I have the  3 piece carbon steel turning set that Rockler had on sale last year.  They stayed sharp a long time. 

If one edge dulls, you turn it to a new sharp surface. They are round, square and triangular.  Today I went to turn the round one and got an idea. I removed the cutter and placed it on my hand diamond sharpening tool. One side is course and the other fine. The tops and bottoms of these are perfectly flat. I placed the top (cutting edge) down and worked my way thru the course to the fine. It did a good job and I am pleased at the results. The sharpener is from Home Depot and cost under $20

Cool! I have a smaller version of the diamond tool. I'm going to give this a try!

Nice Tip Ron!

Nice tip to touch up the Carbide Cuters on those tools.

Carbide?

That looks like carbide.   Ya gotta use diamond on carbide.

is it this set?

http://www.rockler.com/carbide-mini-turning-tool-3-piece-set?utm_source=google&utm_medium=cpc&utm_term=&utm_content=pla&utm_campaign=PL&sid=V9146&gclid=Cj0KEQjwmNuuBRDTu5rDjr2kxJsBEiQAWlm6UvgXhEZzDaaMlp1uD0QvO2s-80uWRKDSYLn5XsrCPWYaAoEu8P8HAQ

 

There are tungsten and titanium carbide materials, there's no iron or steel in 'em.

 

Thats the set. I saw that Harbor freight has a s3 piece set of diamond hones for $10

I have been sharping them for a long time for my metal lathe.

I use the Green Silicon Carbide Grinding Wheels.