MT3 tang issue

[RSG]

I recently bought a new drill chuck for my lathe which came with a tang on the end of the MT3 taper. It causes the tailstock quill to stick out quite far so I was wondering what's the best plan of action.

https://flic.kr/p/XvExpi

https://flic.kr/p/WUBJ5Y

Do I:
A) cut it off
B) Disassemble the tailstock and shorten the threaded quill spindle

Any advice would be appreciated.

[Steggy]

I recently bought a new drill chuck for my lathe which came with a tang on the end of the MT3 taper. It causes the tailstock quill to stick out quite far so I was wondering what's the best plan of action.

https://flic.kr/p/XvExpi

https://flic.kr/p/WUBJ5Y

Do I:
A) cut it off
B) Disassemble the tailstock and shorten the threaded quill spindle

Any advice would be appreciated.

Are you saying the MT3 taper tang is bottoming out in the tailstock and thus you can't fully retract the quill?

[stephenc]

Cut it off ... I've had to cut three or four of them off for my lathe

[John Evans]

But !! Don't cut off too far or it may not eject. {don't ask} Crank out the quill ,install the chuck. Then retract the quill and note the reading on the quill scale where it releases ,use that figgure to tell you how much to remove. I've had non release issues when using adapter sleeves on MT tool shanks ie sleeveing a MT 2 to fit a MT 3 TS. Fun then ensues removing said tooling .

[jcfx]

I'll second what John said about measuring before cutting off the tang.

Another method I use is to make a quick and dirty depth gauge with a shaft collar and a rod,
set your quill to 0 on the scale, insert the rod till it hits the back quill screw, set the shaft collar to
rim of the quill and lock the shaft collar, extend the quill and insert the MT, mark with a fine point sharpie
where it's seated. line up the makeshift depth gauge to the MT and how ever much the tang extends past the
the end of the rod is how much you need to cut/grind off.

[RSG]

Thanks guys,

Why do they even bother adding it. I mean it's obviously there to stop the chuck from spinning but looking at other MT3 tooling I have there is no tang and I haven't ever had an issue with those provided I had the taper inserted properly. I'll prepare to cut it off as indicated above.

[NP317]

If you properly clean the taper and tooling EVERY time before use, there should be no problem with spinning the chuck.
~RN

[Glenn Brooks]

Sometimes the tang is just oversized for the slot in the tailstock. Or actually the tailstock slot is to small and narrow to fit the tang. I recently ground down a tang on a new taper to make it more thin and it then fit nicely.

Glenn

[BadDog]

The tank is for ejection, but ejector or drift. The taper is for holding. The tang also provides some ability to limit rotation, but many lathes don't even capture the tang, and those that do have a lot of slop to suit somewhat arbitrary tang dimensions. So some rotation is generally required to bring it up on the stop, at which point you've already lost the taper's hold (it's not dynamic rather than static) and the tang is unlikely to carry it all on it's own. I don't claim to be an authority, but I know there is quite a debate about the tang's function as a holding element.

I've got tangless live centers and drills with tangs, both work and eject fine in my lathe, which also happens to have the taper capture feature so you can only insert at 180* index. It also has a slot side provision for a drift, though I don't recall having used it. The ram is also marked for length, with a non marked range suitable for zeroing (not that it's useful most of the time) with both tanged and non-tanged tooling. Tanged pop loose a little way into the dead zone, and I just have to crank it further from the measurements termination to eject a live center with no tang. Once it hits the measurements, it still has 5" of marked travel for both.

[RSG]

Thanks for the additional remarks. With the tang in place I loose 1/2" more than without it which maybe is not as big a deal as I think but I am used to starting at the 1" mark on the quill and that's where I am comfortable, that and it gives 4 full inches of travel.

[SteveHGraham]

The graduations on my ram "start" at something like 1/4". By that I mean stuff falls out of the taper if I retract farther.

[BadDog]

I got my head turned all around trying to describe this from memory as I normally don't pay it much attention. But the gist of what I was trying to say was that all the tooling I have for my MT4 lathe tailstock will eject before the scale clears the casting. So trying again after going and checking, and getting my head turned around right...

My ts quil goes a full inch past the marking into the casting before it bottoms almost flush. It ejects just a little past zero, maybe 1/8" from the markings with a big MT4 taper with tang, more with smaller drills/tangs. That's with almost an inch still outside the casting, and no scale showing. With a tangless live center, it ejects something like 5/8-3/4" from the markings. It varies because my taperless tooling (generally live centers) have non-taper extensions behind the taper, so where it hits the ejector pin varies. I think the shortest I have is a concentric spring loaded MT4, and it will eject normally.

So it appears my lathe was made to provide the rated full travel for even large taper long tang tooling, and also still eject with short/no tang before bottoming, and even the largest taper will seat with a bit of range before it starts the scale markings. So at a minimum I have the marked 5" travel, and pick up approaching another inch with a truncated taper. And with the drift option, unless I really stub off a center, not ejecting before the screw bottoms isn't a huge issue, though I've never used it.