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What canopy adhesive to use?



 
 
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  #11  
Old August 16th 17, 03:40 AM posted to rec.aviation.soaring
Scott Williams
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Posts: 198
Default What canopy adhesive to use?

On Tuesday, August 15, 2017 at 10:45:07 AM UTC-5, Eric Munk wrote:
L285/L335 with microballoons was used by a large number of german and
polish manufacturers. Poles usually apply Aerodux and grind that down as a

primer to make the epoxy stick to the plexi. Alternatively, using a
polyesther
instead of an epoxy makes for a stronger joint but significantly shorter
potlife
(minutes not hours). I have seen various other modern kits used too. Some
with great succes.


At 15:28 15 August 2017, Steve Leonard wrote:
On Tuesday, August 15, 2017 at 10:04:50 AM UTC-5, LongJourney wrote:
=20
After reading some RV builder sites, I'm thinking what was used on my

can=
opy was Proseal, not Sika.

Pretty sure it is NOT Proseal. When that stuff cures, it is stuck. It
doe=
sn't seem to deteriorate with heat, moisture, UV exposure, or anything.
Ye=
s, it is a black (or very dark gray), sort of rubbery when cured

adhesive.
=
But from my experience, it will not fail. The plex will break, or the
ste=
el tube frame can rust away, but the Proseal will not separate.

I was once told that 3M 5200 is great stuff, but I have not used it,
myself=
.. I think you can find it referenced in another thread here on gluing
stuf=
f together.

Steve Leonard



All the Austrias I've seen/owned/flown including an SHK, used screws to attach the canopy to the tubular steel frame.
Good Luck,
Scott
The tubular steel frame
  #12  
Old August 19th 17, 02:59 PM posted to rec.aviation.soaring
firsys
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Posts: 36
Default What canopy adhesive to use?

On Monday, August 14, 2017 at 1:04:16 PM UTC-4, LongJourney wrote:
I've done a search in both RAS and on the web but I'm not finding the information I'm looking for. I'm restoring a 1963 S Austria and one of the previous owners used what I think is Sikaflex to bond the canopy glass to the metal canopy frame. It's now separating badly. What should I use to bond the plexiglass to the frame? And should I prime the metal frame and then scuff it where the glass will be bonded, or leave it bare until after the glass is glued on?

Thanks for your help,

Jeff


Do not use screws; they make for stress concentration and crack development..
I installed anew Kestrel 19 canopy using
RTV silcone preceeded by a primer; this gives a slightly flexible bond which alleviates stress concentration.


JMF

35 yrs later the Kestrel is still flying.
  #13  
Old August 20th 17, 05:05 AM posted to rec.aviation.soaring
Scott Williams
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Posts: 198
Default What canopy adhesive to use?

On Saturday, August 19, 2017 at 8:59:07 AM UTC-5, firsys wrote:
On Monday, August 14, 2017 at 1:04:16 PM UTC-4, LongJourney wrote:
I've done a search in both RAS and on the web but I'm not finding the information I'm looking for. I'm restoring a 1963 S Austria and one of the previous owners used what I think is Sikaflex to bond the canopy glass to the metal canopy frame. It's now separating badly. What should I use to bond the plexiglass to the frame? And should I prime the metal frame and then scuff it where the glass will be bonded, or leave it bare until after the glass is glued on?

Thanks for your help,

Jeff


Do not use screws; they make for stress concentration and crack development.

  #14  
Old August 20th 17, 10:18 AM posted to rec.aviation.soaring
Peter Whitehead
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Posts: 27
Default What canopy adhesive to use?

I have replaced a few Slingsby Skylark and Dart canopies.They also used countersunk flat headed screws, but into wooden frames. The trick is to drill the holes slightly oversize and bed the canopy onto a sealant which doesn't have huge and permanent bond strength. You just might want to use the frame again, as I did. Not metal tubular frame, but of similar vintage. Pete
  #15  
Old August 20th 17, 02:44 PM posted to rec.aviation.soaring
Scott Williams
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Posts: 198
Default What canopy adhesive to use?

On Sunday, August 20, 2017 at 4:18:33 AM UTC-5, Peter Whitehead wrote:
I have replaced a few Slingsby Skylark and Dart canopies.They also used countersunk flat headed screws, but into wooden frames. The trick is to drill the holes slightly oversize and bed the canopy onto a sealant which doesn't have huge and permanent bond strength. You just might want to use the frame again, as I did. Not metal tubular frame, but of similar vintage. Pete


Pete,
You are right, the Austria canopy frame is a welded up complicated item including locating pins and a plunger latch mechanism which is a Huge pain in the butt to fabricate!, The loss of which might prove itself close to impossible to replace.

