The angle should be 30 degrees on a conventional grind. I’ve sharpened thousand of bits by hand during my career as a machinist and the video is spot on. The problem arose when we needed a hole to be exact. Getting the point in the exact center Is difficult by hand and can really be accomplished consistently by a dedicated drill grinder. If the point is off center, it will cut a larger hole. The other issue is grinding very small bits such as 1/16” and smaller. Also try resharpening a drill that you snapped off a half inch or so. Very difficult to re-establish the proper geometry by eye. We in the shop bought a dedicated drill grinder and once set-up properly made sharpening exact and very easy. I found an old General drill grinding attachment at a yard sale years back and use it on my bench grinder.
A note on cutting fluids. Early in my career we used “Cutting Fluid” which was petroleum based by the gallons. This stuff worked great on any milling, drilling or lathe operation, but smoked like crazy, and was difficult to clean up the machines after. In the eighty’s we started using both water soluble coolant on our larger drilling operations and 16 oz. cans of Rapid-tap on the smaller drill presses. The advantage to the water soluble coolants was it didn’t make a mess, cleanup was minimal and the fumes were tolerable. Imaging flooding a 3” drill bit with gallons of oil based coolant? Cleanup would be a job in itself not to mention the all of smoke coming off of the bit. It does not lubricate as well as an oil based coolant/lubricant but with larger machining operations it did the trick. The advantage to Rapid-tap and similar products is in addition to a lubricant they also contained a coolant that evaporated very quickly keeping the bit cool.
Just my two cents!
Last edited by Phak1; 06/29/2020 12:33 PM. Reason: Product correction
