12-21-2013, 12:34 PM
I went over to the shop, got out my Starrett C19 protractor and using a pencil I scribed 20º (40º included) and 14.5º (29º included) triangles on a piece of paper. The gear teeth in the borrowed 70 tooth gear seemed to line up with the 20º pressure angle, so I guess that's what it is.
Being the holiday season I don't have funds to buy a 6" chuck for my rotary table nor a gear tooth cutter and arbor (though I could make one of those), so I'm going the cheaper route and get someone on PracticalMachinist.com to cut the teeth in a blank I'll make.
I checked the gears I have in the machine right now, they are 127, 105, 50, 25, and 20. With the added 70 tooth gear, I'll be able to cut metric thread pitches of 0.25, 0.5, 1.0, 1.25, 1.5, 2.0, 2.5, 3.0 and 5.0. Adding the 30 and 35 tooth gears later will get me 0.75, 1.75, 4.0 and a couple others. Not on the list would be 0.7, but I doubt I'll need to ever cut an M4x0.7 thread that I couldn't cut with the dies I have.
Switching the machine out to cut metric gears should be simple, but on this machine I have to remove the toothed wheel for the 5C collet closer. Indicating it back into running true is a big PITA, so I will use dies for most metric threads I may have to do. All that until I get the shop moved and can install and run the YAM CNC lathe that Russ is giving me. With that machine, no restrictions on threading, and for once I'll finally be able to cut pipe threads without a die! My Victor 1640 lathe doesn't have the no-longer-available taper attachment, and the last one the importer had sold for over $1,700. Even if they had one, it wouldn't be me buying one at that price. If I ever find one of these lathes that has it, I'll see if I could reverse engineer the assembly and make my own. The taper attachment and having two other gears, 28 and 35, would allow me to cut 27 pitch imperial threads.
Being the holiday season I don't have funds to buy a 6" chuck for my rotary table nor a gear tooth cutter and arbor (though I could make one of those), so I'm going the cheaper route and get someone on PracticalMachinist.com to cut the teeth in a blank I'll make.
I checked the gears I have in the machine right now, they are 127, 105, 50, 25, and 20. With the added 70 tooth gear, I'll be able to cut metric thread pitches of 0.25, 0.5, 1.0, 1.25, 1.5, 2.0, 2.5, 3.0 and 5.0. Adding the 30 and 35 tooth gears later will get me 0.75, 1.75, 4.0 and a couple others. Not on the list would be 0.7, but I doubt I'll need to ever cut an M4x0.7 thread that I couldn't cut with the dies I have.
Switching the machine out to cut metric gears should be simple, but on this machine I have to remove the toothed wheel for the 5C collet closer. Indicating it back into running true is a big PITA, so I will use dies for most metric threads I may have to do. All that until I get the shop moved and can install and run the YAM CNC lathe that Russ is giving me. With that machine, no restrictions on threading, and for once I'll finally be able to cut pipe threads without a die! My Victor 1640 lathe doesn't have the no-longer-available taper attachment, and the last one the importer had sold for over $1,700. Even if they had one, it wouldn't be me buying one at that price. If I ever find one of these lathes that has it, I'll see if I could reverse engineer the assembly and make my own. The taper attachment and having two other gears, 28 and 35, would allow me to cut 27 pitch imperial threads.