Well, the roll bar is in and braced, though I'm not as happy with my fabrication as I could be...
I got the bracing in over the course two days and it all started out pretty kewl. The 2 rearward braces mate with the 1.5 OD roll bar at the top, and the .78 shock/fender bracket mounts at the bottom. I figured fish-mouthing the tubes on my drill press would be a good method, and so it turned out.
cutting the big end...
looks pretty good!
after a little cleanup, a perfect fit.
since I had the big end cut set up, I did the second tube right away with similar results. then I moved on to the small end. the stock Intruder 1400 fender bracket mount has a 20mm (.781 ) OD, so I figured I'd just cut it out with a .75 hole saw and then massage the fit with a half round file.
boring the .75 hole at the proper length.
once I got the hole bored, I cut the end of the tube off halfway thru the hole to make the fishmouth...minor massaging and cleanup gave a good fit.
after that it was a simple-ish matter to get both tubes to fit in place pretty well. welding magnets, a piece of scrap angle, and two C-clamps completed the setup, and I called it quits for that evening.
Now, the .095 and .125 wall thicknesses of the tube were under the max material thickness my 135 amp MID unit is capable of, and over the last couple years of the build I've gotten pretty adept at welding from below, so I thought the weld would go alot more smoothly than it did.
suffice to say, I was somewhat dissapointed by the results, and had to resort to the trick of heating the tubes to orange hot with my gas torches, and then laying on a bead, which gave a good melt under the arc. I made several passes this way, and then worked the resulting welds over with the radius-edge flap disc...but, eh. even cleaned up, these arent' nearly as pleasing to the eye as the join at the bottom of the roll bar main tube. Even though I've successfully joined materials of these thicknesses before, I think the DOM tubing acts as a greater heatsink than plate or sq tube and thus the welds remain cold with poor penetration.
roll bar braces installed.
ground and smoothed upper weld detail.
and, in the interest of full disclosure, the ugly, hideous, bottom blobfest.
not a pretty sight, right?
the lesson here, is, for tubes at this thickness, a more powerful welder is a better method. Of course, that would have meant trucking the frame to my buddy's automotive shop to use his 180 amp welder, and would have added another level of significant hassle to the build. The trick of heating the tubes orange-hot worked pretty well, and I'd likely have gotten better results initially if I'd done that right from the beginning, as opposed to after I'd already laid down a kinda shitty bead.
I have a couple choices here, 1. cut the braces out, grind away the weld remnants and do it over, 2. leave it alone and don't worry about it, since, as this will primarily be a street vehicle the roll bar will mostly be used as a convenient handhold for pushing the thing out of parking spaces, or 3. add some gusseting in the corners and then see number 2.
I'm leaning towards 3, right now.
throughout this build, welding skills have come thru often hard lessons, like this one.
on the upside, it fits around the gas tank just like I planned. There's a good .25 inch clearance between the rear braces and the tank.
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