So I spent most of the day making some S-bend stays for Dan’s frame. And I learned several nice lessons:
-Making S-bends with enough tire clearance (in this case, we wanted 70mm minimum) for small 29er frames (this one has a 15″ seat tube) is a PAIN. In the end, the stays had to end up being only very subtle in their s-bendiness. I might need to make a tighter radius bending mandrel for this sort of situation – the 6″ radius wasn’t tight enough to allow both bends AND sufficient tire clearance. Maybe I’ll do a 5″ or 4.5″ radius mandrel sometime soon.
-Laying the stays on a flat surface (table) and letting the bent portion hang off is an easy way to assess if the bends are symmetrical. Of course, they’re never going to be *exactly* the same, but this method is good enough, as long as you’ve got a decent eye for detail. Thanks to years of messing with bikes, I do at this point.
-The bender itself needs some work. The mandrels are great (though Jason was right – they have started to warp slightly on the back side – though I don’t think this will end up being a problem) but the cradles/spine probably needs to be rebuilt/rethought. They tend to hang up, and the cradle holders are starting to bend from the force of bending the tubes. Not so good, especially if I want to bend beefier stays (these were just 16x.7mm cromoly ones, fairly strong, but nothing crazy). I need to make some cradles that are shorter (they hit the mandrel when trying to do tight bends) and possibly also that fit the radius of the tube better.
The frame is freakin’ sweet, though, especially now that it’s *finally* done.