Monday, June 22, 2015

Ball gates


The list of part that a pinball playfield need is endless.  I am already designing for months now, and I am still not finished with all the mechanical parts..


There are several type of gates. In the picture below is a wire gate.


They are used in places where the ball is not moving to fast. Faster balls could bend the wire.

There are also stronger gates that use a piece of spring steel to reflect the ball back. They are in places where the ball speed is higher when it hit the gate. For example on the end of the shooter lane.

image image


The wire gate

I like to make everything out of plastic for easy reproduction . So no metal bracket but a plastic one. The gate itself will be made using a metal wire, because this more easy absorbs and returns the ball energy.  And it is easy to fabricate too.

Here the 3d model. The plastic shape  strength is increased with the triangles behind the vertical parts.



The gate wire used is a 1.2mm thick stainless spring steel wire. very easy bend with a plier.


This are some test pieces made with soft iron wire to size the gate.  Below is the un-bended steel wire waiting its turn.

There the resulting wire gate.


For the photo I just stacked the parts. When mounted on a real playfield the right pin is more to the left, closed to the wire.

The firepower playfield needs two different gate sizes.



Stronger gate

The stronger gate I designed in plastic with a small piece of spring steel to absorb the ball force.

springgate3 springgate2 springgate1

The printed product


The pinball lays on the side of the gate, otherwise the would fall before I could make a photo!



But the design is not a 100% success.  It works, but can be improved. After designing and testing one, you understand why the gate are designed in the current way.

I planned to insert the spring steel vertically in the moving part and bent it 90 degree. No such luck – the used spring steel is just hardened too much: it just snaps . next time only use straight pieces of spring steel.

The issues with the gate are:

  1. The ball have to lift the gate to much: the change the ball got stuck under it is quite real.
  2. The weight the ball has to lift is too much too.
  3. The spring steel is to short.

So in the next iteration the moving part will be more balanced, lighter and shorter.

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