- Joined
- Feb 1, 2015
- Messages
- 9,622
In the process of installing an electronic lead screw on my G0602 lathe, I measured the amount of torque required to turn the lead screw with the half nuts engaged. I was rather surprised to find it took over 400 oz.-in. of torque to move the carriage with no cutting load. In investigating the cause, I discovered that when the half nuts were engaged, they gripped the lead screw tightly. Backing off the half nut lever very slightly, that torque reduced to 200 oz.-in. My immediate thought was to put a shim in place to prevent the half nuts from closing so firmly.
I pulled the apron off and it appeared the best way to control the closure was to put an adjustable stop for the half nut cam (P/N 142). On closer inspection, I noticed a hole immediately below the thread dial. Looking further, the hole went through to the casting and was threaded.
OK, I determined the thread was an M6-1.0 mm. I found a couple of M6 set screws and ran them in the hole, the first setting the stop for the half nut crank and the second as a lock for the first screw. The required torque is now more manageable at less than 200 oz.-in.
It appears that the threaded hole was originally designed as a stop for the half nut cam,; I can't think of any other purpose. Some bean counter probably thought they could save a few Yuan if they omitted them when they cloned the lathe.
Aside from reducing wear due to an overtight half nut, the reduction in torque would reduce the load on the motor by around 1/4 hp. when using power feed.
I pulled the apron off and it appeared the best way to control the closure was to put an adjustable stop for the half nut cam (P/N 142). On closer inspection, I noticed a hole immediately below the thread dial. Looking further, the hole went through to the casting and was threaded.
OK, I determined the thread was an M6-1.0 mm. I found a couple of M6 set screws and ran them in the hole, the first setting the stop for the half nut crank and the second as a lock for the first screw. The required torque is now more manageable at less than 200 oz.-in.
It appears that the threaded hole was originally designed as a stop for the half nut cam,; I can't think of any other purpose. Some bean counter probably thought they could save a few Yuan if they omitted them when they cloned the lathe.
Aside from reducing wear due to an overtight half nut, the reduction in torque would reduce the load on the motor by around 1/4 hp. when using power feed.