Also, a little heat using a heat gun (or the sun in the tropics) will make it easier to separate.
Bob Sent from my iPhone, Bob Boyer > On Dec 3, 2015, at 12:49 PM, Gary Russell via CnC-List > <cnc-list@cnc-list.com> wrote: > > Hi Pete, > Although you can't pull the VHB apart with your fingers, it would be > very easy (I think) to separate with a blade. Although I haven't tried it, > the tape is quite thick (0.090") and made of a firm acrylic foam, so cutting > the bond should do the trick. A sharp razor blade should be able to remove > the residue. > > Gary > S/V High Maintenance > '90 C&C 37 Plus > East Greenwich, RI, USA > > ~~~~~~~_/)~~~~~~ > > >> On Thu, Dec 3, 2015 at 9:17 AM, Pete Shelquist via CnC-List >> <cnc-list@cnc-list.com> wrote: >> Just an observation; The VHB tape seems like a more simple installation. >> However, I’m curious if Plexus is evil because it’s too hard and tenacious, >> yet the VHB joined parts won’t come apart, in 5-10 yrs when redoing windows >> again it sounds like we’ll be calling VHB evil. >> >> >> >> I don’t have a better solution, and question if there’s really a good one >> out there. It sounds like we need to keep templates of the lenses and deal >> with cutting and filling around the frame when the connection fails. >> >> >> >> >> >> >> >> From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Gary >> Russell via CnC-List >> Sent: Wednesday, December 02, 2015 7:47 PM >> To: C&C List >> Cc: Gary Russell >> Subject: Stus-List Bonded Windows (continued) >> >> >> >> For those who were following my post on bonded windows on High Maintenance, >> I have an update and many thoughts on the project enumerated below. I have >> successfully installed two windows on the starboard side and replaced the >> acrylic on all the hatches and can say that the project has been very >> successful. I have terminated my project at this point as the temperatures >> are now too low for the VHB tape which requires a temperature of greater >> than 60 degrees F for application. Here are my observations: >> >> >> >> #1. Plexus is evil stuff and should not be allowed on a boat. It is too >> hard and tenacious a bond. Because fiberglass and acrylic have such a >> different expansion coefficient, fracture of the acrylic is assured. >> Removing the stuff is impossible without destroying the gel coat underneath. >> I tried a sharp blade between the fiberglass and the acrylic and all I >> managed to do was rip up the gel coat. >> >> >> >> #2. Before removing the windows, make a template out of some thin plywood >> (or other material) because the window will (no doubt) come out in pieces >> and you will have nothing as a reference for making the new windows. >> >> >> >> #3. I finally was successful removing the acrylic with a 5/8” router bit >> set to a depth equal to the thickness of the acrylic plus the thickness of >> the Plexus. I actually used a Roto-Zip instead of a router as it had a >> smaller footprint and was easier to handle. I free-handed the router to cut >> through the acrylic and into the Plexus. It’s risky but effective. Don’t >> cut all the way around the perimeter, but leave tabs to support the window. >> Otherwise, the window will sink under the weight of the router and you will >> cut into the gel coat. You can break out the tabs later. >> >> >> >> #4. Once the windows were out, I used West System epoxy thickened with low >> density filler to repair any damage to the gel coat. Fortunately, all my >> gel coat damage was limited to the area under the windows. Once the windows >> are out and the damage is repaired, the rest is fun and easy. >> >> >> >> #5. I cut the new window out of 3/8” Plexiglas using a pattern router bit >> (sometimes called a Formica trimmer). I used masking tape folded in half >> lengthwise to stick the new Plexiglas to the old window (or template). I >> ran the tape at right angles to insure that they wouldn’t slide in either >> direction with respect to each other. It does a very nice job and is quite >> easy. I then used a 1/8” round off router bit on the outside edge of the >> new window for cosmetic reasons and a 45 degree chamfer bit on the inside >> edge to make room for the Dow Corning 795 silicone. >> >> >> >> #6. I installed the 3M VHB 4991 tape on the coach roof and masked around >> where I wanted the window to go. This would help me locate the window and >> provide the masking for the Dow Corning 795 silicone to follow. I also >> masked the edge of the new window for the same reason. >> >> >> >> #7. Now cones the tricky part. You only get one shot with the VHB tape, >> because once it is down, it is not coming up. I tried adhering two small >> pieces of acrylic to each other with about two square inches of VHB tape, >> and I can assure you, you won’t pull them apart. VHB is amazing stuff. As >> a guide, I mounted two small wooden blocks to the masking take below the >> window with a small piece of VHB tape. By attaching it to the masking tape, >> I was sure I could get it back off. Actually, VHB doesn’t stick very well >> to masking tape anyway. I also stuck a small wooden block to the masking >> tape at one end of the window as well. This allowed me to set the window on >> the two bottom block and then slide it over to the end block before pushing >> the window into place. By all means, make several trial runs with the film >> still on the VHB tape before removing the film. Once the film is off you >> are committed. I pushed the window in place and it looked perfect. Then it >> is simply a matter of squirting the Dow Corning stuff into the gap and >> smoothing it out with a finger. As soon as the silicon is smoothed out, you >> can remove the masking tape and pour yourself a stiff one, while you admire >> the fine job you have done. >> >> >> >> #8. There was concern expressed that the VHB tape would be visible through >> the window, and it was suggested that the window should be painted with >> Krylon Fusion Black. Actually, the VHB tape is the same color as the Plexus >> which is not visible, so the VHB won’t be visible either. No paint is >> necessary. I used the darker shade of grey Plexiglas and can say that it >> look spectacular. The darker shade really “pops” and the contrast is >> particularly attractive (in my humble opinion). The darker color makes it >> difficult to see into the boat, but has a minimal effect when looking out. >> The VHB is not visible at all. >> >> >> >> #9. There was also concern expressed concerning whether the curvature of >> the coach roof would cause a flexing force to peel the VHB tape. I can say >> that the radius of curvature is very large (>20 feet) and the forces are >> thus very small. 3/8” acrylic over those lengths is quite flexible. I see >> no problem at all. >> >> >> >> #9. I have posted some pictures on Google Drive and I think you can view >> them at: >> >> >> >> https://drive.google.com/folderview?id=0BwQRSP2fYIFmemxYOGlVcHNUNVk&usp=sharing >> >> >> >> I am new to posting pictures, so if you have trouble seeing them, email me >> and we can get it fixed. I will add more pictures as they become available. >> >> >> >> #10. Needless to say, I am thrilled with the outcome so far. I have also >> re-glazed the hatches using the Boatworks video and they came out >> spectacular as well. The only difference I made from their recommendations >> is that I bedded the acrylic in butyl tape instead of the Dow Corning 795 >> because it was much easier to get a uniform bead and that was the way it was >> done from the factory. I still filled the gap around the windows with the >> Dow Corning 795. Boatworks is right, the Dow Corning 795 is nice stuff. >> >> >> >> #11. If I have left anything out or you have any questions about this post, >> just give me a shout. >> >> >> >> Gary >> >> S/V High Maintenance >> >> ’90 C&C 37 Plus >> >> East Greenwich, RI, USA >> >> ~~~~~~~_/)~~~~~~ >> >> >> _______________________________________________ >> >> Email address: >> CnC-List@cnc-list.com >> To change your list preferences, including unsubscribing -- go to the bottom >> of page at: >> http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com >> >> > > _______________________________________________ > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go to the bottom > of page at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com >
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