JA, BD, CC, Whitefish or anyone else with the knowledge have a good procedure for correctly resharpening multi faceted bits ( fig.e) on a pedestal grinder? Is it possible or am I asking for trouble? You also have to wonder what to do with a candlestick ( fig. c) bit as well .

I know the lips and relief angle clearances have to match as to not drill over sized holes.

These are called DRILLS. A BIT is something you put in a horse's mouth.

Style (a) can be easily sharpened in a pedestal grinder. Maybe style (d), but for the rest, thry need to be sent to a cutter grinder.

Style (b) needs to have the length of the pilot held, style (c) would heed to have the shapr dressed into the grinding wheel. Style (e) might work if you have a sharp corner on yout grinding wheel. You couls probably sharpen style (f) if the hole is deep enough, but if the hole is deep enough, then the flutes would be really flimsy.

I only use two types of drill points in my tool room. One is the standard 135* split point drill type & the other is the four faceted type drill point. I use the four faceted point on difficult to drill materials. C-2 carbide drills that can easily drill Rc 65 tool steels are also four faceted. I never use standard point drills that "auger" the metal out of the middle & need center drilling to prevent drill walking when starting. These type drills also generate very high heat when drilling. The other two drill points cut from the middle & do not require center drilling when starting. The four faceted drill point generates very low heat & therefore can be used in very difficult to drill alloys.

Split point drills can be sharpened in the surface grinder with a simple indexing fixture. Faceted drills can easily be ground by hand. Things to watch for include uneven lands, different land angles, overheating & clearance angles when re-sharpening.

There is also a six faceted point drill type that is even more durable than the four faceted drill point type. All of this information is available on the internet.

I posted a photo of a four faceted drill point & a 135* split drill point.

JA

JA, Ive read the 6 faceted drill is the least utilized and has the most durable point.The also generate less heat than orther type drills in the same diameter.. I also skimmed across some jigs that should make resharpening easier. I doubt you do it with a Jig. At your leisure, if that exist, please pass a few photos of what you use to do them.

4 point faceted

6 point faceted

The 6 faceted drill point is impossible to grind by hand, but the 4 faceted drill point is easy, even in small sizes. Small sizes require magnification & rigid mounting of the drill in a machinist grinding vise like the one shown. Secure the vise base, use a diamond disc (Dremel type will work nicely), a slower speed & a purchased faceted drill as a model. Measure the length of the lands, position the drill in the same way & grind. It will take some practice, but evidence of a properly ground piece is: no center drilling required, very little pressure is required to drill even Rc-65 steel pieces; the curly chip should be the same on both sides & the drill will stay sharp indefinitely.