Draw length extended steel slingshot

Discussion in 'Show off your homemades!' started by Yamroll2, Jul 12, 2013.

  1. Yamroll2

    Yamroll2 New Member

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    So, I've been working on welding together a pretty mean slingshot crossbow but decided to small scale it first to ferret out any unforeseen issues with the pulleys or the frame.

    What I wound up with is this, a smaller draw length extended slingshot.

    It's 3/4" hot rolled square tubing, welded up. The pulleys are actually climbing emergency sheaves for carabiners, made by petzl.

    My concern was the amount of play in the pulleys themselves. The pulleys have a 5/8" bore, but I wasn't really comfortable drilling a 5/8" hole in 3/4" tubing for the full size crossbow, so I drilled this one for 1/2" grade 5 bolts. The play in the system there definitely seems to increase the friction somewhat, but I'm satisfied from the small scale it'll work we'll enough for the final project.

    Overall length is about 48 cm with the handle about 30 cm from the front end for an overall extension of roughly 80 cm. It's currently racked up with theta tube red, though I have 25' rolls of all colours, so I might swap it out for blue this weekend.
     

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  2. 00Sven

    00Sven 14 jears old Member

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  3. Slagskimmer Mike

    Slagskimmer Mike thinks TBG smells better than roses

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    That looks like a blast.

    Sometimes when you buy a wheel for your bench grinder they give you a stack of plastic bushings with it. These are if the hole in the grindind wheel is too big for the shaft on your grinder.

    If your local hardware store has something like these it may trim out the slop in the pulley axle.

    Or use your power drill+belt sander to spin some quick adaptors.
     
  4. Will

    Will Thread Hijacker

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    This is great work and very well designed and built!
    I don't think it is legal in billiards tournaments however:D
     
  5. Yamroll2

    Yamroll2 New Member

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    That's not a bad idea. I manufactured some of my own bushings using a 3/8" inner diameter aluminium tube and some electrical tape (just to take up the space between the outside of the tube and the inside of the sheave) but actually found just having the 1/2" bolt inside the sheave with a touch of lithium grease spun smoother.

    It jiggles a little, but runs smooth, so hey. Works for me.