Drill shank repair

C

Clock work

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Greetings.. I have a healthy population of drills with shanks that range from semi-crappy to raped and left for dead. I have never once spun a drill bit (at least in the last 25 years) but "I have friends" and I also have one of those inherited collections of unknown lineage... 100's or maybe more. But many, many with chewed shanks.

I'd like to convert these from scrap into an asset. There are already so many impediments to drilling good round holes that I don't want an ill-considered repair procedure to push things even further into the realm of screwed up and even less precise. I can list the flavors of damage I have but I do believe I have most or all kinds, so any advice is very likely to be pertinent. Does anyone have any thoughts on this matter?

Thank you in advance.

CW
 
woodtickgreg said:
Tool post grinder mounted on a lathe?
Click to expand...
The fact that the shanks are burred up says that they are not hard, and may be cut with a tool; if one has the means at his disposal, grinding 3 flats on the shank like a Silver and Deming drill, especially with the larger sizes is a good thing, that way, they CANNOT spin in the chuck.
 
You can probably save a few by cutting the shanks a bit shorter and filing off the burrs; it's when they are bent that things get interesting
Drills aren't really too expensive in the grand scheme of things- I would chuck the really bad ones (chuck, as in throw out, not Jacobs LOL)
Mark
 
benmychree said:
The fact that the shanks are burred up says that they are not hard, and may be cut with a tool; if one has the means at his disposal, grinding 3 flats on the shank like a Silver and Deming drill, especially with the larger sizes is a good thing, that way, they CANNOT spin in the chuck.
Click to expand...
A spindex on a surface grinder or a tool and cutter grinder would make short work of that, either full diameter or three flats. Issue might be clamping the drills, there are so many sizes. Something could be cobbled together to use with other grinders, even bench grinders, with a little thought. Clamping hundreds of different sizes of drills accurately and quickly is the big issue.
 
if you have access to ER series collets and a ER Hex block
install the drillbit in the ER collet with the shank exposed and mount the drill in a lathe chuck
either grind or file the damaged shank to desired repair.
if the shank is really messed up take a skim cut, but you may introduce some runout.
no matter what you try, you have a chance of altering the concentricity- but that usually is not a big deal when drilling anyway
 
Guys... every single one of these is a GREAT response. Thank you much. I think i'm gravitating to the three flats idea first, which, as the gentlemen noted shifts the clever part to the work-holding and maintaining concentricity. I'm thinking the "good" drills can maybe play a role in this. In fact, I think I have it:) Let me revisit this idea when my eyes aren't closing just to preserve the tiny chance I won't sound extra stupid:)
 
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