Quoted from bimm25i:
Even if the ball is spinning on a horizontal axis like a top? I don't want to add speed to the ball with the spin I want to add sideways rotation
This is still tricky for a designer to control.
This might be a little more complicated to understand, but it will make sense.
The ball has a tendency to increase horizontal speed due to the fact you are a sloped playfield, even if this is not intended.
If you consider an equation of applied force in physics, any side spinning rotation is still translated as forward momentum because you are not on a flat surface or more simply meaning a percentage of the force is based on the applied angle of the playfield.
A child's toy top does the the same thing on a slope, it simply cannot stay in place, as earth's gravity is also additional applied as a force from acceleration (F=ma), in addition to translated downward force from the handle which translates downward force into rotational speed.
If a playfield (or mini playfield) is completely flat, this is theoretical possible to minimize the effects, but would require the playfield to be level with the floor and the surface being of extremely low friction, along with force only being applied from a spinning "buffer" wheel from the top of the pinball, not the sides. But, of course, you need some friction on a pinball playfield as well, or the ball cannot move while spinning, once the speed is reduced to zero, if the ball is away from the flippers. This is another reason why pinball playfields are sloped, to return speed to the ball, if the not being controlled by the flippers at any given time.
This is the concept of direction of the velocity vector which is alway tangential, coupled with acceleration based on the mass of the object, gravity, and surface friction.
It would be interesting to see the assembly apparatus used in this context, on a mini playfield that was horizontal away from the main playfield surface to see in in action.