Someone PMed some questions to me about my hatch doors project. I thought I'd answer them here where everyone can find my answers.
<span style="font-size:10pt;line-height:100%">What is the "5-minute epoxy" you used for the "L" pieces, and where did you buy it?</span><span style="font-size:10pt;line-height:100%"> Where did you buy Reflectix, . . . and 3M Marine Adhesive Sealant Fast Cure 4200?</span>
The 5-minute epoxy is the standard stuff you buy from any hardware store. Reflectix insulation is available in the heating/cooling section of many hardware stores. (Mine came from Lowes.)
The marine adhesive should be available from most boating/marine stores; look for a product that says it will work on fiberglass and plastic (I had to return the original product I bought and switch it to the Fast Cure 4200 for this reason), and remember to remove the wax coat from the area where the hatch frames will be (MEK solvent works well . . . wear gloves) then sand lightly. Remove excess sealant before it hardens.
<span style="font-family:Verdana">Where did you buy . . . </span><span style="font-size:10pt;line-height:100%">N50 neodymium magnets . . . ? </span>
Neodymium magnets can be had from a number of places online. eBay usually has pages and pages of them. Just use "neodymium" as a search term and look for magnets rated "N40" and above. (Magnets with higher numbers are stronger, and you need two very strong magnets to hold the door up through the trailer's fiberglass wall. I bought most of my magnets from K & J Magnetics, which is an eBay seller that also has a non-eBay web store
. My posts have details on the two types of magnets I used, a smaller one on the door and a larger one inside the trailer. Be sure to get the magnets lined up and the right way around or they will push away from each other rather than pulling together!
I would like to add two warnings about these very strong magnets. The first is that they are just that: very strong. They are lots of fun to play with, but you really can pinch a finger with the larger magnets I used in my project. Perhaps more importantly, however, is if you let them come together without the little isolator ring in place between them one of two things will happen: either you will have a fun time getting them apart or they will come together with so much force that one or both will shatter into small, sharp pieces of somewhat toxic metals, so it's a good idea to wear safety glasses when you're working with the stronger magnets. If a magnet does shatter use another magnet inside a paper bag to attract all the sharp little bits of magnet, then pry the little bits off and throw them away, take the paper bag off the collecting magnet by turning it inside out and throw the bag away, too.
I should also mention that people who have pacemakers can be adversely affected by strong magnets. When I measured the strength of these magnets I found the strength of the stronger N50 magnet I used fell to the background level of the earth's magnetic field at just over ten inches (10-3/8", the smaller magnet at 8-3/4"). Since the magnet is installed well below shoulder level (where pacemakers are installed) and is isolated from any pacemaker by at least 4" of foam and the thickness of a pacemaker user's body I don't think it's at all likely that someone with a pacemaker sitting in the dinette would get their pacemaker within 10" of the magnet. Nevertheless pacemaker users might want to keep that in mind before you put this modification in the backrest of your trailer. One alternative would be to replace the magnet embedded in the trailer wall of the dinette with a 2" square by 1/4" thick piece of pot metal iron and replace the smaller magnet on the hatch door with a stronger magnet.
K&J Magnetics has a safety sheet
discussing these stronger magnets. It's short and worth reading.
<span style="font-size:10pt;line-height:100%">Also, because my hatch is a 13" X 17", and not involved with the benches like yours were, I'm thinking I can get by with just four sticks for the frame - maybe mitred, maybe not. Any thoughts on that?</span>
I made "L" shaped brace to prevent "concentration" of stress as the trailer wall flexes at the corners of the cut fiberglass, where they could cause cracking.
The best way I could come up with to distribute those forces was to make the "L" shaped braces. It wasn't too hard: I used a door lockset hole cutter to radius the inside corner and a power saw to cut up to the hole, then a hand saw to finish the cut to get the inner side of each brace, and a power sander to round off the outer corners of the "L" braces.