atlas tail stock

Although Stephen A. Morse invented the Morse taper as a means of driving his newly patented twist drills, there was no attribution of the taper in a patent search under his name. He did send a master standard to the National Bureau of Standards where is was accepted as a standard. There have been numerous references to the tang as an anti-rotation device in the literature that I have reviewed , but no reference to a patent. A shame because that would unequivocally answer the question.

A final thought. Why go to the bother of broaching a socket for the tang if not to prevent rotation?
 
RJSakowski said:
If the tang was designed for ejecting the taper and not as an anti-rotation device, why would it have two flats? You could eject it with just a reduced diameter stub on the end.
Click to expand...

The tang is so that when you use a sleeve and drive the separating feather /key in to the sleeve to separate the drill you don't mushroom the softer dead end of the drill & cause it to jam in the sleeve .
Remember , morse tapers are a system of using friction at /in precision faces to drive the drill , they are not specific to one model of lathe .
So an 8 mm MT2 could be sleeved up to fit into an MT4 or MT5.

Thinking about it a bit more & still thinking about what I've already said perhaps by only taking the taper so far down and then making the slot for the feather at the end of it just happens that the tang goes into the slot area as the slot may well be at the end of the length /depth of the taper quite by accident rather than by design .
I've not found any tangs that fit snugly in the taper at 90 degrees to the feather slot they all stop well before that and you have to rotate the drill to get it to go in any further.
Could this be because the feather slot has been hot punched in the blank sleeve to make broaching /milling it out easier ?

I do however had a couple of morse taper drills that came with the lathe that have been badly ground or turned down on the tang end .
I assumed it was done because of the mushrooming of the tang happening when being brayed out using the wrong face of the feather or an incorrect sort of feather such as one made from ground down tool steel . or When someone has walloped the drill in a slipping/ scored /burred /dirty taper to make it hold and then couldn't easily get it undone again .
 
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Round in circles said:
The tang is so that when you use a sleeve and drive the separating feather /key in to the sleeve to separate the drill you don't mushroom the softer dead end of the drill & cause it to jam in the sleeve .
Click to expand...
A reduced diameter stub would work as well for that and be easier to make.
 
Round in circles said:
The tang is so that when you use a sleeve and drive the separating feather /key in to the sleeve to separate the drill you don't mushroom the softer dead end of the drill & cause it to jam in the sleeve .
Remember , morse tapers are a system of using friction at /in precision faces to drive the drill , they are not specific to one model of lathe .
So an 8 mm MT2 could be sleeved up to fit into an MT4 or MT5
Click to expand...
Ah, but you don't need a tang with flat sides and corresponding broached socket to be able to drive the the taper out. A reduced diameter cylindrical sleeve would work as well. Even if you have the tang as it exists currently, you wouldn't need a broached socket to mate. A cylindrical; bore will work.

The hypothesis that I presenting is that the flat sided tang would have been designed with a purpose. It would cost more to make the taper as designed which would not be good engineering practice unless it was also intended to be an anti-rotation mechanism.

(John, your post came through as I was typing, so please excuse the redundancy)
 
RJSakowski said:
The hypothesis that I presenting is that the flat sided tang would have been designed with a purpose.
Click to expand...
The tang does have a purpose, that is to assist in removal. It is the taper(self locking) that is designed to provide sufficient friction with which to drive the drill.
If tapers slip it means they are dirty/damaged, and if being driven as they were designed to be, any slippage would result in a sheared tang. Under light load they may slip and catch and appear to have sustained no damage, but i can say from experience that even this can fail. Long story short, if you rely on the tang as an anti rotation device, eventually you will lose a tang.
Grind/turn a tang down, see how long the stub lasts before it mashrooms/bends/breaks.
Make some sleeves as you describe them, let me know how that goes. i.e. trying to separate.
Do a bit of research on levers/wedges first, and have a closer look at a drawing of a morse taper
to see how and why they are made the way they are.
Did my time, broke plenty of drills along the way. Thats life.
 
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Further research through my copy of "Fitting and Machining" (Ron Culley), a text from TAFE studies prior to starting apprenticeship, iv'e found another direct reference.
"Taper shank drills are driven by the taper and not the tang. The tang is designed for ejection not driving.It is essential that the drill shank and socket are a good fit and free of burrs and grit, otherwise slippage will twist the tang."
Not trying to be a wa**er, passing on some information. It is very common, this misconception about taper shank drills.
 
I understand the principle of a locking taper. I have designed devices with locking tapers in the past. I have also used Morse tapers for more than forty years. I also understand the use of a drift to unseat a Morse taper.

My original question was why are there flats on the tang?
 
BTW, Over the years, I have collected a number of straight shank drill bits that have tangs with flats. Here is an example.
Besly
Jobbers Length
Tanged
Twist Drills

High Speed Steel
Straight Shank

Wire Gage,
Letter and
Fractional Sizes
Catalog Number: T-105-T
drl12b.jpg

These surface treated automotive series drills are of the same design and general dimensions as Catl No. T-105 except for the addition of a tang to fit drill holders for the purpose of driving the drill.
 
Due to the way the sleeve/socket/spindles are made. To reach up the slot to where the drift will be when used for removal. Note that the tang has a considerable amount of clearance in all directions.
Straight shank drills wont fit a morse taper, different kettle of fish altogether.
 
RJ (please set up your Signature or sign your posts).

Unless someone turns up an old textbook with a proper bibliography referencing someone's patent, I don't think that you are going to get anything but everyone's opinion. Of the textbooks that just state a reason without attribution, most seem to go with for removal.

My personal opinion is that it must be for extraction from drill press spindles. This is based upon experience using taper shank drill bits or arbors with tangs in drill presses. If the taper comes loose, the tang will continue to drive it but it won't turn true and will drop out noisily as soon as you raise the quill. So under that circumstance the tang's turning ability makes things worse, not better.
 
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