Buckshot
11-15-2006, 05:08 PM
http://www.fototime.com/63A351DE0EBB0B9/standard.jpg
Centering the diehole on a faceplate.
http://www.fototime.com/E02C7E1C390E32C/standard.jpg
Clamped in position and a counterweight bolted in place.
http://www.fototime.com/82E4FAD8CC35101/standard.jpg
Beginning to bore to size. In this case for a 1-1/4-18 thread.
http://www.fototime.com/07A1C1C51FF349D/standard.jpg
Threading. I had made this boring bar as one of the first projects when I got my lathe. It's designed to hold 1/4" round bits. In this case a bit ground to cut threads. Since I'm cutting internal threads, and due to the junk hanging on the faceplate (clamps, bolts, counterweight) I'm cutting away from the faceplate. With proper counterweighting and threading away, the spindle may be run at a comparatively high rpm for threading.
The bar is extended just enough to clear the inside of the hole so the compound can be advanced before the halfnuts are engaged. The compound is rotated around to the backside so the bit may be advanced into the work. The spindle is run in reverse and the leadscrew in the forward position so it also runs in reverse.
Since the workpiece is cast iron, the threading is done dry. I really dislike working with cast iron as it's a pure mess. The 18 pitch threads in a hole this size are pretty fine, but the high quality cast iron in this toolhead allowed them to point up fairly well and it turned out good. Took longer to clean the lathe up afterwards of all the cast iron dust then it did to do the work :-)
................Buckshot
Centering the diehole on a faceplate.
http://www.fototime.com/E02C7E1C390E32C/standard.jpg
Clamped in position and a counterweight bolted in place.
http://www.fototime.com/82E4FAD8CC35101/standard.jpg
Beginning to bore to size. In this case for a 1-1/4-18 thread.
http://www.fototime.com/07A1C1C51FF349D/standard.jpg
Threading. I had made this boring bar as one of the first projects when I got my lathe. It's designed to hold 1/4" round bits. In this case a bit ground to cut threads. Since I'm cutting internal threads, and due to the junk hanging on the faceplate (clamps, bolts, counterweight) I'm cutting away from the faceplate. With proper counterweighting and threading away, the spindle may be run at a comparatively high rpm for threading.
The bar is extended just enough to clear the inside of the hole so the compound can be advanced before the halfnuts are engaged. The compound is rotated around to the backside so the bit may be advanced into the work. The spindle is run in reverse and the leadscrew in the forward position so it also runs in reverse.
Since the workpiece is cast iron, the threading is done dry. I really dislike working with cast iron as it's a pure mess. The 18 pitch threads in a hole this size are pretty fine, but the high quality cast iron in this toolhead allowed them to point up fairly well and it turned out good. Took longer to clean the lathe up afterwards of all the cast iron dust then it did to do the work :-)
................Buckshot