Turning cast iron, carbide or HSS preferred?

[Aaron_W]

I need to turn a couple of cast iron lathe chuck backplates. All I have at the moment is a set of 1/2" carbide insert bits. I do have some 3/8" HSS blanks I can grind.

I've actually never used carbide tools, other than boring bars. Also my first time turning cast iron. I gave a test cut on the cast iron and am not impressed with the finish, but there are a million variables other than the carbide that could be to blame.

If HSS is generally preferred anyway, then it is worth putting this aside for a day and grinding some tools. If carbide works better, then I'll spend a little more time getting things adjusted right.

Plates are for 6" chucks on a 10x24 lathe. This is the first real project with this lathe since getting it set up.


I can see why people don't seem fond of working with cast iron, it is like standing in front of a sand blaster.

 

[4ssss]

The carbide will hold up a lot better

 

[jbobb1]

When taking finish cuts, un-coated carbide seemed to give a better finish for me.

 

[mikey]

I would use carbide, too.

 

[Aaron_W]

Ok, it looks unanimous, I'll keep at it with the carbide.

 

[benmychree]

If one does not like to be sand blasted by chips, you can use a paint or chip brush to stop the stream and just let them fall into the chip pan; same goes for bronze chips. Unlike some, I like machining cast iron. A sharp tool with a small radius should give a good finish with a fine feed.

 

[darkzero]

CI is really abrasive & killer on HSS. It can be done though if you don't need to machine a lot of it & not in a rush. I don't mind machining cast iron, it machines nicely with no cutting oil needed but the mess & clean up sucks!

 

[stupoty]

I use almost exclusively HSS tools on my lathe, for cast Iron I use the brazed carbide type tools, they hold up pritty well to it's abrasive nature.

Stu

 

[mikey]

Aaron, you can use carbide inserts or brazed carbide. Even HSS will work but won't last as long. If you go with carbide, try turning the tool and use the edge right behind the nose radius on your finish passes - makes a really nice finish.

 

[Titanium Knurler]

Aaron, I just turned down a Shar’s D1-4 back plate for their set-tru-style ER-40 collet chuck the other day. This was my first time turning down a back plate and working with cast iron so I contacted Seco and asked for their recommendations. They recommended their CP500 carbide insert for cast iron, especially if there are interrupted cuts(screw holes) to contend with. I turned down the OD, face and adapter boss OD. Here are their recommendations and some photos:





Hope that helps