FILENAMES: Helical.jpg DESCRIPTION: This is a picture showing a helical gear being cut in a CNC mill. Posted by John Stevenson . John provided the following description: ================================================================= This file accompanies one called Helical.jpg The picture relates to a brass helical gear being cut on a CNC milling machine with a home made cutter machined as a 'D' bit. The cutter was made from a piece of silver steel [ drill rod ] from the details on making gear cutters in the Metal Web news article. The program was quite easy and actually consisted of one line that gave the angle that the rotary axis had to travel whilst moving the X axis. This is basically the lead angle of the gear. All formula's were obtained from the Browne and Sharp book 'A Treatise on Gear Cutting' This line was then repeated 37 times to finish up with a 38 tooth gear. The 4 gears required were cut off this blank by parting off. This 'quick and dirty repair' was to get a customer out of the proverbial 's**t' whilst he ordered some new gears. Needless to say they are still in and working.