ProjectVF - March 9th, 2008
I printed a photo of the
prototype and started making notes and establishing centerlines. After a few
days of thinking, I was able to see where changes were needed and how to
make sure it was done right. I dismantled the prototype and sketched out new
pieces to replace the original parts. These pieces have better geometry and tighter tolerances in the hopes of reducing slop & backlash.
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For the handlebar connection, I used a 1x2 screwed in place to hold a
bracket for the tie-rod. The tie-rod need to be positioned fairly accurately
and this does the trick. Unfortunately, the 1x2 had a weak spot which
cracked mere minutes after this photo was taken and prevented any downhill
tests. A replacement will be easy to make, but won't happen today.
Here's how the second version looks. Carriage bolts replaced the lag
screws used on the prototype, and the tie-rods were shortened. I painted the moving parts day-glo orange to make them easy to see during future downhill testing.
The only out-of-pocket expense was $2 for a few carriage bolts and nuts.
Everything else was recycled from the previous version or came from my scrap
pile.
Here's how it looks from the front. The linkage is fairly compact and
provides the 1:1 steering ratio I need. A steel version will be much
stronger, and should feel tighter, but that will have to wait for
further testing and analysis of this cheap experiment.
Here's a side view. The rear rocker arm and rear tie-rod still
need some adjustment, but overall this second version works much better than
the first. Test runs confirmed that tighter tolerances significantly reduced
backlash and slop, giving it a much safer feeling and improved feedback. I
plan on making a few more changes, gather some test data, and then start
looking at how to adapt it to ProjectVF.
