View Full Version : black pipe

David Hafnorske
10-26-2002, 09:14 PM
A few years ago I tried to bore out the center of some black pipe. However because of the seam in black pipe that is hard I had limited success. I was using a HSS boring bar at full depth so It would just deflect rather than cut. Would carbide have helped any or would it still deflect?

Al Messer
10-27-2002, 07:40 AM
I don't know, but I'm facing the same problem: got to bore out some cylinders fabricated from black pipe in order to press in some cast iron liners. Sure hope someone can provide the answer!!!

10-27-2002, 11:02 AM
I don't believe carbide would have helped at all. It is in most cases not as sharp as hss and will just bounce off the seam.
When I had to do small pieces I used a drill bit then many passes with a bar with hss bits. It worked ok but I'm sure many folks here have a better answer.

Dr. Rob
10-27-2002, 11:19 AM
Um, how about an end mill in the tailstock? Tends to fix boring disagreements for me. Maybe that won't be accurate enough for your application, though. Don't know.

Al Messer
10-27-2002, 02:02 PM
I saw an illustration of an "Armouror's Bit" that had a block of wood attached to the back side of the cutter to keep it from going off course as it traversed the length of the bore of the cannon. Maybe something like that would work. Maybe you could machine out the first little bit of the seam with a regular lathe bit, and then use a snug fitting wooden plug around the shank of the boring bar to keep it at work and prevent it from deflecting. Or, maybe you could mount the pipe on the lathe carriage and bore out the seam with a very stiff boring bar turning between centers.

10-27-2002, 09:47 PM
A carbide insert boring bar will do it. I do this with 304 seamed stainless and it works fine. Set the tip slightly above centerline to help prevent digging in. A brazed tool will not be sharp enough. An end mill can be used as a boring bar if you want to "McGyver" it. Use as large an endmill as you can fit in the bore without interferrence.