Message: 12 List-Post: krnet@list.krnet.org Date: Wed, 22 Dec 2010 10:51:18 -0800 (PST) From: oceanmanus <oceanma...@yahoo.com> Subject: Re: KR> Canopy Gluing- Epoxy
Do sand the surface edges well with very coarse sand paper, both sides. At Lancair we used to install plexiglass windows in pressurized planes using the method described below. One of them broke at altitude once and de pressurized the cabin suddenly but it wasn't due to a glue joint failure. Any holes drilled around the edges make for a potential stress riser. Drill no holes. Be sure to mask off the canopy with electrical tape then masking tape on top of that. Don't let anything except the electrical tape touch the plexiglass, it' very hard to clean the tape glue especially if it's duct tape. Kerosene or cleaning solvent (paint thinner) with a soft cotton cloth works well to clean plexiglass. Joe Beyer Scappoose, Ore. ________________________________ From: Mark Langford <m...@n56ml.com> To: KRnet <kr...@mylist.net> Sent: Wed, December 22, 2010 11:47:58 AM Subject: Re: KR> Canopy Gluing- Epoxy Steve Phillabaum wrote: >>I have a Todd's KR canopy and I sanded in a good scratch finish in the >>area of the epoxy and then sandwiched in the conopy between glass on both >>sides uning areopoxy. I don't think I could get it appart without some >>damage. Let us know what he has to say.<< That'll work fine. I would think most epoxies would stick just fine to acrylic after it's been roughed up with rough sandpaper to give it some "teeth". I think this is even detailed in the Bengelis books. I suspect those having problems didn't do the roughing part. I wondered about the quality of that bond when I did mine the same way (overlapping the acrylic by about 1.5"-2" all the way around, but there is zero sign of delaminiation anywhere. T-88 may not be the best choice because it's not very viscous and may not soak into as many of the scratches, but I'd bet it's still a pretty good bonding agent for glass. I used Aeropoxy, and can tell you that it works for sure, at least up to 240 mph. Another key is HOW you do it...you need to sandwich the acrylic on both sides with glass to put it in a sort of "double shear" rather than glass on only one side, eliminating a "tension only" kind of failure where the fiberglass can just peel away from the acrylic due to some wierd loading condition. I think that's just good common sense though... Mark Langford m...@n56ml.com website www.n56ml.com _______________________________________ **
