First off I don't want to start a shouting war of "Tastes Great" vrs "Less Filling".
As a (former) firearms manufacturer I researched barrel manufacturing methods in depth after being ask to reproduce a replacement barrel for a long since out of production item. The Hook and pull (sine method) was developed back in the black powder days when steel was soft and bores were large. Keep in mind that one reason a single groove is cut has to do with chips in the bore. The cutter often takes less than .0002" per pass. Early machines could easily be hand powered, albeit a long monotonous process. Because of the time factor Enfield actual made some barrels with only 2 grooves. As bores got smaller 6.5mm became about the smallest bore that could be produced reliably with current materials. During WWI material science improved. The cutter is often held straight in larger bores and all twist timing is done externally. Button rifling on the other hand relies on the angle of the flutes of the button to control twist rate. Button rifling is like a swaging operation because no cutting takes place. Broach rifling is like button rifling in that the twist is controlled by how the broach was ground, but the grooves are cut, not pressure formed. If this were attempted with LCNC I think it is an application which begs for absolute encoder support. Any loss of position while in process would likely destroy both work piece and the cutter and cutter carrier unless machine was dis-assembled to allow removal of work and cutter assy together so tool could be backed out by hand. The beauty of the original design is that short of taking a chuck key or wrench to the machine it is nearly impossible to get out of sync. Greg Bentzinger ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
