Monday, December 28, 2009

"W"-slingshot: Ball Bearings added


the "W" slingshot, my best concept so far, has taken the next step.

I noticed that the rotating grip did not self center when a very strong band set was fully drawn out.

The rotating mechanism was just a steel tube that rotated around a thinner steel tube, the thinner tube beeing welded to the frame. It obviously had too much friction to rotate when the system was set under full pressure.

So I ordered some parts and enhanced the setup.

I added two ball bearings, originally from a motorcycle engine. I pressed them on the 12 mm steel rod that was welded to the frame, then pressed everything into a fitting aluminium tube (the grip). I cooled and heated the parts for the pressing. They are totally firm and there is NO play.

It works very well Now the grip rotates smoothly, even when I draw out my toughest bands.




  1. look great, i'm sure it really centers now.

    Maybe you should try some sort of crossbow style slingshot for your next one, that would be quite interesting to see.

  2. Rubber doesn't work well in a crossbow design, it tires out after just one minute or so. You have to draw out and release immediately. When you keep rubber in drawn out condition, it will loose 50% power after two minutes.

  3. Never knew that about Rubber...thank you.

  4. Good tip, so this method allows you to see when the new grease is starting to ooze across the top of the bearing?

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