Frame geometry

Important parts of the frame are the location where the contact
screw is located in relation to the tube vise hole, and its overall
geometry. The overall geometry is the location of the holes that
are tapped in the frame in relation to one another. These holes
are arguably supposed to be in perfect alignment to create optimal
magnetic pull on the armature bar. The rear spring will attach
to the back of the frame, thus controlling where the front of
the armature bar will end up. If this geometry is not in relatively
perfect alignment then the armature bar nipple will not move directly
above the tube vise hole. This also goes to say that if the
holes are not in alignment, then the armature bar will not be directly
above the coil cores. When an armature bar is not directly
above the coil cores, maximum efficiency of the electromagnets
cannot be achieved.