S-bend seat stays

This was my first attempt at S-bends seatstays. I have built two frames with single-bend stays but those were a couple years ago and I did the single bend on my 7″ radius oak fork blade bender.  After hummin and hawing for awhile and attempting to make my own somewhat clunky 8″ radius bender out of MDF,  I decided to fork over the Franklin’s and get a properly made tool that will last for a long time and make life easier.  There are many bender options – from expensive used DiAcro’s that need customization, to new benders from ProTools and the like – but most of them need some customization to get the job done right (to fully encapsulate and support the tube so it doesn’t fold or flatten).  After looking at simplicity, cost, amount of work needed to do what I want, the Anvil was the obvious choice for me.  So for many frames to come I’ll be using my new Mr. Bender Rodriguez.  I got the 3/4″x 9.375″ mandrel for doing anything from 5/8″ stays to fork blades (yet to attempt that).  With it I can get away from mostly doing my time-intensive segmented wishbone stays to quickly bending single or S-bends in two tubing diameters (5/8″, 3/4″).  After practicing on some 4130 x 0.035″ and 0.028″ tubes, i went for it with some Nova single taper stays.  There was a little bit of flattening on the bend (5/8″ tube, 3/4″ mandrel) but almost nothing to write about.  After getting the initial bend, you flip the tube for the 2nd bend and use the phase keeper arm to make sure the bend is in the same plane as the 1st.  Then when it seemed like it’d work (comparing it to the life-sized drawing), I measured down from the tire mark on the stay/apex of the 1st curve (widest part of tire), and marked where the top of the slot needed to end up.  Then, i cut and slotted the stay for the dropout in the mill.

For now my ‘custom’ seatstay mitering fixture will work.  It’s not super pretty but i also didn’t have to file to fit at all after getting the right miter length.  The aluminum extrusion doesn’t clamp that well in the mill vise, but it’s mostly because i’m clamping so little of it due to the angle of the miter.  It all stays put after some serious force but I’m thinking that I need to fabricate an updated mount. But for now this will be my only non-Anvil fixture 🙂

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