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Author Topic: Doing something funky in the (machine & welding) shop  (Read 1512 times)

sebwiers




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Doing something funky in the (machine & welding) shop
« on: November 29, 2015, 07:20:16 PM »

    St.Paul.Slim


      "The Ayatollah of Rocknrolla"

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    Re: Doing something funky in the (machine & welding) shop
    « Reply #1 on: November 30, 2015, 06:49:52 AM »
  • Cool.  What's going to make it go fast?

    vince




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #2 on: November 30, 2015, 08:13:56 AM »
  • To much time on your hands with nothing to do. Looks like a nice First Thursday bike.
    2015 YZFR1 Yamaha Raven
    2012 ZX10R ABS Ninja Kawasaki
    2005 Mach Z 1000
    Black flag me if you want, catch me if you can.
    I bought it to ride. Not to look at.

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #3 on: November 30, 2015, 08:37:09 AM »
  • Cool.  What's going to make it go fast?

    Is an XJ750, motor is stock.  Ran when I pulled it out, just needs a couple valve shims replaced.  The stock exhaust and intake won't fit with the frame mods, but it was gonna need a full tune up anyhow; the plugs were pretty black, and I tore the carbs apart for deep cleaning before packing them away.  I'm more comfortable with fab work than engines, so it'll likely stay stock.

    To much time on your hands with nothing to do. Looks like a nice First Thursday bike.

    Winters here do tend to leave you with a few spare hours each weekend and a helmet on the shelf.  I have plenty to do, but this became an obsession that ate up most of my Saturdays.  Sometimes you start something and it just insists on being finished.  And yeah, its pretty much an event bike.  In theory it should be a decent daily ride, but I suspect the poepoe would find some issues with it.

    St.Paul.Slim


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    Re: Doing something funky in the (machine & welding) shop
    « Reply #4 on: November 30, 2015, 11:14:50 AM »
  • Sweet.  Can't wait to see the finished product.

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #5 on: November 30, 2015, 12:15:31 PM »
  • Sweet.  Can't wait to see the finished product.

    I'm hoping to be able to do a fire up and put-put in late May, and have it ready for the Bearded Lady show.  Given my typical work rate, both are extremely optimistic.  Its taken me 3 years to get to this point (though that's more like 100 shop days in my case).  However, I do seem to be getting faster at doing better work.  There's still a fair whack of fabrication to do (notably the steering and the front brake mounts) before its even a 'roller', and more (exhaust & intake, head and tail lights) before it might be roadable.  That ignores glamor items like rearsets, custom bars, etc.

    NorthStar


      "PhD in Braapanomics"

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    Re: Doing something funky in the (machine & welding) shop
    « Reply #6 on: November 30, 2015, 01:17:32 PM »
  • How did you figure out what steering geometry you wanted?
    In the face of danger, delight may tend to come across as psychopathic.

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #7 on: November 30, 2015, 01:40:00 PM »
  • In general I was shooting for a steep head angle (with conventional trail) and a strong dose of anti dive, with fairly constant rake and trail (maybe both increasing a bit) under bump.  Those are arbitrary goals, but seem decent for "real world" riding but still notably different from a conventional fork.  Pretty much is a test project along the lines described in http://tonyfoale.com/Articles/RakeEx/RakeEx.htm

    To achieve those I used Tony Foale's "Funny Front End" program.  Its made for exactly this sort of thing, graphs out rake / trail / anti dive against wheel travel based on input of numbers for pivot height above ground, arm lengths, wheel offset, bikes center of mass & wheelbase, etc.  I just plugged in numbers till I got graphs I liked, then did some further refinement to make the numbers match something I could practically build. 

    I think as its set up in the pictures the rake is currently steeper than I aimed for, and the trail to short.  Both should be easy to dial in.  My numbers as built don't match exactly what I have in the program, but the components I built allow adjustment for a lot of the important measurements and the behaviors tend to change gradually and smoothly over a pretty wide range of measurements, so I should get pretty close.  How that geometry will actually handle ... well, that's the point of building it.  And even then the geometry might well be fine and it would still work badly due to bad spring choice, to much unpsrung mass, etc.  A happy accident of construction is that the anti-dive is very easy to adjust, which is one of the parameters I really wanted to get an "ass on the bike" feel for, and one which doesn't depend at all on shock / spring setup or unpsrung mass (except as they affect braking power).

    « Last Edit: November 30, 2015, 01:55:23 PM by sebwiers »

    NorthStar


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    Re: Doing something funky in the (machine & welding) shop
    « Reply #8 on: November 30, 2015, 01:55:13 PM »
  • It would be interesting to see how it handles. Are you worried about flex at all?

