Educate me on MT2

[HalcyonDaze]

I'm not sure if this is the right forum, but it pertains to an Atlas milling machine, so why not?

The spindle on my mill is a MT2, as you all probably know. I'm going to build a vertical head and have decided to just buy a lathe spindle instead of making a spindle. I got a spindle from an Atlas 12" which has a MT2 taper (I was told by the seller). I specifically wanted the same taper in both spindles so that tooling could be interchanged. Problem is, the bore in the mill is smaller than the bore in the lathe, in other words a collet that fits correctly in the mill spindle falls way down inside the lathe spindle. Since they are both MT2, I thought that the bores would be the same.

So educate me about tapers. I thought (probably incorrectly) that all Morris tapers were the same angle, and the number was the size of the bore (i.e. MT2 is a different size than a MT3, with the same angle of taper in both).

Where is my thinking flawed?

 

[Ray C]

The angles are different for the various MT sizes. Within each type there are "standards" for short and long versions. Long versions usually have a tang on the end. This mainly impacts the female socket dimensions. In all reality, I've seen MT in a given size vary their nominal/base diameters a good bit.


Ray

EDIT, if you measure the small diameter and as best you can, the large diameter as well as the distance between the points you measured from, I might be able to tell you what you have. The problem is measuring the large diameter as there is no distinct lip to measure from. BTW, the differences in angles is very, very small -but it makes a difference...

I'm not sure if this is the right forum, but it pertains to an Atlas milling machine, so why not?

The spindle on my mill is a MT2, as you all probably know. I'm going to build a vertical head and have decided to just buy a lathe spindle instead of making a spindle. I got a spindle from an Atlas 12" which has a MT2 taper (I was told by the seller). I specifically wanted the same taper in both spindles so that tooling could be interchanged. Problem is, the bore in the mill is smaller than the bore in the lathe, in other words a collet that fits correctly in the mill spindle falls way down inside the lathe spindle. Since they are both MT2, I thought that the bores would be the same.

So educate me about tapers. I thought (probably incorrectly) that all Morris tapers were the same angle, and the number was the size of the bore (i.e. MT2 is a different size than a MT3, with the same angle of taper in both).

Where is my thinking flawed?

 

[HalcyonDaze]

I'm with ya so far.

Now, the bore opening on the mill spindle (large end) measures just under 3/4", while the bore opening on the bought lathe spindle measures just under 7/8". My collet set fits the mill spindle just right, but they fall down inside the lathe spindle. How would I order collets for the larger bore?

Bear in mind that I've been told by the seller (ebay) that the bore on the lathe spindle is MT2. It's from a 10" or 12" Atlas with Timken bearings with a 1 1/2x8TPI threaded nose, if that helps to identify. I'm wondering if it is a different taper than what I've been told, which would explain the collet dilemma.

 

[Ray C]

The Tailstock on most Atlas machines is MT2. The spindle taper is something else -which escapes me at the moment. I'm sure someone here knows the spindle taper for an Atlas. I think it's something similar to a 3C.


Ray

 

[HalcyonDaze]

That confirms my suspicion that it was other than MT2. Maybe I should have started by researching that lathe bore. Thanks for the help, Ray.

 

[Hawkeye]

Southbend and Hercus lathes have MT2 tailstocks and MT3 spindles, so I'm thinking that's what you have.

 

[awander]

I've just spent 45 minutes looking for data on the bore taper of the Atlas 12" lathes, and the exact answer has so far eluded me.

According to the 1952 catalog from this site's downloads section, the 10" lathes are "bored for 3 Morse Taper, with reducing sleeve for 2 Morse Taper.

Lathes.co.uk says that the Atlas lathes in 10" size " held a 3 Morse taper centre", so I find it hard to believe that they would have made 12" lathes with a smaller headstock taper.


And just to add to the other info you have been given, a 2MT collet that properly fits your 2MT mill spindle should not fall "way down" inside any other 2MT spindle.

BTW, it is "Morse" taper, NOT "Morris" taper.

Edit:

I just found Atlas Catalog 300 for the 12-36 lathe, and it states 3MT internal spindle taper.

 

[aforsman]

I just unscrewed the chuck on my 10" Atlas and stuck a MT3 dead center in the spindle bore - fits perfectly.

 

[genec]

you can buy a mt3 to mt2 adaptor should solve your problem

 

[HalcyonDaze]

According to the 1952 catalog from this site's downloads section, the 10" lathes are "bored for 3 Morse Taper, with reducing sleeve for 2 Morse Taper.

Lathes.co.uk says that the Atlas lathes in 10" size " held a 3 Morse taper centre", so I find it hard to believe that they would have made 12" lathes with a smaller headstock taper.

And just to add to the other info you have been given, a 2MT collet that properly fits your 2MT mill spindle should not fall "way down" inside any other 2MT spindle.

Edit:

I just found Atlas Catalog 300 for the 12-36 lathe, and it states 3MT internal spindle taper.

Thanks for spending time on this, saved me some work. BTW, the collet fit the mill spindle properly but fell deeply into the lathe spindle of unknown taper.

I just unscrewed the chuck on my 10" Atlas and stuck a MT3 dead center in the spindle bore - fits perfectly.

That's the kind of confirmation a man can believe in! Thanks.

you can buy a mt3 to mt2 adaptor should solve your problem

Probably what I'll do, to keep things simple.