Blue68f100
Member
I was in my shop and was going to turn some necks on my 224V brass and decided I did not want to change the settings on my K&M trimmer. So I decided to make me one. That was the easy part, the hard part is coming up with a way to precisely control the cutting tool. The cutting tool is made from 3/16" dia solid carbide rod I had laying around. Using my tool grinder with a diamond wheel I was able to contour the bit to match up to the 30 deg shoulder angle for most calibers. Locked in place with 2 set screws.
The only way I've come up with is to use apposing threads, RH and LH. I need to be able to buy the screw and tap in left hand. It's a PITA to cut metric threads on my lathe. And I do not like threading blind holes with no run out, my lathe does not have a brake. This limits my selection since most of what I'm finding is mainly 6-32, 8-32, 10-24, 10-32, 1/4-20,28,40, 5/16-18,24 and a few Metric M4-0.7mm, M5-0.8, M6, M7, M8-1.0mm. A LH 1/4"-40tpi (0.0025") and RH M4-0.7 (0.02756") which yields 0.0025", but runs backwards. There are quite a few combos that give me ~0.004"/turn. It would be nice to have 1 turn = 0.001" But it looks like that is not really practical with whats commercially available.
I will probably solder or epoxy the thread to the cutter. Being carbide, threading/drilling it is not an option for me. I don't have a EDM machine.
Lets see what the engineers in this nice group can come up with. I know there is something I'm missing.
Calling our resident Master Builder JMorris....
The only way I've come up with is to use apposing threads, RH and LH. I need to be able to buy the screw and tap in left hand. It's a PITA to cut metric threads on my lathe. And I do not like threading blind holes with no run out, my lathe does not have a brake. This limits my selection since most of what I'm finding is mainly 6-32, 8-32, 10-24, 10-32, 1/4-20,28,40, 5/16-18,24 and a few Metric M4-0.7mm, M5-0.8, M6, M7, M8-1.0mm. A LH 1/4"-40tpi (0.0025") and RH M4-0.7 (0.02756") which yields 0.0025", but runs backwards. There are quite a few combos that give me ~0.004"/turn. It would be nice to have 1 turn = 0.001" But it looks like that is not really practical with whats commercially available.
I will probably solder or epoxy the thread to the cutter. Being carbide, threading/drilling it is not an option for me. I don't have a EDM machine.
Lets see what the engineers in this nice group can come up with. I know there is something I'm missing.
Calling our resident Master Builder JMorris....