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #9 on: November 30, 2015, 02:12:02 PM »
  • It would be interesting to see how it handles. Are you worried about flex at all?

    I'm more worried about strength, in the sense that I don't want it to fail and send me sliding down the road.  To that end, I'm gonna bolt the frame to a big ass steel saw horse I have and load it with simulated bump & braking loads that meet or exceed any reasonable load you'd see on the road (1g braking, 3g upward bump against front end load) plus a nice fat 100% safety margin.  If it can take that, I won't be worried about stiffness, no.  I certainly can't detect any slop or flex based on manipulating it by hand, which makes me happy.  I got pretty anal about combating slop, at one point shelving a bunch of precision bolts and machining my own tapers because there's no other reliable way to get a bolt to fit perfectly in a hole with no wiggle / ovalization under a heavy side load.

    It should be plenty strong, I used components that are grossly (like margin of 10x) over spec in most cases, and my fabrication went better than expected.  If anything, its probably overly stiff (and heavy), and will push more stress into the frame than the stock fork did.  If it proves strong enough, I'll probably get the setup dialed in and build lighter parts.  That would be easy to do just by eliminating the adjustable / modular construction.  Better material & hardware selection (and more $$$) would also go a long way.

    Even without flex, tank slappers can be an unpredicatabl problem, so I'll be hooking up a steering damper.
    « Last Edit: November 30, 2015, 02:41:34 PM by sebwiers »

    NorthStar


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    Re: Doing something funky in the (machine & welding) shop
    « Reply #10 on: November 30, 2015, 02:42:32 PM »
  • I see, I was more interested in flex during cornering. There doesn't seem to be much to prevent the front from flexing (twisting).

    I don't know much about it, but under hard cornering frames can flex. That's why they went to aluminum frames, they can use more material and make them more rigid.

    I ask because I want to make a similar project out of a pitbike.  It would be cool to have a small streetable grom-like moto.

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #11 on: November 30, 2015, 03:19:03 PM »
  • One of the main goals of this design (as stated by the original patent holder, Norman Hossack) is actually that its supposed to be stiffer / more twist resistant than a normal fork.  The logic is that the path from the contact patch to where the forces feed into the frame are shorter, acting over less of a lever arm, so there is less force acting on the frame.  A big stiff frame bracing the headset is pretty important when the wheel has a 3+ foot crowbar to apply force with; my crowbar is more like 2 feet.  The arms may look like a weak point, but pretty much the same setup (2 A arms) is used (turned 90 degrees) on your car to resist braking forces.  If they can safely hold half the mass of a car under 1g deceleration, I think they can resist flexing caused by pushing a motorcycle through a turn. 

    Some racing folks currently experimenting with this design are actually building in pivots that allow the fork to move side to side in a controlled and damped manner, to provide vertical compliance when going over bumps in a hard lean.  I think that is good evidence it can be stiff enough.

    Whether my specific implementation of this concept is up to par remains to be seen, but I'm pretty sure I could strap the frame down sideways and jump up and down on the fork with no worries.  I may actually give a more controlled version of that a shot, would be interesting to see if I can measure the deflection vs a 100 / 200 / 400 lb load.  On the other hand, I'd have noting to compare those numbers to...

    Assuming those side plates are anchored to something that won't twist, I'd expect its stiffer than a pedophile at the zoo, based on the general level of "overbuild".  The frame attachment points are not as good as a custom frame would allow, but seem decent.  I could maybe add more bracing, but at some point you gotta say when, otherwise you end up turning a tube frame into a really heavy monocoque.  The top mounting points are right at the lower end of the head tube, which should be one of the stiffest points on any bike.  The plates themselves want to stay parallel by virtue of the pivots for the lower arm riding on a 3/4" tapered solid stainless steel shaft bolted between those plates (plus of course the half inch bolts holding them to the frame).  Just behind that on the frame there is a new 1" cross member (the upper shock mount), which forms a nice triangle with the bottom of the headtube. 
    « Last Edit: November 30, 2015, 04:11:49 PM by sebwiers »

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #12 on: June 28, 2017, 09:45:21 PM »
  • Got my birthday notice from ZGEMPIRE today, figured I'd check up.  Noticed this thread hasn't been updated in a long time.  Lot of work between then and now, some parts (front shock mount) remade, some parts added, and the whole thing load tested for safety.

    Here's what it looks like now (or a month ago).


    I brought it home last week because the fab work is done (enough) and am working on electrical system, cables, fuel system, exhaust, etc.  Also got a steering damper for my birthday that will mount directly from the fork to the lower arm.