Scott.
  #16  
Old August 21st 17, 02:20 PM posted to rec.aviation.soaring
LongJourney
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Posts: 33
Default What canopy adhesive to use?

On Sunday, August 20, 2017 at 4:18:33 AM UTC-5, Peter Whitehead wrote:
I have replaced a few Slingsby Skylark and Dart canopies.They also used countersunk flat headed screws, but into wooden frames. The trick is to drill the holes slightly oversize and bed the canopy onto a sealant which doesn't have huge and permanent bond strength. You just might want to use the frame again, as I did. Not metal tubular frame, but of similar vintage. Pete


Thanks, Scott. I have located said drawing and see that it was originally fastened with countersunk screws. I also heard from another Austria owner who told me that his canopy was fastened with screws. In addition, I scraped away some of the rubber black stuff on the frame and there are holes about every 4 inches. I have ordered screws and an acrylic drill bit from AS. I plan to drill the holes in the plexi a bit oversized to reduce stress and allow for expansion and contraction.

Thanks for all the help.
  #17  
Old August 21st 17, 04:06 PM posted to rec.aviation.soaring
[email protected]
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Posts: 2,124
Default What canopy adhesive to use?

On Monday, August 21, 2017 at 9:20:12 AM UTC-4, LongJourney wrote:
On Sunday, August 20, 2017 at 4:18:33 AM UTC-5, Peter Whitehead wrote:
I have replaced a few Slingsby Skylark and Dart canopies.They also used countersunk flat headed screws, but into wooden frames. The trick is to drill the holes slightly oversize and bed the canopy onto a sealant which doesn't have huge and permanent bond strength. You just might want to use the frame again, as I did. Not metal tubular frame, but of similar vintage. Pete


Thanks, Scott. I have located said drawing and see that it was originally fastened with countersunk screws. I also heard from another Austria owner who told me that his canopy was fastened with screws. In addition, I scraped away some of the rubber black stuff on the frame and there are holes about every 4 inches. I have ordered screws and an acrylic drill bit from AS. I plan to drill the holes in the plexi a bit oversized to reduce stress and allow for expansion and contraction.

Thanks for all the help.


I have installed about 20 canopies using screws. I NEVER drill holes. I create the holes using a rotary tool (Dremel) with a cone shaped diamond cutter about 1/8 inch in diameter. Gently pushing the spinning cutter does a combination of cut and melt that makes a good hole and does not create the issues that lead to cracking when a drill is used. After the primary is through, I walk in a circle to increase to final size. If flat head screws are used I make sure the primary hole is a little oversize so that when I countersink I don't get to a sharp edge on the far side. I countersink with a "normal" countersink that is sharp. I use low pressure and back up the plastic so I don't stress at the hole.
FWIW
Good Luck
UH
  #18  
Old August 22nd 17, 03:14 PM posted to rec.aviation.soaring
Peter Whitehead
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Posts: 27
Default What canopy adhesive to use?

I have been very careful and lucky with drilling holes, but yes, this way sounds good advice, I shall use my Dremel in future!Pete
  #19  
Old August 22nd 17, 03:54 PM posted to rec.aviation.soaring
Charlie M. (UH & 002 owner/pilot)
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Posts: 1,383
Default What canopy adhesive to use?

Key to drilling most plastic is to NOT use a new sharp bit. The cutting edge sharp corners leave grooves (stress risers) in the hole.
A "grinding bit", or burr "melts" its way through.
A dull twist drill may work.
A new bit where you drag a stone across the cutting edge (parallel with the bit long axis) to dull the edge (more of a round scraper than a bit that cuts) can help. Look at the "cutting edge" of a cheap masonary bit, same idea.
Back up your hole (small piece of soft wood works) to prevent "threading the bit through" when you get to the far side.
High speed and slow feed rate also help.

Practice on scrap plastic (you can buy small sheets of 1/8" acrylic at a hobby shop or Home Depot in the US). Cheaper than breaking an expensive canopy.
  #20  
Old August 22nd 17, 04:04 PM posted to rec.aviation.soaring
Craig Funston
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Posts: 208
Default What canopy adhesive to use?

Specialty bits for plexi are available.
http://www.eplastics.com/plexiglass_...tic_drill_bits

Craig
7Q
 




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