# Educate me on MT2



## HalcyonDaze (Sep 29, 2013)

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?


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## Ray C (Sep 29, 2013)

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...





HalcyonDaze said:


> 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.
> 
> ...


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## HalcyonDaze (Sep 29, 2013)

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.


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## Ray C (Sep 29, 2013)

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


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## HalcyonDaze (Sep 29, 2013)

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.


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## Hawkeye (Sep 29, 2013)

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


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## awander (Sep 29, 2013)

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.


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## aforsman (Sep 29, 2013)

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


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## genec (Sep 29, 2013)

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


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## HalcyonDaze (Sep 30, 2013)

awander said:


> 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.
> 
> ...



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.



aforsman said:


> 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.



genec said:


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



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


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## PurpLev (Sep 30, 2013)

+1 on the spindle type - usually on those lathes the tailstock will be MT2, but the headstock spindle will be MT3. and as mentioned, there are MT3-to-MT2 adaptors which would be your best bet, or get a MT2 mill spindle and keep it simple (I know you already bought the lathe spindle, so may or may not be in your budget/plan, but that's another option).


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## Uncle Buck (Sep 30, 2013)

genec said:


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



Keep in mind there will be a downside to using a 3 to 2MT adapter. The use of that adapter will cost you a small amount of verticle room. With the Atlas mill, the work window beneath tooling is so very limited even under the very best circumstances that keeping that distance in mind with everything pertaining to vertical head planning and implementation is just so important. If you can figure out a way to get your vertical head higher than the overarm shaft hole it will work to your benefit in the end. 

Also, another consideration, unless you have the original vise that came with your machine you might consider a "LOW" profile vise such as a Palmgren "Lowboy" to be a must have item as part of the strategy to buy some extra work room for your machine. The Lowboy is not cheap these days, plan on over $200 to get the advantage of a low profile swivel base vise for your machine.

My whole point is, be very dialed into preserving as much of your limited working window as you can  any machine modifications. It would be a real stinker to make a bunch of mods and spend a bunch of money on mods to only find out when it is time to make chips that you really have no room to work on anything becuse you have no room to!


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## HalcyonDaze (Sep 30, 2013)

Uncle Buck:  Your vertical milling head is one of the inspirations for what I'm doing.  I've got a Marvin head but don't like it.  I'm going to make a pattern for casting a head that this lathe spindle will fit into and build what will look a little like a Bridgeport head.   Your points about clearance and adapter issues are highly valued and will be factored in.  

It's really no problem to get a set of MT3 collets if that will give more clearance.  I've got the original vise, so I'll be working with that.


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## cjtoombs (Sep 30, 2013)

I belive the Atlas 6" lathes used an MT2 spindle, which is what the milling machine spindle is modeled after.


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## HalcyonDaze (Sep 30, 2013)

There was a 6" lathe spindle selling at the same time and the ad said it had a MT2.  Almost bought it (wish I had now), but the seller of the 12" said he thought his was also a MT2.  The spindle is really big, the 6" spindle would have been better sized accordingly for the mill but this one will work too.


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## Uncle Buck (Sep 30, 2013)

HalcyonDaze said:


> Uncle Buck:  Your vertical milling head is one of the inspirations for what I'm doing.  I've got a Marvin head but don't like it.  I'm going to make a pattern for casting a head that this lathe spindle will fit into and build what will look a little like a Bridgeport head.   Your points about clearance and adapter issues are highly valued and will be factored in.
> 
> It's really no problem to get a set of MT3 collets if that will give more clearance.  I've got the original vise, so I'll be working with that.




Look at the picture of my mill and attachnment. If you have the skills to cast and pour a casting for a head then you should not have an issue. simply design the head you are going to cast so that it has more clearance than what the Marvin head gives you and the #3 MT should not be an issue because you should have a bit of excess room to play with. With the ability to engineer in a bit of additional room the #3 MT will no longer be an issue and using a redcer sleeve should work just fine with the additional room that you have to spare. My point is simply engineer your casting around the issue.


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## calstar (Sep 30, 2013)

Uncle Buck said:


> Look at the picture of my mill and attachnment.



like to see it but no link or image.  Brian


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## Uncle Buck (Sep 30, 2013)

calstar said:


> like to see it but no link or image.  Brian




Here ya go.


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