bolt so as to maintain a desired relatively constant friction coefficient between the threads of the nut and bolt since radial force on the spline tip of the bolt is used to tighten it a predetermined torque tension relationship is required the maintenance of a preset and constant friction coefficient between the threads of the nut and bolt is essential if for example a very high coefficient of friction was present torque would be developed faster than tension if on the other hand a very low coefficient of friction was present tension would be developed faster than torque to give an example of extremes if the threads were not the same type of threads on the bolt and nut binding would result developing torque very rapidly and breaking the tip of the bolt off before any substantial tension could be applied at the other extreme if a lubricant were used that substantially eliminated friction the bolt could literally be tightened by finger and the bolt could actually break off altogether before the spline tip because of the absence of resistance in accordance with the present invention predetermined tightening control is tailored to the customer the end user depending upon the thickness or the size of the channel or the particular application requiring more or less tension as before indicated there are two significant ways for controlling.