The tool room was locked up but I found a chipped drill the right size (2 5/8" dia as I recall) in a drawer. There were plenty of suits and white hats present emphasize the job’s urgency. Story: I once was called in to work on a Sunday to drill some big holes to layout in a thick piece of steel plate using a monstrous radial arm drill. That's what sleep is for, to rev and mod the brain’s software. When you sleep your brain will re-program itself and you'll do better the next day. They make drills long so apprentices can practice sharpening them. If you don't do sharpen a drill perfectly the first time, don't worry about it. The skill lies in the reflex loops you develop not conscious thought. It's like riding a bicycle or catching a ball. You cannot verbalize free hand-drill sharpening except as a means to get the beginner started. Sharpening drills is a manual skill requiring practice and training of the neuro-muscular system. It takes but a few minutes and you have much better control over the angles and other features. I might touch them up on a bench grinder but I finish them with a hand stone. Smaller drills – those 3/16” and under – I free-hand sharpen with a hand stone. There’s nothing to keep you from doing it except the cost of the drill (low) and the number of sharpenings the drill can endure (many) before it gets to short for use. When the need arises you may wish to grind a special point on the drill. Different materials might call for special cutting angles and clearances which may be found in appropriate technical references. You need to be close but it’s more important for the drill point to be centered, symmetrical, and equal angled in its two cutting edges. There is no need to slavishly adhere to the 118 degree included drill point angle. If you get two unequal chips maybe not so great but if the hole is less than 0.005" over nominal you did good. If not, no harm is done sharpen it some more until it’s right. Grind the drill through several indexes stopping to check the lip angle, symmetry, and clearance. Check the parallelism of the lip and the angle with the edge of the tool rest then immediately grind. You'll be surprised how accurate and repeatable these neuro-muscular maneuvers are when not interfered with by a worry-wart brain. Let your senses tell you when the drill is properly indexed. Just give it a quick rotation with the hand and re-cradle it as you resume your grip. Index the drill in your fingers to grind the next lip without thinking about it too much. If the drill needs more clearance start the lift sooner. If the clearance is excessive don't lift the drill so high. Lift the whole drill up without rocking or rotating it and follow the drill in. It makes you stoop and throws off your stance, the clearance angle, and often your parallelism to the wheel face. Do not rock the drill shank down to grind the clearance. Touch the drill to the wheel periphery and after a second or two lift up to grind the clearance angle by following the wheel. Go through a few preliminary sharpening motions to ensure the repeatability of your stance and your grip on the drill. If you have to twist or distort your body your drill sharpening will reflect it. If your stance is right your indexing and presentation is almost automatic. Present the drill to the wheel and adjust your stance so the lip is parallel to the tool rest and the angle is parallel to the wheel's periphery. The fit of the drill in your right hand registers it when you index (rotate the drill precisely ½ revolution). Hold the drill comfortably so the flutes cradle themselves in your fingers of your right hand and with the shank in your left. Here's how:ĭress the grinding wheel straight across so its periphery is a near perfect cylinder.Īssume a firm comfortable stance in front of the bench grinder. All it takes is practice and some experimentation. If your skills are well developed you can free-hand sharpen drills by eye alone. If you use a common bevel square or a drill gage to get the lip angles equal and a pair of dividers to get the lips symmetrical you can do an excellent job of drill sharpening free-hand. I grind drills free-hand even now as a blurry-eyed old guy. Hand sharpening: Fancy drill sharpening gadgets aren’t always available. A carpenter's bevel gage and a divider is nice to have. All you need is a good bench grnder and a good eye.
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