The entire bridge assembly should only take 12-15 pounds of force to move while making a cut, measured with a force gauge while cutting white oak with a 2-1/2 inch diameter bit taking 1/8 inch deep cut 1-1/2 inches wide. The units should have some resistance to motion, but it should not be tiring to handle a small project or unduly hard to move. The motion should also be smooth along the entire length of the unit.