A fiew yeas ago I bought a Drill Doctor. I never took the time to set it up and use it.
I have been throwing bits that were broke, chiped or i had hand ground and did not get the angels just right into a bucket. Christmas week I got it out and sharpened a couple hundred bits.
It is very simple to use and I was realy impressed with the job it did.
I saved hundreds of dollars worth of drill bits.
The Drill Doctor I have is the older model 750. The new one is the 750X to replace it.
The diamond stone is not cheap to replace, about $25. but the stone that came with it is still good.
I did order a spare. The owners manuals has some good tips also. It tells that with large bits the center
point wears more than cuts and reccomends starting with a smaller pilot hole
Well worth the money.