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Old 06-24-2007, 02:53 PM
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Default Why would you grind a drill "flat"

Any particular reason one would grind the end of a drill flat like a end mill? Nope they are not broken...I have a few in my bucket of delights that are like that.
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Old 06-24-2007, 02:58 PM
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they are just really worn out. or maybe some one wanted the bottom of a blind hole flat/square.
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Old 06-24-2007, 03:33 PM
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If you need to counter bore a hole for a S.H.C.S. Allen bolt.
A flat bottom drill works good after you have pre-drilled the hole with a standard pointed drill.

BTW. did you know that end mills are not flat.
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Old 06-24-2007, 05:41 PM
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yes I knew that It very possible it was used as a counterbore...Unless the piece is locked down real secure I dont see it working that well without the locating hub of a real counter bore? For the price I think I would just buy a counterbore set and have it be right

I will have to find the bits in question and see if they are the correct clearance for a socket head
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Old 06-24-2007, 07:15 PM
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If you grind a bit flat with a small point in the center (a centering guide, no real cutting action) they work great for cutting spot welds on sheet metal.
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Old 06-24-2007, 07:34 PM
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Quote:
they are just really worn out.
Snort, giggle, hysterical laughter. Good one Randy.

If you look at or can be privey too an industrial setting that re-grinds certain drill bits, you will see them at times, grinding the cutting ends square and flat across it's length.

This will be most often done when the drill bit was in use and has broken with way too much of it's cutting end to not allowing a simple re-sharpening or tipping as some will call it.

Once the bit is ground flat/square, then the process of grinding quality cutting edges that is near perfect/centered and very close to absolute true.
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Old 06-24-2007, 10:36 PM
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Quote:
Originally Posted by lwhiway View Post
Snort, giggle, hysterical laughter. Good one Randy.

If you look at or can be privey too an industrial setting that re-grinds certain drill bits, you will see them at times, grinding the cutting ends square and flat across it's length.

This will be most often done when the drill bit was in use and has broken with way too much of it's cutting end to not allowing a simple re-sharpening or tipping as some will call it.

Once the bit is ground flat/square, then the process of grinding quality cutting edges that is near perfect/centered and very close to absolute true.
Oh it was that simple.
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Old 06-24-2007, 11:40 PM
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Quote:
they are just really worn out.
Heck yes that was funny. lol

I have to share this. When I first started here in Lake Charles, it was still owned by Grumman, pre-Northrop buy out. I was then working in/with the Quality Assurance division, mapping wing planks and their involved fasteners, steel and aluminum.

While sitting on top of a wing, answering a call on the call sheet, I hear this hellashish squealing howling, much like the sound a coyote would make if you were pulling his teeth out one at a time with a pair of vice grip pliers and pouring acid on his hind end at the same time. Got a graphic of the noise now?

I swing around on my butt, in time to see a mechanic sitting cross leg'd, pushing down on a drill motor and drill bit trying to remove a steel fastener. What I see, I can't believe. There is a reddish yellow glow at the end of the carbide drill bit, with sparks shooting out in a smallish cone there as well and smoking all to be darn. Boe-lube does that with lots of heat.

He's moving this drill motor around in circles while keeping the bit centered on top of this rather large diameter steel hi-lock. We make him stop and I swear to goodness, he's got this look on his face that says, "What, I know what I'm doing". lol

He was moved to another part of the plane where he would be less likely to do any damage.

The "rest of the story" is that he stopped the drill motor, letting it cool a little while the bit was in contact with the hi-lock, and yes friction welded the bit to the fastener.
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Old 06-24-2007, 11:46 PM
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Maybe he wasn't trying to remove the fastener, maybe he was trying to lengthen it. :evil:
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  #10  
Old 06-25-2007, 03:09 PM
TONYL TONYL is offline
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could be a core drill, used for opening up existing holes. they should have a lead-in chamfer on the end.
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