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Old 08-09-2019, 08:50 AM
Shade Tree Welder's Avatar
Shade Tree Welder Shade Tree Welder is offline
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Default MT3 issue with short or no tangs on live center.

Quote:
Originally Posted by Shade Tree Welder
In reference to my Lathe tail stock that has a MT3
socket.

So my drills and drill chuck arbors all have a tang that
extends to the slot in the tail stock spindle. So you can
use the correct drift and loosen the drill or chuck and
remove it. However neither of my live centers have a
tank and do not extend to slot they stop just short.

What is the correct method of removing them?
Quote:
Ron,

That type of short shank tapers are always a problem. I don't know why they make them that way.

Some have a female thread on the end--they're pretty easy to deal with. Just thread in a stud or setscrew that sticks out a bit and you're good to go.

I have seen guys grind the slot on the tailstock--or whatever machine you're dealing with. A little time with a die grinder is usually all it takes to open the slot up enough that your drift key will work--you only have to move the taper a few thou to break it loose.

You can also take a drift key and grind it like I've shown in the attached drawing. Grind a small bump on the end at the point just before the key is tight in the slot. A little relief beside the bump allows you to place the key in the slot and give it a good sharp rap with a hammer. The key pivots against the slot in the tailstock and bingo, the taper pops out...

Hmmm......just found out I can't attach a picture to a PM. If you want you can send me your email address and I'll send you the sketch I drew up. Or I can post the whole message in the machining section. Your call...
I am glad I was not me being just stupid.
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Old 08-09-2019, 09:12 AM
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Here's a pic of what I was describing...
Attached Files
File Type: pdf Drift Key Modification.pdf (2.4 KB, 56 views)
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Old 08-09-2019, 10:13 AM
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I have a live center with no tang that would not eject the first time I used it.
My tailstock ejects most things by retracting it into the barrel just past the zero mark on the quill. I just shoved a 1/4 nut into the key slot and it ejected as it should.
Then I made a new end for the center that was long enough to eject.
I have some smaller drills that require a reducer to fit into the tailstock. it is a pita to separate them so I can use the adapter with a different drill.
I have a pickle fork type separator but sometimes there is just not enough space between the adapter and the bit to use it.
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Old 08-09-2019, 10:26 AM
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On some of mine the end was threaded so I made a extension and threaded it on others I have actually welded a extension on.
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Old 08-09-2019, 11:05 AM
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Quote:
Originally Posted by digr View Post
On some of mine the end was threaded so I made a extension and threaded it on others I have actually welded a extension on.
That was my thoughts.

I asked Keith as I though I might have been missing something obvious.
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Old 08-09-2019, 12:15 PM
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Quote:
Originally Posted by Shade Tree Welder View Post
...as I though I might have been missing something obvious...
Yeah there's certainly no obvious fix for the problem. As I said before I have no idea why they even make the MT shanks with the short ends. In most situations it would only take another 1/8" of length (or less) to make sure that a drift key or the automatic ejector in the spindle would spit out the taper. Lots of different ways to deal with the situation but they're all kind of an improvisation rather than a proper fix...
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Old 08-09-2019, 07:38 PM
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Quote:
Originally Posted by LKeithR View Post
Yeah there's certainly no obvious fix for the problem. As I said before I have no idea why they even make the MT shanks with the short ends. In most situations it would only take another 1/8" of length (or less) to make sure that a drift key or the automatic ejector in the spindle would spit out the taper. Lots of different ways to deal with the situation but they're all kind of an improvisation rather than a proper fix...


Some well placed welds will add a tang on, and can grind back down if needed. I have been doing that on a couple drills and adaptors lately at work, because someone in the past have ground the tangs off or down.


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Old 08-10-2019, 08:44 AM
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Quote:
Originally Posted by LKeithR View Post
Yeah there's certainly no obvious fix for the problem. As I said before I have no idea why they even make the MT shanks with the short ends. In most situations it would only take another 1/8" of length (or less) to make sure that a drift key or the automatic ejector in the spindle would spit out the taper. Lots of different ways to deal with the situation but they're all kind of an improvisation rather than a proper fix...
I've never seen one that was short and not threaded. I always thought they were made that way so a drawbar could be used as in a lathe or mill with MT needs.
I have some, everyone does, and I just screw in a bolt to the right length and loktite it in place.
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Old 08-10-2019, 06:33 PM
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"MT3 issue with short or no tangs on live center ?"

Are you talking about, a tang that would prevent the center or a grill chuck from spinning, in the tails stock, under load?

If yeas, there is no reason for a tang or slot for a tang. The taper creates an interference that hold things in place. It the force or load on the work causes the tool to spin. That saves the tool, keeps thing from breaking.

To remove just turn the hand wheel on the tail stock full back the chuck or center dead or live to fall out.

Pep
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Old 08-11-2019, 12:39 AM
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Quote:
Originally Posted by pepi View Post
....If yeas, there is no reason for a tang or slot for a tang. The taper creates an interference that hold things in place. It the force or load on the work causes the tool to spin. That saves the tool, keeps thing from breaking...
I've seen lots of drills with the tang broken off. A bigger drill and too much power is all it takes. If you spin the drill in the taper then you run the risk of damaging it. I'd rather keep my tailstock or drill spindle unmarked.

Quote:
...To remove just turn the hand wheel on the tail stock full back the chuck or center dead or live to fall out...
That works on some tools but not all of them...
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