    « Last Edit: June 28, 2017, 11:36:02 PM by sebwiers »

    vince




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #13 on: June 28, 2017, 09:58:06 PM »
  • Looks like a First Thursday bike for sure this July.

    NorthStar


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    Re: Doing something funky in the (machine & welding) shop
    « Reply #14 on: June 28, 2017, 10:10:16 PM »
  • We need footage of you riding it.

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #15 on: June 28, 2017, 11:24:05 PM »
  • Looks like a First Thursday bike for sure this July.


    Won't be done by then, unless a crack squad wants to hit it for me.  Much as I'd love to hand some of the work off to a shop, I'm broke and no shop in their right might would take on the liability of helping make that thing ride-able. 
    Hoping to have it done by end of July.  Not really sure what local events might be worth taking it to, though July Firtst Thurs is obviousl an option.  Never been to one before!  The bike was made with events like Wasteland Weekend and the Mad Max run in mind.  I'd use it as a daily rider, but its probably never gonna be entirely legal.

    I've got footage of coasting it downhill with the engine not installed, but its really not very exiting.  Wasn't even set up right (almost zero trail) at the time, was just bolted together for display.  Really needs a go-pro next to the arms while it goes over some bumps.  Right now the brakes don't work, so that's not happening.  Maybe when I get the rear hooked up, I can push it down to the corner and roll down Ivy...

    « Last Edit: June 28, 2017, 11:34:51 PM by sebwiers »

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #16 on: July 14, 2017, 09:19:00 PM »
  • Am deep in the depths of electro-fuck hell.  Chopping the wire harness because I'm tossing the old dash unit, and getting rid of all the safety switches and relays in the process.  I figure I'll put the headlights on a switch so I can turn em off for starting.

    Pretty sure I had it wired up right to turn over, but it won't.  Fuckity fuck fuck.

    Anybody wanna lend a hand?


    St.Paul.Slim


      "The Ayatollah of Rocknrolla"

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    Re: Doing something funky in the (machine & welding) shop
    « Reply #17 on: July 15, 2017, 01:39:07 PM »
  • electric gremlins suuuuuck

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #18 on: July 15, 2017, 10:32:35 PM »
  • The do indeed.  This one turned out to be pretty simple once I slept on it.  Was wired up right, but the insulating washer on the starter lead was cracked.  It flexed enough to allow a short when the lead nut was tightened.  Fortunately I had a spare starter (whole spare bike) to swap on.  Washer can be replaced, but avoided a trip to the hardware store and the parts bike starter looks nicer.

    Bottom is the original (cracked washer removed), top is the parts bike.



    Now it turns over and the tail / brake lights work.  For legal reasons, still have to do license light (LED can patch in on tail light circuit), headlight, horn.  Would also like neutral indicator, obviously need to check that spark is good.  No turn signals for now.  Then I can actually start messing with trying to gas & start!

    Starter spin - https://www.instagram.com/p/BWk50I0DLcT/

    Brake light - https://www.instagram.com/p/BWlb0w7DrB2/
    « Last Edit: July 15, 2017, 10:38:20 PM by sebwiers »

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #19 on: July 15, 2017, 10:44:29 PM »
  • Hah, I forgot to share the pimp ass steering damper setup.  Because racebike.  Damper was a birthday present from the wife.




    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #20 on: July 19, 2017, 10:24:41 PM »
  • Lights, horn, spark all work.




    sebwiers




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    it STARTS!!!
    « Reply #21 on: July 21, 2017, 07:34:55 PM »

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #22 on: August 05, 2017, 10:52:17 PM »
  • It started on gas, but has problems running and likes to race.

    Is going in to Roy's Repair next week.  I'm not up to snorting gas fumes while I try to puzzle that out.


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    DVS_DAN


      "NVS of The DVS"

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    Re: Doing something funky in the (machine & welding) shop
    « Reply #23 on: August 10, 2017, 03:29:42 PM »
  • This is craziness.  It's alive!
    But I don't want greeting cards. I want to get fucked up on trampolines
    Pretty much everything that DVS_DAN said is correct.

    sebwiers




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    Re: Doing something funky in the (machine & welding) shop
    « Reply #24 on: August 10, 2017, 06:32:27 PM »
  • Damn straight.  Bad as it ran, I even took it around the block once.

    Just got back from dropping it off at Roy's Repairs to have the carbs looked at, because i'd just wreck them.  They are gonna dyno it, so I'll know just how little HP I'm dealing with.
    « Last Edit: August 11, 2017, 04:30:06 PM by sebwiers »


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