When I do this project I plan on using a glass suction cup or likely two from the inside and tie them off somewhere under load. In my opinion using these in tension while provide a much more even and stronger load across the portlights, keeping them in place while they cure. I prefer to keep my stantions for what they were intended, keeping the lifelines in place for an emergency.
This: http://m.grainger.com/mobile/product/FAST-CAP-Suction-Cup-Lifter-3KNF1 or similar product as was already mentioned. On Tue, Feb 17, 2015, 8:40 PM Dr. Mark Bodnar via CnC-List < cnc-list@cnc-list.com> wrote: > Robert, > Thanks for further input. My plan is to follow the same idea. I like your > keyhole idea to locate the window effectively. > One question - did you tape the window in place and then add the 795 into > the gap? Or did you put some 795 on the back of the acrylic (or the cabin > side)? I feel like I'd like to get more 795 in begins the acrylic - but > maybe the point is that the tape provides the holding power and the 795 is > just waterproofing sealant. > > Mark > > On February 17, 2015 2:22:57 PM AST, "Robert H. via CnC-List" < > cnc-list@cnc-list.com> wrote: > >> I am writing to update on my portlight replacement project. >> >> The installation went perfectly and the portlight looks great. >> >> Applying a few wood blocks to the inside of the portlight with removable, >> double-sided poster tape was a very effective way to affix the portlight in >> proper alignment. It slid into position like a puzzle piece, which is good >> because you only get one crack at it with the VHB tape. >> >> I also have a very good feeling about the VHB / DC 795 method - though >> time will be the ultimate judge. I am comforted by the thought that the >> tape and DC 795 will allow the portlight to expand and contract with heat >> and cold at a different rate that the cabin top without breaking the bond >> (in theory, anyway). >> >> For those that are thinking of using the same technique, here’s one final >> tip and a few comments. >> >> The tip: I had good success using a couple of telescoping hiking poles to >> apply pressure to the portlight by bracing them against the lifelines while >> the VHB tape set up. I also used a heat gun to warm up the cabin top before >> applying the portlight. >> >> I have no leaks in any of the other portlights (yet), so I’m going to >> wait until the weather warms up before I start on them. I learned that the >> initial bond of the VHB tape is dependent on both the application of >> continuous pressure and the ambient temperature. The 3M data sheet does a >> better job of explaining this than I will. Once you have a solid bond, >> it will hold well even in cold conditions, but you will be doing yourself a >> favour if you wait for warmer conditions. >> >> Sent from Windows Mail >> >> *From:* RPH via CnC-List <cnc-list@cnc-list.com> >> *Sent:* Sunday, February 15, 2015 9:06 AM >> *To:* cnc-list@cnc-list.com >> >> I have been reading the recent posts about windows and I thought that >> some might be interested to hear of my experience replacing the portlights >> on my 1989 30 MKII. Please note that I just started the on-boat part of the >> project yesterday and the work is not yet complete. >> >> In late fall I made tracings of the portlights which I transfered to 1/2 >> inch ply. The templates were cut using a circular saw with a guide rail >> system and a router. I then took my templates to a local plastics >> manufacturer, and they made the portlights from 1/4 inch plexiglass (Bronze >> 2404). The edges of the portlights are bevelled at 22.5 degrees (if I >> remember correctly). They turned out to be very good reproductions of the >> factory portlights. >> >> To ready myself for the project, I also purchased 36 yards of 3M VHB 4991 >> Tape 1/2" x 2.3mm, 4 tubes of Dow 795 structural adhesive (I chose white >> over black), and a can of DEI 010301 Black High-Temperature Silicone >> Coating exhaust paint. >> >> Yesterday, I attended at the boat with a view to replacing only the aft, >> starboard portlight (because I didn't want to bite off more than I could >> chew). I knew that the factory portlights were glued on with a methacrylate >> adhesive and that they would be difficult to remove. I brought my Dremel >> Multimax (which is like a Fein Multimaster) and tried using a flexible >> scraper to get between the plexi and the cabin top. This was not effective. >> In the end, I used several small putty knives which easily removed the >> portlight. >> >> What the putty knives did not remove was the remnants of the methacrylate >> adhesive. I tried several different techniques to remove the adhesive but >> ultimately decided that the better course would be to fair the area with 3m >> Premium Marine Filler. >> >> After sanding the fairing compound, I held the new portlight in place >> while my wife traced the window opening from inside the cabin onto the >> protective paper film. Then I used an Exacto knife to cut the paper along >> the tracing and removed the paper surrounding the window opening. Next, I >> spray painted the inside of the portlight black with the DEI paint so that >> the tape and Dow 795 will not be visible against the cabin top. >> >> I experimented with small pieces of the VHB tape and was surpised to see >> that it did not seem to stick too well to the cabin top even after the >> surface was carefully cleaned with alcohol. I decided that the fairing >> compound should be left to cure overnight and I will try again today. In >> any event, I have since read that the VHB tape needs time to reach maximum >> adhesion, and that it will adhere more quickly when the temperature is >> warmer. I'll bring a heat gun today to warm up the cabin top before >> applying the portlight. >> >> Anyway, if all goes well, the plan is to first affix the VHB tape to the >> inside of the portlight. Then, with the portlight dry-fitted in place, I >> will affix a few wooden blocks to the inside of the portlight (through the >> cabin top window opening) using double sided poster tape. My hope is that I >> can then remove the protective film from the other side of the VHB tape and >> then fit the portlight into place like a "key" into a keyhole. After the >> tape is set, I will then fill the gap around the outside with the Dow 795. >> >> That's the plan, anyway. >> >> Robert H. >> >> 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 >> >> > > > -- Dr. Mark Bodnar -- > Bedford Chiropractic > _______________________________________________ > > 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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