Originally Posted by Tiggy
I visited rowframes site. Arent those speedrails installed on the frames? They gotta be worth something?
Having used 'em for years, on several frames, I prefer them to the Lowe-Pro joints. Only one failure: a joint on an ultralight playcat frame loosened up and came apart (just as I hit a big hole). My fault. I built the frame with only one front crossmember— the footbar— and there was too much flex. I knew in advance there might be. Ooops! I pinned the joints, but there was still too much stress. So—
A solution is to 'box' your frame in every direction there might be twist. Given the ends and crossmembers, most raft frames are boxed horizontally, but not vertically, so they tend to twist and flex and loosen up. A cat frame is under more stress and should be boxed in a vertical way at both ends, with at least two crossmembers.
Two other tips for SpeedRail joints. First, I use 2-inch hardwood dowel plugs at the ends of every pipe that goes into a joint— hard to find dowels for the larger pipe sizes. But that helps prevent deformation of the pipe.
Second, you can put in a divot for the setscrew to prevent rotation— insert the pipe, tighten the setscrew just enough to mark it, then use a large drill bit or countersink (2-3 mm— not too deep). Put the pipe in again, carefully locate the divot with the setscrew, and make some sort of marks so you can line it up again. With 90° elbow joints, one piece of pipe can go farther into the joint than the other— whichever pipe is more prone to flexing or twisting should be deepest in the joint. Mark not only the line of rotation (on both pipe and joint), but the depth in the joint (on the pipe)– I use Sharpies when I'm setting up a frame. Once you get it wired, you can scratch or file a mark.
For breakdown frames, I also die-stamp the location on the pipe, e.g.
LFO (left front outboard) so I can put it together without too much fuss. Marking the pipes can also be a good tactic with a pro-built breakdown frame— especially if you'll have 'help' putting it together at the launch site.