The material you're drilling will usually be the determining factor of the angle the bit is sharpened. For regular non-hardened "mild steel" material that most of a stovebolt vehicle is made of, the usual 118 degree sharpening angle works well. Softer material such as aluminum or brass can tolerate a more pointy angle, while hard metals such as tool steel or drill rod need a flatter grind and a slower feed, plus some cutting oil or other lubricant. Here's an inexpensive set of sharpening guides that can be used with a regular bench grinder:

www.ebay.com/itm/158191994890?

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!