I couldn't bring myself to spend $150+ for the rotopax roof mount plate ($60) and a pair of handles ($45 each), not to mention the extra HW required to actually mount the whole thing to my roof. So I bought a 2" wide, 1/8" thick aluminum bar stock from Home Despot for $10 (in hindsight I'd go back and use 1.5" side, 1/8" thick steel as the aluminum flexes a bit when cranking down the U bolts) , two round steel outdoor electric outlet covers for a few bucks , and two stainless steel 3/8" ID washers (for the 3" bolts below). The rest came from McMaster-Carr. Total cost about $50 in parts, plus some drilling and cutting effort.
The final product installed. I used to use 4 or 5 kayak lashing straps, which work ok but take 5-10 minutes to get on and off securely in order to vent the can. For the time being I kept one strap on just for safety until I've put some miles on the setup and I'm sure it won't work its way loose. (I did not use locktite on the U bolts because I'm not sure I want to always keep this installed (or at least installed in the same spot) since as-mounted I think my kayaks won't fit).
The T-handle nut is recessed in the bottom part of the handle, and so it fits down into plate. Thus the load from the can is distributed across the round plate, and the plate is secured by the entire T handle (not just the round base).
This is how the ABS block and bolt fit with the top plate and T handle removed. The plate has 3 holes drilled in it - one in the center which is 3/4" and large enough for the handle to drop down, and then holes on either side to ensure the plate sits flush. I know the real Rotopax handle has recessed bumps to hold the handle in place, but I'm using vibration resistant handles which have a locknut in them so I'm not worried about it working loose.
Top view of the mount. I cut the ABS bar stock down and used a grinding wheel on my drill to round off the ends so it fits nicely inside the Rotopax mounting holes. The top mount plates are kinda hacked since the ones from HD are about 1/4 to 1/3" too wide. I couldn't source the right side plates this week so I just cut them with a pair of tin snips and sanded down the edges for now. I'll find correctly-sized plates in the future and re-drill/re-paint.
ABS block (test fitting). There's a washer and I used the coupling nut though a regular nut probably would worked just as well and required less effort in hind sight.
I had to shorten the U bolts to fit. The binding barrels ensure there's minimal additional height since the Rotopax sits on the bar stock (and thus rests on the bolt heads). Since the bar stock plus screw heads are about 1/4" taller than the rack I wrapped some foam in 3M Super-88 tape about 3"-4" over on either side of the bar stock (you can kinda see it 2 photos up) so that the can has something to rest on.
McMaster-Carr parts list for those interested.
The final product installed. I used to use 4 or 5 kayak lashing straps, which work ok but take 5-10 minutes to get on and off securely in order to vent the can. For the time being I kept one strap on just for safety until I've put some miles on the setup and I'm sure it won't work its way loose. (I did not use locktite on the U bolts because I'm not sure I want to always keep this installed (or at least installed in the same spot) since as-mounted I think my kayaks won't fit).
The T-handle nut is recessed in the bottom part of the handle, and so it fits down into plate. Thus the load from the can is distributed across the round plate, and the plate is secured by the entire T handle (not just the round base).
This is how the ABS block and bolt fit with the top plate and T handle removed. The plate has 3 holes drilled in it - one in the center which is 3/4" and large enough for the handle to drop down, and then holes on either side to ensure the plate sits flush. I know the real Rotopax handle has recessed bumps to hold the handle in place, but I'm using vibration resistant handles which have a locknut in them so I'm not worried about it working loose.
Top view of the mount. I cut the ABS bar stock down and used a grinding wheel on my drill to round off the ends so it fits nicely inside the Rotopax mounting holes. The top mount plates are kinda hacked since the ones from HD are about 1/4 to 1/3" too wide. I couldn't source the right side plates this week so I just cut them with a pair of tin snips and sanded down the edges for now. I'll find correctly-sized plates in the future and re-drill/re-paint.
ABS block (test fitting). There's a washer and I used the coupling nut though a regular nut probably would worked just as well and required less effort in hind sight.
I had to shorten the U bolts to fit. The binding barrels ensure there's minimal additional height since the Rotopax sits on the bar stock (and thus rests on the bolt heads). Since the bar stock plus screw heads are about 1/4" taller than the rack I wrapped some foam in 3M Super-88 tape about 3"-4" over on either side of the bar stock (you can kinda see it 2 photos up) so that the can has something to rest on.
McMaster-Carr parts list for those interested.
My use case is for four rototrax, which I'm looking at making dedicated roof mounts for. They stack up to an odd height in 4x (2x fits fine on 2 gal ext, 4x not so much - nice product design there for a completely block based system, Rotopax, but I digress). Rotopax provided me some spacers gratis when I asked, but if I'm going to use spacers, I might as well just custom the mount height and have dedicated mounts. the real blocker was coming to terms with buying two more mounts (roof mounts for trax, bumper mounts for pax). I just didn't have a good plan for the 'block' until your post!
