A different approach to building a double rail frame. - Mountain Buzz

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Old 07-22-2009   #1
Groveland, California
Join Date: Nov 2008
Posts: 229
A different approach to building a double rail frame.

OK, I have just about wrapped up my frame building project, so I thought it would be a good time to share some ideas and pics.

I started out with the idea of bending up a tubular frame, welding in some aluminum diamond plate for the side decking, and welding spuds to the side pieces that I could snap-pin the cross bars to for a break down frame. Some wise people on the Buzz suggested that it would be a good idea to make the frame adjustable, and to not weld it together.

I took their advice, went back to the drawing board, and designed a fitting that would be adjustable, support double side rails, have a means to support/fasten the side decking, and quickly disconnect from the crossbars with snap pins, while keeping the side assemblies (fittings, double rails and decking) together as a unit.

After many hours on my CAD, and a few different versions, I came up with something I liked. I purchased some stock, fabricated some tooling, and machined the fittings. Here is what I came up with:

Fittings on the double rails:

Frame Assembled:

With side decking (I'm still waiting for the stainless fasteners to hold the decking down):

The cross bars can be used as double side rails for a day frame setup. (I have a drop bag that fits the front bay, and will make a plywood or HDPE cover for it.):

Someday, if I buy another raft that has different tube spacing, all I will need to do to make this frame work is to fabricate another set of crossbars. And if for some reason I want to completely change the layout, it can be done easily.

It has been a fun project, and I am very happy with how it turned out.

Thanks for looking!

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Old 07-22-2009   #2
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I think I may be speaking for many people here... These are SUPER SWEET.

How much do you want for each of the fittings?

as an aside: What tube diameter is your boat? Will these fittings work on a range of tube sizes, or only on your size tube?
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Old 07-22-2009   #3
Rafter Town, California
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Guy that is brilliant! You ought to think about selling a few of those!
I might want a few!
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Old 07-22-2009   #4
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Christopher Creek, Arizona
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NICE. Your work is professional and a pleasure to ponder over. Thanks for sharing. I have a couple thoughts about the setup. Please do not take them for anything other than constructive because that is how they are offered. I am thinking those tubes need chafe protection, those snap pins might be a pain catching on things when you really do not need the extra drama; in a flip situation for example. I really like your choice of the NRS towers due their ability to take severe hits without bending or breaking something but I am wondering about the oar length/angle/stroke geometry with the locks set out off tube center. Those fitting pics are calendar material for raftheads.
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Old 07-22-2009   #5
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C. Springs, Colorado
Join Date: Aug 2004
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WOW!! Impressive....... the only thing I would add is remote control hydraulics to raise and lower your dry box lids

Seriously....you could market those fitting......and if you do.....I want some.
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Old 07-22-2009   #6
Dave Frank's Avatar
Boulder, Colorado
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Boy I wish I had access to a machine shop,(and the skills to use it).

I bet those fittings retail for $119.99 each!

Do you have any bright ideas to hold down your dry boxes? I'd like to get away from camming mine down and having to undo 2 straps and the latches to open them.

Seems with the two on the side, you might have some clever scheme going.

Recretec's butterfly latch hold downs look nice, but harder to implement on round tubing...

(seven two 0)-298-2242
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Old 07-22-2009   #7
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Durango, Colorado
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I know it's wrong to get all enthused by frame porn, but I can't help it. Gorgeous fittings!
You can never step into the same river; for new waters are always flowing on to you. - Heraclitus of Ephesus
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Old 07-22-2009   #8
timbuktu, Colorado
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She thinks my frame is sexy!
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Old 07-22-2009   #9
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Castle Rock, Colorado
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Those connectors look sweet! Nice job
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Old 07-22-2009   #10
the grove, Oregon
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I just did a few calculations, and to be at all competative the fittings need to be less than about $40 each retail to be somewhat competative with the other higher end componenent frames (although these fittings are the top standard right now!). I am thinking a patent is warranted.

8 fittings at $40 = $320
45 feet of pipe ($4/ft) = $180
2 lopros (or your single fittings) $36
foot bar? = $100
8" oar towers = $89

Total = $725 (about the same as if using low pros for a double rail, but the HPMG ones are light years better)

Yeah you could use speed rails for a lot cheaper, but these are so sweet and the tapped screw holes for side decking make it the bomb.

You don't need no chafe strip, all of the speed rail fitting frames use the keeper pins, I have them and they don't cause any problem. Besides with the aire trib (I think that is what you have there) the "outer skin" is the chafe strip, it isn't the air holding layer.

These should easily work with larger tubes. As you can see from the photo, the radius is not such that it lays on the tubes, only the rails are touching. As the tubes increase in diameter, the curvature will be even flatter compared to the fittings, and the double side rails will still be the only point of contact.
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