Once upon a time, I was in a vo-tec program for tool and die makers that was a feeder school for Boeing. One of our first subjects to study were twist drills. There are multiple faces on a twist drill as relief areas called the rake. Moreover the angle of the point varies with the material. The harder the material the less pointed the point. We had to make these things by hand and were graded by an optical comparator. Machineries handbook is a good source of info for stuff like this.
Pointy drills are for wood. Not so pointy are for metal. From: Josh Reynolds Sent: Wednesday, June 03, 2015 6:36 PM To: [email protected] Subject: Re: [AFMUG] Sharpening Drill Bits It's funny to find this discussion on the list today, we have been talking about our drill doctor since this morning. We use a lot of 5/8"x18" Irwin installer bits. We like them because they are reasonably priced, long enough to get through most of the log cabins here, and come with a 90deg angle point as opposed to the more common 118deg angle point. We run them into the ground though, which sucks the next time you have to drill through thinner wood siding or shingles because it will often split the wood on the exit hole, so you have to keep them sharp. We have a drill doctor, but it just does the 118deg angle which doesn't bite as well. Spent part of the day looking for a drill doctor with a 90deg or better angle, but it seems they don't make one. We'd probably be better off buying a table grinding wheel and a drill bit jig, but that can get spendy. Our end result decision is to just buy a crap ton of irwin bits. If anybody has a source for these, we'd like to buy in bulk at cheaper than $11/bit (local pricing). Josh Reynolds CIO, SPITwSPOTS www.spitwspots.comOn 06/03/2015 04:12 PM, Rory Conaway wrote: I bought a drill doctor and even though the bits looked good, they didn�t work as well.� We do mostly wood but installers are sometimes too lazy to change the bit when they get to the stucco and that dulls them faster. � Rory � From: Af [mailto:[email protected]] On Behalf Of Adam Moffett Sent: Wednesday, June 3, 2015 3:50 PM To: [email protected] Subject: Re: [AFMUG] Sharpening Drill Bits � *doing it with a bench grinder. I was at a machine shop where they were doing it with a ben You can do it by hand with a bit of practice. � From: Glen Waldrop Sent: Wednesday, June 03, 2015 4:24 PM To: [email protected] Subject: Re: [AFMUG] Sharpening Drill Bits � My dad has always sharpened his own, so I tend to do the same. In my experience, if used in wood they can be sharpened with little issue. If you drill through metal, buy a new one. � It loses some of the hardness on the edge. It really needs to be tempered again after sharpening. � � ----- Original Message ----- From: Rory Conaway To: [email protected] Sent: Wednesday, June 03, 2015 5:18 PM Subject: [AFMUG] Sharpening Drill Bits � We are paying $15-$25 for longer drill bits.� When they start to get dull, just wondering if anyone has had success sharpening them or do you just buy new ones? � Rory Conaway � Triad Wireless � CEO 4226 S. 37th Street � Phoenix � AZ 85040 602-426-0542 [email protected] www.triadwireless.net � �You may be an engineer if your idea of good interpersonal communication means getting the decimal point in the right place.� � Unknown � � �
