Rifled slingshot - first pics!

Discussion in 'Show off your homemades!' started by JoergS, Nov 20, 2013.

  1. JoergS

    JoergS Administrator

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    OK, started the build for real.

    The "barrel" is originally from... ahem... waste plumbing, the cheapest PVC tube in that size ebay listed.

    The wheels are from ebay as well, actually pretty cool, with true roller barings, 2,50 a pop.

    I wanted wheels on top for safety - after the motor has been attached (by means of a rubber belt), the thing will spin madly at 3000 RPM and I don't want this beast hopping of the table then :)

    The pressure of the wheels is actually adjustable. This increases safety but also friction.

    Will attach the motor next, then install the crossbow.

    [​IMG]

    [​IMG]

    [​IMG]

    This project gives the term "a rifled barrel" a whole new meaning, don#t you think) :)))
     
  2. VWscooby

    VWscooby Senior Member

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    Thats a lot bigger than I had imagined!

    EDIT: Just went back to original post and realised that I had mis-read it. Thought it said 25mm. 25cm makes more sense now! :eek:
     
    Last edited: Nov 20, 2013

  3. Moin moin,
    bin gespannt wie es weiter geht....
    -
    OK, das ihr beruhigt seit.... ihr erwartet ja kritik von mir ...... ich hatte mit einem Durchsichtigen Rohr gerechnet, das man das Bandverhalten innen drinnen besser sehen kann, die werden sich aber bei der Umdrehung, gegen die Röhre pressen... Gibt es die Röhre noch mit Farbiger makierung, das man im Mythbusterstyl mit der High Speed Kamera, die Umdrehungen sehen kann? Oder mit
    http://www.conrad.de/ce/de/product/...9999-Umin-optisch-mechanisch?ref=searchDetail

    Aber sonst müsste es wohl halten, wird bloss stark wackeln, aufgrund von unwuchten.... Gummilagerung?
     
  4. JoergS

    JoergS Administrator

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    Thorsten, I wanted to use Perspex (plexi glas) too, but for this poor video artist it was too expensive... 139 Euros at the cheapest supplier. This PVC thing was just 21,80, much more suitable for my budget!

    Stripes for my hispeed cam are easily applied with a sharpie, spray paint or duct tape.

    Uneven it is, it will shake quite a bit. But that is half the fun!
     
  5. Withak

    Withak aka Whitehawk!

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    I can't wait for the finished project. This should be a lot of fun :D
     
  6. Catamantaloedis

    Catamantaloedis Junior Member

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    This... is... gonna... be... AWESOME!

    Would someone please post the link to the original post, please?
     
  7. JohnKrakatoa

    JohnKrakatoa Loudest boom on Earth

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    Looks mad :D Are the wheels turn-able ? I would think that if they aren't fixed that it could hamper the function.
     
  8. JoergS

    JoergS Administrator

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  9. Antraxx

    Antraxx #7

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    What engine will you use to turn it?
    How do you prevent it from moving back and forward? Or do you think it will run stable enough? 3k is a lot man...i don´t think that´s possible. If the tube really makes it up to 3k the wheels will do what? 10k? lol
    But i´d love you to proof me wrong...Mr. Mad-Scientist "HAHAHA" :p
     
  10. Withak

    Withak aka Whitehawk!

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    I'm just glad that thing's in Germany. I don't want to be anywhere near it when it's loaded up and hits 3,000 RPM's :eek: Still can't wait to see the video though.
     
  11. flicks

    flicks ...lost in the woods....

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    Jörg, what I really like is that you always try to push the limits. I would love to see it working, but I share Antraxx' concerns. IF you manage to let the drum rotate at 3000 rpm you don't have to worry about a "hop from the table". A minor imbalance and you will shoot the waste pipe into the orbit. However, your video will be very entertaining - as always...:D
     
  12. JoergS

    JoergS Administrator

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    The tube has a thicker end (the rear side), and the way it is set up it will automatically move towards that end when turned clockwise.

    I will use my trusted power drill. That one has a max rate of 3000 RPM. The calculator says that 2000 RPM is enough for a stable spin rate of a 20mm steel ball at 40 m/s (SG = 1,51), so I hope that this is achievable.

    Yes, the wheels will turn at very high speed at that rate, but they do have ball bearings, not just bushings. They should hold.

    I do agree, this is all rather daring - but come on, it is NOT boring. That, and only that, counts.

    This is SHOW BUSINESS. Not product development.
     
  13. Antraxx

    Antraxx #7

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    Indeed it is and i´m really looking forward to the first tests!
    Don´t get me wrong it wasn´t my intention to go like those "it´s not worth the efford"-Guys.
    I was just curious how you will deal with certain stuff.
     
  14. VWscooby

    VWscooby Senior Member

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    :D That is why I like this forum!
     
  15. WildBill

    WildBill The Silly Song Guy

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    Woah... This should be epic.

    -Wild Bill
     
  16. Tremoside

    Tremoside SINdustrial designer

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    I was surprised when I've seen the rotating castors rigged to opposite directions without a radiax bearing nor axial support. Maybe that tube is not tested for ovality but sure it will be in-line as hell after the first hundred turns.

    Damn, it's exciting :D, but Jörg, please make a damn large killswitch and be careful!

    Fingers crossed :D
     
  17. OzzyOsborne

    OzzyOsborne New Member

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    This thing is gonna become some bastard Hadron Collider, creating a black hole in Germany that will suck the planet through it into a parallel universe, inhabited by Zombies.... Joerg, you have been warned....
     
  18. Tilia

    Tilia Junior Member

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    very curious about the result of this madness :D
     
  19. Tremoside

    Tremoside SINdustrial designer

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    SpinItSparta.jpg

    :d
     
  20. JoergS

    JoergS Administrator

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    @tremoside: lol lol lol (and this is the first time in five years of forum work I have typed these three words in a row)