an offset angle u03b1 u2032 the offset angle u03b1 u2032 is calculated by u03b1 u2032 90 u2212 arctan x u2032 y u2032 where x u2032 is the horizontal distance 68 u2032 and the y u2032 is the vertical distance or gain 56 u2032 in this embodiment the vertical distance or gain 56 u2032 is approximately 1 25 times longer than the horizontal distance 68 u2032 as such y u2032 1 25x u2032 accordingly this changes the formula to u03b1 u2032 90 u2212 arctan x u2032 1 25x u2032 or u02dc 51 34 u00b0 when comparing the two embodiments disclosed herein fig5 illustrates u03b1 u02dc 26 57 u00b0 and fig8 illustrates u03b1 u2032 u02dc 51 34 u00b0 the difference in the offset angle u03b1 u03b1 u2032 is then represented by the difference in the magnitude of the force vectors applied at the drive point 62 namely the horizontal vector 64 of fig5 is relatively larger than the horizontal vector 64 u2032 of fig8 and the vertical vector 66 of fig5 is relatively smaller than the vertical vector 66 u2032 of fig8 this is because of the increased offset angle which drives more of the force downwardly in fig8 so the strike line 60 extends through the drive point 62 as opposed to some point offset therefrom which may create an undesired moment of course as described above the drive point 62 could be moved along the length of the rasp 54 depending on the desired drive point.