Schedule 80 Steel Pipe

[deadin]

I was planning on using a piece of Sched.80 pipe to make a cylinder sleeve for an IC engine
The problem is I can't seem to get a decent finish on it in the lathe. I've tried carbide and HSS bits, varied the speed, feed and tool height and just can't get a smooth finish. It comes out with bands of clean cuts and then a band of rough cut.
Is it me or the pipe??? I don't want to start boring the inside diameter until I can get something that resembles a smooth enough surface for honing and lapping.

Dean

 

[stevehuckss396]

It's most likely the pipe. Get a bar of 12L14 steel and you won't want to ever use anything else.

 

[Loose nut]

Pipe is crap material and is usually hard to get a good finish on, not impossible but hard, it tends to dig in a lot leaving an uneven finish. You can try different speeds and feeds it may help.

 

[Deanofid]

Some pipe just doesn't turn all that nice. If you want to use something like pipe, get some
DOM tubing. You can get a decent finish on that. Even better to use a more common material
for cylinder sleeves, like CI.

 

[Brian Rupnow]

A word of warning---I am told that 12L14 if very prone to rust. Internal combustion engines create a lot of water as a byproduct of the combustion process. Yes, pipe is crap quality steel, very difficult to get a good finish on.

 

[GWRdriver]

I've gotten decent finishes on Schedule 40 steel pipe, but it wasn't easy. The photo is of one of the first roughing cuts on a 6.60" diameter locomotive smokebox and I don't know what the material was, whether water pipe, mechanical tubing, or structural tubing. The alloys and therefore the finishing characteristics will be different. Several test cuts were made until I got a tool/speed/feed combination which would make a continuous cut. IIRC the finishing tool tip was first a good HSS ground to a very small round-nosed "spoon" shape with a ton of back rake and honed to within an inch of it's life. The turning and feed rpm's were quite slow and I eventually found that the cut went best with a smear of my tapping fluid which is Tap-Magic. I don't recall the depth of cut but my guess would be maybe .005". It took three passes to get one without a score and in the end I got the finish I was hoping for.

As you can see the tube is larger than the chuck so I pushed it back over the chuck jaws a bit but the setup still essentially created a "bell" which did ring, that is, a harmonic appeared which caused faint rippling in the finish, a form of chatter. Stuffing a wadded up towel in the tube on the final cuts dampened things sufficiently to remove the harmonics and eliminate the ripple.

 

[Deanofid]

A word of warning---I am told that 12L14 if very prone to rust. Internal combustion engines create a lot of water as a byproduct of the combustion process.

I have first hand experience with 12L14 as a cylinder for an IC engine. Rust is no more a problem with it than with any steel. The cylinder and head I made from it
nearly 15 years ago are still on the running engine. No rust. It may simply depend on you're ability to put on a decent finish.