Friday, January 22, 2016

Cruiser Bars, Riser Bars, and Compound Bends

I've been mulling this one over for a while now.  Several years.  I've made various efforts towards compound bends with chainstays over the past couple years, mostly rotating by eye or with an angle finder and producing a fair bit of scrap metal in the effort.  Handlebars really put your bending skills to the test.  And the came to step up and pass the test.  Commercial handlebar offerings don't meet the needs of the next two works in progress, and the one guy that makes such an appropriate product I guess isn't much for email.  So my hand was forced,  Lemmy died, and I'm throwing All the Aces.  I'm taking cruiser bars and riser bars on at the custom level.  Custom rise, custom sweep, custom width, custom comfort, 7/8" clamp cause its the BMX standard, unchanged.

Of course tooling updates were in order.  But I wanted to try things out a bit first before fully committing to a new bender.  I have a design fairly worked out in my head, but that's still a far cry from having a working unit in hand, so I figured the prudent thing to do here for time sake was update the ol' Handy 7/8" bender once again.  The ol' Handy has been $100 well spent.  It came from ebay in 2010 and since this picutre has been through several updates to improve its performance.  Its design flaws show a bit in thin wall tubing, but it has facilitated nearly all my learning of bending mechanics.  It is shown below with the first clamp mod.  For this project the clamp was scrapped in favor of a new one...imagine!

With the new parts in hand several bars were drawn out, raw lengths calculated, and the bends made sequentially.  As for the rest of the details, well, I've got to leave you something to think about.  I will say that by far the hardest problem that I'm still trying to wrap my head around is the vector math involved in creating a three dimensional part.  I got stumped several times on paper before taking the try and see approach to prototyping.  I'll continue to pursue the magic formula, but for now the bars are straight (left and right grip area are parallel on the surface plate, and the clamp surface is flat when the ends are touching), and the bends are even and symmetrical.  This hand felt like a big win, but the game rolls on.

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