An alternate way of installing roof rack bosses
December 17, 2016 at 7:52 pm #387EricParticipant
Since I have finish sanded but not yet varnished my shell, I plan on drilling for the roof bosses then, using waxed 1/4″ smooth rods as place holders, glue the uncoated bobosseto the roof with epoxy/cellofil. When the glue is mostly cured the rods will be removed (twisting them out with vise grips. Then I will glass them with 4 ounce glass ( a rectangle large enough to lap an inch or two onto the #2 panels). Then I will redrill and coat the holes. I’ll varnish them with the rest of the camper shell and finally install the Thule artificial rain gutters.
The above seems a lot easier than coating them twice with epoxy as a separate job, varnishing them as a separate job, and installing them to the roof at the same time as the rain gutters. Obviously they are permanent.December 18, 2016 at 3:02 am #388EricParticipant
Now that I’ve done it I have some important =modifications/corrections to my first post. I d<span style=”line-height: 1.5;”>idn’t glass the bosses; they are not large enough to round the corners enough to get the glass to conform. No biggy. The gutter covers/protects them well.</span>
I did not drill 1/4″ holes and use waxed rods as locator pins. Instead I used the gutter as a template and carefully marked the center of each bolt position on each <span style=”line-height: 1.5;”>boss with an awl. Then on a drill press I drilled 5/64″ holes at those locations. I then located the bosses over the paper template taped to the camper and drilled with the same bit now in my cordless drill (5/64″) though those holes, through the paper template, and through the camper roof (I first had to enlarge the boss footprint on the paper template). Remember, the holes are up, the gutter faces down. These holes are for small finish nails which I used as “locator pins” ( a boatbuilder trick that Russell Brown and I like and use a lot) to hold the bosses in exactly the intended position until the epoxy/cellofil cures. Its probably intentional but the mating surface of the bosses is cupped more than the curvature of the roof – so one needs to be sure there is enough glue in the center (fore and aft), or 4200 caulk if doing it the hymnal way. With the nails, no weights or clamping is needed. While I was at it I then slathered the first coat of epoxy over the bosses, finish nails and all. The nails will come out with visegrips tomorrow morning and the holes they leave will be enlarged to 1/4″ and coated twice with epoxy. All holes in okoume should receive two coats of epoxy.</span>
By the way, the warning in the hymnal about the bolt positions possibly being off , should be heeded! That’s why I used the paper template only for boss positioning not hole location – and was glad I did. Paper shrinks, printers vary in speed/accuracy – who knows.
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