rec.sport.unicycling · Public discussion

Re: uni frame...

Started by gerblefranklin · · Last activity · 1 post · 260 views

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rec.sport.unicycling
Published
7 October 2005
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gerblefranklin
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  1. What tools do you have? What materials do you want to use? How much
    experience do you have using these tools on said materials? I have
    complete drawings for a titanium hunter-esque frame somewhere on my
    shelves, but how many people on this forum can skillfully bend, weld,
    and machine titanium? I know I'm not one of them. "Sumthing I can make"
    is an awfulyl open statement. Making something even as simple as a
    unicycle frame can be quite a project.

    I'm building another machined aluminum trials frame for the heck of it
    (well, to justify not buying a second milling machine, long story), and
    if you want I can send you some drawings. Still, though, you need
    access to and expertise on a milling machine and preferrably a lathe as
    well. This isn't the ideal beginner project, being as the
    seattube-crown interface is a 0.002" interference fit. You ideally
    would need tolerances of +/- 0.0005" for that, and aligning and setting
    up the cuts for the bearings ain't easy either.

    The material is 6061-T651 aluminum. You need a piece of plate about
    24"x1/2"x4" for the legs, a chunk 2"x5"x4" for the crown, and a tube
    1.5"ODx1.25"IDx~8-10" long for the seattube. You would need at minimum
    a milling machine that accepts tooling at least with 1/2" shanks. It
    must have at the very least 13" of travel on the x axis, 6" on the y,
    and 4" in Z. Some of the cuts are very rough ont he machine, and even
    machines as rigid as a bridgeport can show measurable flex.

    For a lathe you need one that swings at least 6", prefferably 10 or 12.
    A vertical metalcutting bandsaw is *extremely* helpful.

    For a beginner this project could take as long as 6 months, however if
    you already have machining experience, you could probably do it in
    about a week or so. Working intermittently after school between hw,
    I've done about 75% of the forklegs in about a week. All that's left is
    to cut the bearing slots and locate and drill the bolt holes to attach
    to the crown.

    My first version of this frame was adaquately strong, however it may
    not be for those who do 6' drops without refined technique. I've abused
    it for about 4 months without any failures, though, so it must be
    decent.

    Do a search, i've posted about frame design and construction many, many
    times (too many...). Others on this forum know more than me, but post
    less. If you can find posts by Showard or cyberbellum, they know a ton
    about designing these things, and can tell you more than me.

    Ugh, long post, i hope it helps, assuming you read it...

    Edit: If you want to weld the frame, well, taht's another story.
    Assuming you're already a skilled TIG welder and have the proper
    equipment, you could probably build a nice chromoly KH knockoff frame
    ina bout 2 days, assuming you used uni.com bearing holders. If you're
    not a skilled welder, you still could probably do a decent stainless
    steel KH knockoff frame in about a week, assuming you already have
    bearing holders.

    --
    gerblefranklin

    http://gallery.unicyclist.com/Trials-Muni

    Nick's main man.

    "I love freedom dearly, ideally, in theory, but in reality we're not
    there yet--Not nearly."--Cold Duck Complex
    ------------------------------------------------------------------------
    gerblefranklin's Profile: http://www.unicyclist.com/profile/4295
    View this thread: http://www.unicyclist.com/thread/43795

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