to get a good finish on the visible / upper joint, it needs to be the right way up? Gravity will presumably not help the lower surface? I guess I am asking how much it oozes?

4. On the -4 canopy there is normally, a very small fiberglass fairing. Once Sikaflex is cured can it be sanded and shaped? I think I have seen a picture of this somewhaer but cant now find it. Is it suitable as a replacement for the glass? It will of course get painted.

Thanks so much.
 
questions

Hi Steve,

1) The primer is very runny, and should be very easy to get into a 3/16" gap.

2) I have not tried to bond it to itself, so I can't tell you.

3) It didn't ooze for me at all. It's like peanut butter.

4) It dries pretty stiff, but still flexible. I doubt you can sand it, but I have not tried.

To get it to look really good, I'd plan on doing it right the first time, which takes quite a bit of care, or a technique I didn't quite get. Mine looks "O.K.", but not great. There are hints on my site related to the cosmetics. Also, Eric's got some great hints here:

http://www.rv8.ch/files/RV-8CanopyGluingProcedure.pdf
 
Overlapping Sikaflex

Mickey, thanks for that.

Reading through the various sources of Sikaflex info., most people talk about bonding in two stages. First to fix it, then cosmetics or to fill in gaps where clamps and spacers were located. This means that inevitably newer 295UV is going to meet up with not quite so new 295UV.

QUESTION: Anyone know how to maximise the bond between these two coats of the material?
 
Jim,
Nice looking canopy! Did you make any adjustments on the cabin frame during construction to allow for the thickness of the Sikaflex? I really like the combination of gluing and screwing that you used, but my cabin frame is built to plans, and it seems that the width of the cabin frame would have to be made smaller on the order of twice the spacers (bead) width less. Or am I missing something? Thanks
 
Spacing Plexiglass

Hi Rocky,

My frame was also built to plans.

I taped rubber hose washers on canopy bow and under front bottom edge where plexi touches the cowl while trimming to final size. This created the 3/16" gap needed. Plexiglass canopy has plenty of excess material on the sides to allow for the repositioning that occurs.

The plexiglass is glued to the frame side rails but I made no great effort to maintain spacing on the sides. (Note the clamps.) Instead I ran an additional bead of Sikaflex along the bottom edge of the plexiglass along the side rails. And, of course, after everything had set up I added the "chicken" bolts along the sides per the plans.

Hope this helps.
 
the sequence

Guys, there is something that I must be missing.

Mickey put small blobs in to adhere the canopy in place, then came back later to fill in the rest. Eric put in most of the sikaflex then came back the next day to do the cosmetic coat. I am assuming, which is dangerous, that the issue of doing the sikaflex process in two days revolves around the time limit of 30 min to 2 hours between the primer and the 295.

Is it not possible by priming and applying the sika 295 a section at a time?

I plan to use 3/8 inch spacers to hold the canopy off the frame while I apply the sikaflex. It seems possible to get the primer between the two surfaces easily with that distance of "standoff".

Once again, is there something that I am missing? I am ready to glue, but I want to make sure that I have a complete understanding of the options before I begin.

Tony
 
Where does it say you have to apply it within 2 hours? I just looked at the instructions again and I see no reference to it. It does say to wait 30 minutes for primer to dry...
 
2 hour limit

Radomir,

I got that from the very detailed writeup done by Eric Wolf which can be found on Mickey Coggins website.


"Other builders have applied the glue in a few blobs first, then coming back the next day and filling/smoothing. This works OK, but the instructions for Sikaflexspecifically say that the glue should be applied within 2 hours of applying the primer."

I just took a quick look at the sikaflex 295 and primer containers in my shop. I did not see a reference to the 2 hour limit on the product. The instructions on the product did say that there was a more detailed data sheet available from sikaflex.

Perhaps Mickey, Eric or Jim can chime in here on the topic.
 
Ah, I think I found it.. I believe this is what they're referring to and explains the reasons for the "2 hour window:" (may or may not apply to us)

"Waiting too long, however, to apply the adhesive risks having the bonding surface contaminated with dust or debris. Therefore, it is recommended to apply Sikaflex ? within 2-3 hours of the primer application."

This is under generic Sikaflex suggestions for best bond. There's no such reference specifically for 295 (and maybe more importantly, no *requirement*).
 
Radomir, I am in the middle of using this stuff. It is not clear to me that the upper limit on the primer is ONLY because of dust/contamination. See page 3 here -209N. I think this is putting an upper limit of 24 hours on it, though in practice I had done what I needed to do in the first instance, inside the two hour window. (I am very uncertain as to what Sikaflex would advise after 3hours if you could control contamination.)

With the canopy in its second day of setting, my questions are these:

1. What is the best way to fill in the voids where the clamps were, and how to add more Sikaflex on top of yesterday's Sikaflex?
2. Should I remove old primer and put on new where the old is showing, or should I put primer on top of old primer after cleaning again?
3. Should I put a layer of primer on old Sikaflex after cleaning, when I want to add more Sikaflex.

I have not read anything about this yet, nor had a reply to my email to Sikaflex. Anyone know these answers?

You can see what I have learned so far if you follow this link to 23rd May '07 entry.
 
Steve, just fill it with additional adhesive.. I do not believe that trying to add more primer is OK. Just adding additional adhesive worked for me.

I put majority of the bead during initial installation.. but left a little bit of space to fill for cosmetic purposes.. it worked well.. my canopy has been through cold and hot "soak" sitting in the garage... I'd guess temp range over the past year was between 10 and 110 degrees F.. no problems..
 
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