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  1. ChrisDuncan

    650-1100 pound torsion coil spring?

    This is like a garage door torsion coil spring. It drives a shaft with an ANSI 60 chain sprocket with a 3" pitch diameter. So I need a 1650 in/lbs torque spring. I miscalculated on the turns, it only needs to be 3 revolutions.
  2. ChrisDuncan

    650-1100 pound torsion coil spring?

    I need a torsion coil spring rated up to 1100 lbs. but design space is limited to 4" Diameter x 48" length. The range of motion needs to be 11 revolutions. Is this possible? If not 1100 lbs. then what is the maximum rate spring that would fit within this size?
  3. ChrisDuncan

    Calc of Worm Gear Efficiency

    Good info. This is a manually driven mechanism. A 19mm hand-crank shaft drives the worm. The worm wheel drives a 32mm shaft that goes to sprockets/chains which lift a varying load of 100kg to 500kg. ""bearing losses can be quite significant"" So guessing the choice is between ball/roller...
  4. ChrisDuncan

    Calc of Worm Gear Efficiency

    Also, trying to confirm what I'm thinking with the friction coefficient chart on the roymech page. If the output speed of the mechanism is .015m/s then the 10:1 worm sliding speed would be .15m/s? as the sliding speed increases the friction coefficient goes down? As the friction coefficient...
  5. ChrisDuncan

    Calc of Worm Gear Efficiency

    Worm Lead angle 14.7deg Worm Wheel Lead angle 11.5deg 0.075 friction coefficient How do you read this chart to calculate efficiency? http://farm8.staticflickr.com/7018/6597844643_211237d1dc_z.jpg the chart is also on this page 1/2 way down...
  6. ChrisDuncan

    Electric Car Conversion

    For about $10K you can get a used 2nd gen Prius (2004-2009). Then you can convert it to a "plug in" for about another $2000 to $3000. Essentially what you do is install another 2 stock battery packs, sourced from salvage. So 3 stock battery packs total. Then you install another programmable...
  7. ChrisDuncan

    Solid suspension bushings

    ""I do not favor the poly's because they are a kind of sticky plastic and during rotation they tend to stick to the axle of the arms and start to squeek."" Dow 111 works to lube poly bushings to stop squeek. Some of the better bushing kits are supplied with lube.
  8. ChrisDuncan

    The two-arm spirals

    I don't think SW is going to draw this exact profile automatically with helix/spiral. What you have pictured has a variable (increasing) pitch spiral. Helix/spiral in SW only draws a fixed pitch spiral. you can get the increase in the profile width by creating two spirals with different pitch...
  9. ChrisDuncan

    Need sample working drawings for 3d madelling

    Have been through this search myself There's IVWC (Inventor World Cup) which is PDF's of mech drawings of different objects. Click on the "IVNGWC (dated).zip" files. You can also dig through the contest results and see how fast some people can build things. This is good exercise because you can...
  10. ChrisDuncan

    Toyota uncontrolled throttle

    ""The wife's LS won't select neutral without pushing the little thingy....Then it quite easily goes all the way to reverse."" then I should modify my statement to say, the Asian vehicles I'm familiar with go to neutral without the release and reverse only with the release. From a safety...
  11. ChrisDuncan

    Toyota uncontrolled throttle

    ""Most if not all auto shifters will go from drive to neutral by merely pushing the lever forward. You don't have to push the release button. Also the shifter will only go to neutral when you do this. It won't go to reverse unless you push the release button."" What this also means is you do...
  12. ChrisDuncan

    Toyota uncontrolled throttle

    ""I tried to simulate the unintended acceleration in the wife's Lincoln (with her protesting, I might add). The engine rev limiter dropped the rpm to 3000/3500 immediately selecting neutral. Also found that the ECM will not allow reverse at speed...good to know."" The modern automatic shift...
  13. ChrisDuncan

    Toyota uncontrolled throttle

    I also think it could be some kind of outside interference. Like an ECU will become erratic if a large amp power wire is routed in close proximity, something about electro-magnetic fields. I've also seen cell phones clear immobilizer key chips when they are stored next to each other...
  14. ChrisDuncan

    Drive Shaft Disconnect Design Help

    OOmpaloompa, If you can please post how you solved this problem.
  15. ChrisDuncan

    Toyota uncontrolled throttle

    ""Bit of a bummer when your design works somewhere between 99.99 and 99.999% of the time"" It's probably a bit higher ratio than that considering only 20 or so fatal accidents. I think that's part of why it took them so long to come up with a fix, trying to duplicate or surmise the problem...
  16. ChrisDuncan

    Toyota uncontrolled throttle

    I think it's a "drive-by-wire" issue. Mechanical throttles reached near optimum refinement of design a long time ago. Electric throttles have not. Where in history has there ever been this type/magnitude of problem with mechanical throttles? This is a perfect storm of a problem probably caused...
  17. ChrisDuncan

    Puzzle

    If you can add force once in motion, without anything to push off of, why can't you add force from a standing start?
  18. ChrisDuncan

    Puzzle

    Compositepro, read the links in Bestwrench's post. The force is internal. It starts from rest when you move the small pendulum from the pivot where you grab the rope. You swing your legs back and forth and they gain angular momentum. Through timing and phase this is transferred to the larger...
  19. ChrisDuncan

    Puzzle

    "" but the bottom end of the rope will not necessarily stay under the pivot, and as soon as you have some inclination in the rope you have a source of a horizontal reaction, and the ability to move your centre of mass."" ""any offest between the bottom of the rope and the centre of mass will...
  20. ChrisDuncan

    Puzzle

    "no-one has answered where the horizontal reaction comes from" yes they did, pushing against friction of the pivot and possible air resistance "Everyone agrees that with a rigid rod it's possible to generate horizontal movement. A bicycle operates in a similar way in principle." a bicycle...

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