34 on the second retainer 32 by tightening the retaining bolt 35 the first retainer 25 and second retainer 32 pull the first drive shaft 11 and second drive shaft 12 into the tapered coupler 21 and into a mated position the tapered drive shafts 23 30 and internal splines 22 ensure that the coupler may be periodically re tightened without damage to the drive shafts 11 and 12 the shaft coupling 20 has the additional advantage that it may be manufactured using existing techniques well know in the art first a groove 23 a or 30 a about a half the depth of the retaining rings 24 or 31 is cut into the drive 10 shafts 11 or 12 then a tapered hobbing cutter is used to cut the tapered splines into the drive shafts the slope of the taper is approximately u215b inch per foot the retaining rings 24 and 31 are forced into their respective groove on the drive shaft to manufacture the coupler 21 a boring bar is used on a lathe to shape a tapered bore as previously discussed the diameter of the coupler is greater at the ends and is tapers gradually towards the center to cut the internal splines 22 a broaching tool is drawn through the tapered bore cutting the splines after the retainers 25 and 32.