Endmill Screw Torque

​You have to pay attention to the screw torque applied to side lock end mill holders. 

We tap-tested endmills in 1/2" and 3/4" toolholders, each at four torque settings. We used the manufacturer's recommendation, 25% less torque, 25% and 50% higher torque. We saw no difference in over-torquing (they are hidden behind the red lobe diagrams of the recommended torque. But, under torquing, showed in light blue, made a drastic difference in performance. FYI - recommended torques vary by manufacturer. In this case we used 24 ft/lbs for 1/2" and 36 ft/lbs for the 3/4". 

Our takeaway is to err on the high side when tightening the screws.