Newbie question about morse tapers

S

sacentre

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Just wondering, why do so many morse taper arbors (not all) have a small parallel shoulder on the small end? Does it serve any purpose? I see this on arbors with and without a draw-bar thread.

TIA

Screenshot 2023-09-28 124553.png
 
Some tailstocks press out the taper (when one fully retracts the quill, a pin on the
quill drive screw makes contact); those might deform the tapered surface
if there weren't a bit of noncritical metal forming a
button for them to apply force to.

I've got a tailstock that broke its pin, and stopped forcing out the
taper, that will have to be fixed soon...
 
Drill press spindles designed to use Morse taper tooling have a slot where a wedge/drift can be inserted and pounded home to free the drill bit or the arbor. See photo below. Lathes generally do not have the slot so the tang's only purpose would be to pop the Morse taper loose when the tailstock spindle is retracted.

16585c7b9f6414532250276183a09ba9435f2461.png
 
Some lathe tailstocks have a slot for a drift to eject tight tooling where rotating the tailstock handwheel is not enough to eject them.
 
Parlo said:
Some lathe tailstocks have a slot for a drift to eject tight tooling where rotating the tailstock handwheel is not enough to eject them.
Click to expand...
For one, the American Pacemaker lathes have a tang slot in the tailstock spindle.
 
Most of the centers I have do not have a tang, but chuck arbors do, especially in the larger MT sizes (MT3+). Possibly to drive more torque of the drill vs. a center that’s essentially just sitting there. Agree that the flat area at the end may be for not mushrooming the end, but may be a manufacturing convenience so the grinding wheel can come off the ground surface without hitting whatever is driving the shaft or holding center.
 
I think the centres don't have a tang because they won't be used in anything other than a tailstock which has an ejection pin.
 
In the case of the lathe, I add a tang to my tang-less centers so that I may eject them by reeling my tailstock to the rear, avoiding the use of the wedge.

GsT
 
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