Unable to get the rifling I wanted from other sources, I designed and built my own sine-bar rifling machine.
A rack and pinion are affixed to a diagonal track (adjustable) and a linear carriage. The carriage houses the pinion gear and is rotated by the rack as they move up and down the I-beam. Since the rack can move in and out of the carriage, due to the angle of its track, the rifling cutter can be rotated to give a precise and repeatable twist rate.
The following pictures demonstrate the machine and rifling head as used for 2 of the Lukens barrels. I’m presently making the rifling head for the Girardoni rifles.
Here is the end view of the machine. The main frame is a 4″x4″ Al I-beam. The diagonal to the right is the sine-bar and is Al channel. These elements have linear guides attached for smooth travel. The Al clamp and rod closest to us is an end stop, adjustable for barrel length and twist. The next assembly is the carriage containing the rack and pinion. At the far end resides the barrel vise and indexer.
Here are the guts of the carriage. From left to right:
Carriage housing with linear guides at bottom, needle bearings pressed into bore and rack support extending to the right.
Pinion gear with torrington thrust bearing. The gear has a 1″ diametrical pitch, therefore 3.1416 ” of rack travel gives 1 revolution of the cutter.
Bronze bushing to seat gear and adjust endplay.
The rack is at the bottom of the picture. Continue reading Rifling machine
