As I've not got a Drill Doctor (yet), is it possible to sharpen a drill bit by hand please, say by holding a spinning bit against a grind stone?
TIA
TonyW
Safest method I can think of to RELIABLY sharpen a drill bit equally for both chutes is to chuck it in a 3-jaw chuck on your lathe or drill press securely, and gently touch up the cutting edges with a diamond card or plate while it spins at high RPMs .... keep water on the diamond card/plate for cooling.
If you are VERY steady with your hands, you could try using a grinder or sanding station to touch up the very tip of your bits ... make sure the grind stone has been freshly dressed so that it cuts a good clean swathe, or if you are using sandpaper, fresh would be best.
You could theoretically do the same via use of a Dremel and some grinding tips or sanding discs ... the issue with these two methods is that you could take more material off one side than the other, leading to that flute being the only leading edge, which will cause the bit to want to cut in that direction ....
This cutting more in one direction doesn't do much if the BIT is spinning in a hand drill or a drill press .... but when the bit is STATIONARY while you are drilling on a lathe, the bit will tend to wander in the direction that it wants to cut in, resulting in flexing the bit in that direction, possibly bending the bit, giving you an oversized hole, possibly breaking the bit, causing the bit to get stuck in the hole when you try to clear chips, overheating, and dulling the single cutting tip very fast. (All these problems come lumped together, good luck!)
The first method, where you spin the bit and touch up the cutting edges, is probably the most reliable method to get an even cutting edge .... but you'll still need to touch it up by hand by giving the cutting edges of the bit a relief angle, in order for that cutting edge to be able to dig into the material you are drilling into, rather than just riding on the surface area of the drill bit tip and just getting very hot.
In order to do this, you can keep the bit in the lathe or drill press if you are comfortable with the working angle, or take the bit to a vice and clamp it securely ... then take the same diamond card or a good file, and WITHOUT TOUCHING THE VERY EDGE, add an extra 5 to 10 degree sweep back from the edge to allow for the edge relief.
If you can do all of this by hand, you're on par with a top machinist .... (they buy drill doctors for a reason!)
The way a Drill Doctor works is simple .... the bit is clamped within the flutes, which gives a guaranteed cutting angle against the tip. All standard style twist bits have the same proportional makeup, so the clamping system is spot on every time, guaranteeing that you only remove minimal material from the tip each use.
As you ROTATE the bit by hand, the clamping bit holder is made to ROCK and change it's angle as you turn it. This allows for sharpening the cutting edge of the bit AND grinding the relief angle in a single motion for every pass .... you rotate the holder until you hear little to no grinding action for full rotations ... this means that the cutting edges are even and equal on both sides and the relief angle has been met.
If your Drill Doctor has the split point port, it can only be inserted in 2 different orientations .... use BOTH and grind both sides evenly ... examine the point of the bit to ensure that there is sufficient material in the center of the bit for strength, and that your cutting edges have been split well to discourage wandering in the bit cutting action.