Helical Machining: Rifling with the Norris Chuck (TIS094)

This is a  helical milling apparatus but let me  first explain the name you know a lot of  drill Chuck's are mounted on Morris  tapers to facilitate inserting them into  a drill press and so we would call these  Morris chucks now this device uses a  small lathe chuck which because of its  size and because of the through hole in  the chuck has to be bolted to a  faceplate rather than mounted on a taper,  so 
since this device uses a chuck that  is bigger than a morris chuck .

Incrementing the first letter of its  name by one and calling it a Norris  Chuck seemed appropriate plus naming a  Chuck Norris just seemed fitting somehow  now let me explain how this works in  order to make helical cuts using my  milling machine  I needed a coupling between a linear  axis of the machine and a rotary axis .

Now originally my milling machine had a  hand wheel on each end of the  longitudinal axis but I find that I  really only use the one on the right  side so I took the hand wheel off of the  left side of the longitudinal axis and I  replaced it with a set of bevel gears  next I machined this aluminum housing to  hold a shaft perpendicular to the  longitudinal axis of the machine.

 I  mounted this to the machine using a  dovetail groove in the front of the  milling table that way I can slide this  back and forth the fraction of an inch  to engage either pair of gears and turn  the shaft in either direction relative  to the  rotation of the machine axis now when  that shaft rotates it turns a pulley and  I've got another pulley mounted in place  of the handle on a rotary table - which  has mounted that little lathe Chuck .

This  gives me the coupling that I need  between the longitudinal axis of the  mill and the rotary table so that I can  very easily machine helical grooves in  cylindrical work pieces now this device  has any number of applications one of  which is making rifling buttons so  that's what I'll be doing today  however before I machine the button I  need to make a new set of pulleys so  that I can get the twist ratio that I  want I'm just going to machine the  pulleys out of some 3/8 inch aluminum  plate .

Now as I've said before the fit up  between a rifling button and the barrel  has to be very precise in order to work  correctly and so it usually takes me a  couple of tries to get that fit just  right  that's why I'm making several rifling  buttons at once here all in slightly  different diameters so as to expedite  that process...

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