I had to get a new round tip for my tool. I found out that carbide don't hold up well when it hits a turning chuck. I turned the tip and it worked fine till I hit the chuck again. I am known to jerk when I am surprised. My wife knows to knock before she comes in, however, she forgot 

 

Any way, I have found an easy way to keep a good edge on these tips. Harbor Freight has a set of 3 diamond dust sharpening pads. Course Medium and fine.

I don't allow them to get very dull before I remove them, place the flat cutter down and go thru the pads. I use moderate pressure and doe a good job.

Great tip Ron! Ya, carbide and iron don't mix too well when contact is made does it!

I use these. Basically the same thing. I usually do the sharpening with the cutter still on the tool.

 

I like to have it laying as flat as possible to insure even sharpening on all cutting surfaces/edges.