atlas tail stock

A simple reduced Dia. on the end of the taper with a matching female hole in the bore would have been easyer and cheaper to make.
Yes they would still have to mill a slot in the spindle for removal, on drill presses and such,not tailstocks, but tooling would be easyer to produce.
The tang gives a bit of added holding ability while pressure against the work helps re-seat the taper.
In job shops, there's always those who don't clean the tooling or the bore and the taper cant fully hold due to oil or dirt.
The tang helped prevent tool rotation then and still works now.
 
In the course of many years I have seen tapered shank drills turned undersized at
the end- probably shop made........JHBLAG.
 
Tom
I don't mean to imply the taper shank drive's the bit. That would clearly fail and we all know the taper should hold firmly.
Only mean that the shank can help a little if the bit slips in the fit, at least giving the taper a chance to better grip.
 
If you look at the very end (face) of the tang, you will see that they are not flat, straight across perpendicular to the axis of the tool. This can be a large radius or two angles. This is done to match the angle of the drift key used to remove them. A round stub in the middle could have a bevel, but at the max diameter that would fit where the tang does, it wouldn't function as well as the end of the tang as they are designed.
 
My 13" small spindle south bend, circa 40-50 (guess) does not have a tang holder.

As long as your tapers are clean and for the most part undamaged, you shouldn't have a problem with spinning as long as you are feeding in with the tailstock. Self holding tapers (No drawbar, coller nut, etc) are not very strong without axial clamping force and like to come out.
 
If the tang was just used just to eject it they would or could just be a round pin but instead they made it fit into a nice pocket a lot of work for just an ejection pin. At any rate mine does not spin anymore and ruining the taper all it takes is one spin and the taper is done. It worked so well I made a new barrel with a pocket inside for the tang.. I would not have it any other way now.. do as you will..Ray..

And according to this there are several different drills with a drive tang.

http://www.mfg.mtu.edu/marc/primers/drilling/nomen.html

http://www.amesweb.info/Tooling/TaperShankTwistDrills.aspx
 
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This thing about the tang on the drill and attachments has puzzled me for a few days as none of the explanations seemed 100% watertight in thought and deed .

Today I picked up a 1 & 1/4 inch morse taper drill, suddenly it dawned on me that most of us were / are part right and part wrong.

I now strongly feel that the tang is ground on the blank along with the center point hole at both ends most likely as the first operation in making the drill .
So that the drill/sleeve or mandrel blank can be held in a device similar to being driven between centres and driven by a dog that the tang locates in/onto so it can be ground between centres on a special multi tooled machine . Once the taper is accurately ground on the drill the mandrel end can now be accurately /securely held for the flutes to be ground on the drill & for it to be machine sharpened .

Yes the tang is also ground up for extraction & clearance purposes as well

The more I looked at the drills , the tang , the centre point in the tang and the sleeves etc it became hard to think why none of us had though of it before .
Can anyone now say otherwise with a greater level of reasoning . ?
 
Nope. Your analysis is quite logical. You may well have hit the nail on the head. Although I have seen (and have at least two of) arbors without the tang, I can't ever recall seeing a taper shank drill bit without it.
 
More unnecessary advice: why is there a " scar " in your taper socket ? someone
didn't ( very carefully ) clean the sexy parts before mating.
 
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