1215 Steel

[David2011]

For the things I make for the Battleship Texas restoration I’ve had the Foundation get 12L14 for most of the items that had to be steel and 4140 when strength or hardness was important. On a fluke I wanted to try 1215 for a complex part. They ordered a 2-1/2” OD piece from McMaster. Only important that it’s a reliable source. Pictures to follow. I have never machined anything as nice as 1215. Not even aluminum or brass alloys have been as nice. The most notable thing is that the cheap Chinese TiN coated inserts leave a beautiful finish at speeds that any lathe can achieve. A surface speed of 300-460 fpm is enough to get beautiful finishes and it responds well to the depths of cut and feed rates that small lathes can achieve as well as working well on bigger machines with aggressive feeds and DOCs. I made several passes at 0.100 DOC and the finish looked the same as lighter passes. It’s very forgiving and pricing is in the 12L14 ballpark. Highly recommended for anyone interested in trying a different steel alloy.

 

[Ischgl99]

I bought a variety of sizes of 1215 and 4140 to have on hand for the same reasons. 1215 is so nice to machine, but one of my steel inserts I have leaves a poor surface for some reason, but the rest machine it beautifully.

 

[WobblyHand]

I bought a variety of sizes of 1215 and 4140 to have on hand for the same reasons. 1215 is so nice to machine, but one of my steel inserts I have leaves a poor surface for some reason, but the rest machine it beautifully.

The only reason that I've found for poor surface quality on steel like 1215 or 12L14, is a chipped insert. The chip might be microscopic in size, but it's there. A fresh edge fixes the problem. If you use a 10x magnifier you'll see the chip. I'm now at the point that if the surface gets poor, I just automatically change the edge. 100% of the time, it's been chipped, but it's not always visible to the naked eye.

 

[rabler]

I've used 1215 and have to agree it is a delight to machine. Someone here has complained that it is more rust-prone than other alloys, I haven't had any problems in that regard but haven't used it in any likely to rust applications. I keep some from McMasterr in stock, have considered getting some larger stock pieces from my local metal supplier.

 

[rwm]

I just bought a big hunk of 1215 for the dividing head project. I guess I will find out about this! I have a lot of material to remove.

 

[Ischgl99]

The only reason that I've found for poor surface quality on steel like 1215 or 12L14, is a chipped insert. The chip might be microscopic in size, but it's there. A fresh edge fixes the problem. If you use a 10x magnifier you'll see the chip. I'm now at the point that if the surface gets poor, I just automatically change the edge. 100% of the time, it's been chipped, but it's not always visible to the naked eye.

I didn’t see a chip in the insert, but you may be right that it is small enough that I couldn’t see it. A good excuse to get a higher power magnifier. I’ll have to give that a try later.

 

[David2011]

My “good” Iscar inserts left an acceptable finish on 1215 at the DOCs and speeds listed above. The cheap Chinese inserts left a fantastic finish. I tried several different insets. The TiN coated ones all gave great finishes regardless of how cheap they were. The IC907 coated ISCARs and the generic dark gray TNMGs probably would give nice finishes with enough speed/feed/DOC experimenting but ”why bother” when there’s an easy solution at hand?

EDIT: Corrected ISCAR coating designation.