Morse Taper Slipping between Drill Chuck and Tailstock

[erikmannie]

I was discussing this issue in an MT3 drill thread, but I don’t want to hijack that thread.

I have a PM1030V with an MT2 tailstock, and I believe that it does not have a female slot for a tang.

I bought an inexpensive 3/4” JT33 to MT2 drill chuck. From the very beginning, I suspected that the manufacturer was not entirely successful in obtaining a proper male MT2 taper. I get problems with slipping at the MT2 interface.

I may solve this problem by buying the 250-105 pictured below. The slot for the tang would prevent any rotation at the MT2 interface, but my drill chuck also has a JT33 interface which hasn’t slipped so far.

I almost always work with steel, and it is entirely possible that I will be using drills up to 1”. I wonder if that would go smoothly with the MT2 tool post holder pictured below on a 10” swing, 1 HP lathe.

 

[erikmannie]

Methods I use to prevent slippage:
(1) wipe off male Morse taper before inserting in to tailstock,
(2) always start with center drill, very conservative step drilling,
(3) always use cutting fuid,
(4) not getting greedy with cutting (patience),
(5) proper RPM,
(6) peck drilling, and
(7) frequently clearing out chips from drill and hole (I use a magnet probe).

 

[gradient]

You could check for proper mating between the male and female MT2 by coating the male part with mark up dye or magic marker and mate them in the usual way. Remove the male part and see if the dye has been removed uniformly. You may also need to lightly mate them and rotate them a bit.

 

[erikmannie]

Before I got a lathe and mill, I used to have terrible problems drilling steel with a hand drill and drill press.

When I got a job at a steel fabrication shop, my first question to the boss was tips on drilling in steel. He said “go slowly and use plenty of lubricant.”

 

[erikmannie]

You could check for proper mating between the male and female MT2 by coating the male part with mark up dye or magic marker and mate them in the usual way. Remove the male part and see if the dye has been removed uniformly. You may also need to lightly mate them and rotate them a bit.

I will do the dye check.

I do like to seat it by hand with a pushing rotation, but I am a little perplexed by the tang.

The male MT2 arbor will rotate in the tailstock, so I am inclined to believe that there is no female slot for a tang. So why do I even bother to align the tang vertically when I install the arbor?

I do find the tang useful for ejection, but I wonder if I should just cut off the tang. It costs me just under an inch of quill travel.

Maybe I should buy a JT33 to MT2 arbor with no tang. The MT2 fit up couldn’t possibly be any worse.

But wouldn’t buying the AXA MT2 tool holder take the tailstock out of the equation, and then I would be good?

 

[erikmannie]

I did buy the 250-105 AXA #2 MT tool post holder for $30. I will let you guys know how it works out. Hopefully the JT33 interface doesn’t slip.

It seems to me that there would be an upper limit on the diameter of drills that can be safely used for drilling steel (either in a tailstock or on a toolpost) in this smaller sized lathe.

Worst case scenario, a huge drill mounted in the toolpost crashes into the work. What is the weak link there?

When I crash a cutting tool, the motor stalls and I either back off or hit the e-stop. I wonder if that situation would damage my compound or cross slide if a huge drill were mounted in the toolpost. Maybe the JT33 interface would be the weak link and slip at that point.

 

[pdentrem]

I would be feeding by hand incase of that possibility and having to back off to add cutting oil. I would likely NOT use the power feed on large diameter drills. Others may do so but not me.
Pierre

 

[Aukai]

Make sure the quill is far enough out that the arbor seats without the tang hitting the back of the quill. Mine has to be out 1" for the tang to clear, and get a good seat.

 

[T Bredehoft]

The tang was never meant to be a driving device, it is solely for removing the drill from a spindle, (see drill
press and slot in spindle)

 

[ErichKeane]

I will do the dye check.

I do like to seat it by hand with a pushing rotation, but I am a little perplexed by the tang.

The male MT2 arbor will rotate in the tailstock, so I am inclined to believe that there is no female slot for a tang. So why do I even bother to align the tang vertically when I install the arbor?

I do find the tang useful for ejection, but I wonder if I should just cut off the tang. It costs me just under an inch of quill travel.

Maybe I should buy a JT33 to MT2 arbor with no tang. The MT2 fit up couldn’t possibly be any worse.

But wouldn’t buying the AXA MT2 tool holder take the tailstock out of the equation, and then I would be good?

So, you NEED the tang to get the tool out of the tailstock. However, they are typically quite long. I've been considering machining mine down to the bare minimum. It simply needs to be just barely long enough to touch the back when retracted all the way. If you retract it to JUST before it pops out and measure how much more the tailstock can retract, you'll know how much material you can take out!