It is not so much the impact speed that matters but the length of stroke. When considering an impact graver design, the piston in an impact tool is the hammer that hits
against a chisel. A short back swing with a hammer is going to deliver a more delicate impact than a long back swing will. A short back swing also takes less
time to execute than a long stroke. The AirGraver length of stroke collar is what this is adjusting. When the stroke setting is set extremely short the
back swing of the piston is only .010" of an inch. The piston will not have very much momentum or inertia moving a distance of .010", and therefore the impact will
be extremely soft and delicate. For the piston to move .010" takes little time, and that is why the impact frequency will be faster than at a longer stroke setting.
A longer stroke setting can be up to .375" for greater power in each impact.
My father's blow-pulse design and others like it on the market do not have a stroke adjustment. The AirGraver is a different tool because of the absence of internal spring.
Since it does not require running pulses through a piece of tubing there is uniform performance throughout,
with no “sweet spots” or weak spots. The full range of power and speed is "sweet" throughout, due to the internal and automatic balancing of air pressure for
both the impact and return strokes. This is why the tool will run from 0.5 PSI to 70 PSI and throughout the length of stroke collar settings. The patented
oscillation principle of the piston in the tool always stays balanced. In order to stay in sync with the wide range of PSI settings and the length of the
stroke settings, the tool takes care of impact speed frequency automatically, ranging from 1,500 impacts per minute to 15,000 impacts per minute and is always in sync.