I'm working on a design to feed Airsoft BB's through a funnel. A simple gravity fed system (ie. I don't want to force them out at speed) but every now and again the BB's get jammed at the end of the funnel.

I would like to use a motor to constantly keep the BB's moving and prevent jams.

The video below highlights the issue:


I would welcome any tips to improve the design/make it functional.

At the moment my thought is to add ridges to the inside of the funnel, this combined with the mixing action should shift them around enough to prevent the jam?

  • $\begingroup$ Take a look at paintball, tennis ball and other hoppers for design ideas. Just looking at your video I would put a rib or 2 in the funnel so that the bb will be forced to move by the paddle instead of spinning around smoothly. $\endgroup$ – Drew Apr 30 '20 at 6:25
  • $\begingroup$ Hi Drew, agree with the ribs in the funnel! That's my next move. Tennis ball hoppers is also a good idea, something to explore! Thank you $\endgroup$ – Jake Howard May 1 '20 at 7:08

What I've seen in commercial applications of this nature involve a vibrating device, which dislodges the stuck balls. It causes random movement within the block or pack of balls and helps to disorganize them enough to allow movement.

From the video clip, you'd want something to move the block in the center out of the way, even just a tiny amount.

Have you considered an oscillating motor to rock the spinning motor through a small angle, similar to an inverted windshield wiper travel? The pivot could be at the end of the gantry holding the spinning motor causing it to rock back and forth, perhaps only a couple of millimeters at the spinner end.

Consider also that an increase in size of the exit will improve the process. For "single file," one needs only to be smaller than twice the size of the ball.

  • $\begingroup$ Thanks for the reply, I certainly think vibration could be a good way forward. I've ordered some small vibration motors that you get in mobile phones. Hopefully a couple of these near the end of the funnel will be enough $\endgroup$ – Jake Howard Apr 28 '20 at 7:08
  • $\begingroup$ I've added another suggestion to the answer. $\endgroup$ – fred_dot_u Apr 28 '20 at 9:04

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