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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Drill bit tolerances
What is the expected tolerance of drill bits? I have a set of fractional,
letter and number drills. No.12 to 15 (including 3/16") seem to produce the same size hole. -- Michael Koblic Campbell River, BC |
#2
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Drill bit tolerances
mattathayde had written this in response to
http://rittercnc.com/metalworking/Dr...es-201627-.htm : ------------------------------------- Michael Koblic wrote: What is the expected tolerance of drill bits? I have a set of fractional, letter and number drills. No.12 to 15 (including 3/16") seem to produce the same size hole. what are you measuring with, 12-15 range .18-.189, also do you have runout on your press, how fresh are the bits, etc. your dealing with such small differences that it will be very hard to get a good read unless you have very high quality measuring devices. -matt ##-----------------------------------------------## Delivered via http://www.rittercnc.com/ Metalworking Forums Web and RSS access to your favorite newsgroup - rec.crafts.metalworking - 175567 messages and counting! ##-----------------------------------------------## |
#3
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Drill bit tolerances
mattathayde wrote:
mattathayde had written this in response to http://rittercnc.com/metalworking/Dr...es-201627-.htm : ------------------------------------- Michael Koblic wrote: What is the expected tolerance of drill bits? I have a set of fractional, letter and number drills. No.12 to 15 (including 3/16") seem to produce the same size hole. what are you measuring with, 12-15 range .18-.189, also do you have runout on your press, how fresh are the bits, etc. your dealing with such small differences that it will be very hard to get a good read unless you have very high quality measuring devices. -matt ##-----------------------------------------------## Delivered via http://www.rittercnc.com/ Metalworking Forums Web and RSS access to your favorite newsgroup - rec.crafts.metalworking - 175567 messages and counting! ##-----------------------------------------------## Any bit not sharpened properly--especially one with the point not centered will drill oversize.. |
#4
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Drill bit tolerances
On Oct 3, 2:17*am, "Michael Koblic" wrote:
What is the expected tolerance of drill bits? I have a set of fractional, letter and number drills. No.12 to 15 (including 3/16") seem to produce the same size hole. -- Michael Koblic Campbell River, BC Have you measured the diameter of the drill bits? I could not find tolerances on drill sizes, but drill blanks are the nominal size plus nothing minus .0003 inches for blanks up to half inch. I would expect drills to have about the same tolerances. Dan |
#6
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Drill bit tolerances
On Fri, 02 Oct 2009 20:41:04 -0700, dcaster@krl... wrote:
On Oct 3, 2:17Â*am, "Michael Koblic" wrote: What is the expected tolerance of drill bits? I have a set of fractional, letter and number drills. No.12 to 15 (including 3/16") seem to produce the same size hole. .... Have you measured the diameter of the drill bits? I could not find tolerances on drill sizes, but drill blanks are the nominal size plus nothing minus .0003 inches for blanks up to half inch. I would expect drills to have about the same tolerances. Also, are you using a mill-drill, a drill-press, or a hand-held drill motor? And what is the material being drilled, ie, wood, aluminum, steel? Clamped or hand-held? If using a drill press or better and drilling into steel or aluminum, I would regard it as an unusual problem -- with the press, the bit, the material, or the work-holding -- if I drilled a hole with a #13 bit (0.1850") and was then able to push a #12 bit (0.1890") through the hole without cutting at least a little more metal. -- jiw |
#7
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Drill bit tolerances
On Oct 2, 6:17*pm, "Michael Koblic" wrote:
What is the expected tolerance of drill bits? I have a set of fractional, letter and number drills. No.12 to 15 (including 3/16") seem to produce the same size hole. I've used the shank of drill bits as gages; they measure within .001" of the marked size. As for the holes, the #12 makes a hole bigger than #13 and smaller than #11 (i.e. look at the gap between sizes), unless it's dirty/bent/dull. Fractional drills, some of 'em, have been off by .005" recently, but they might have been made-for-WallyWorld. People who need real precision don't use twist drills, of course, for the final dimensions. |
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