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3MT quill

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Tony Jones 318/08/2010 16:16:08
4 forum posts
Hi all,
           I have a old milling machine with a 3MT quill, the problem is I cannot  use a lot of my tooling in it as the 3MT tools must have a flat section that fits into the quill, is there a conversion that will allow me to use an ordinary 3MT and also pass the drawbar through.
 
Thanks. 
Bogstandard18/08/2010 18:06:55
263 forum posts
You don't mention what mill it is. But I doubt, if it is that way out, you would be able to get anything to convert it.
 
Is the spindle drilled all the way through from top to bottom?
 
If it doesn't, then there is nothing you can do, unless you put a hole thru it yourself. Then it would just be a matter of getting a drawbar made and standard no tang tooling should fit.
 
I would say, because it only has a tang fitting, it is actually a drilling machine, not a mill.
On a drill, all the pressure is in a downwards motion, so a tang fitting is fine, on a mill, there are significant side loads on the quill, so it has to have a drawbar to stop the MT fitting from falling out. You will also find, that a drilling machine bearings will not stand up to the side forces required for milling, and would soon collapse.
 

Bogs
John Stevenson18/08/2010 21:11:58
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5068 forum posts
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Is this an Arboga mill, they had a MT3 quill that takes tang tooling but the collet holders had a screwed ring that fitted over the chuck onto the spindle to stop it walking out.
 
These have a hardened spindle and can't be drilled though because the gearbox is in the way.
 
John S.
David Clark 118/08/2010 21:29:36
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3357 forum posts
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Is this an Arboga mill, they had a MT3 quill that takes tang tooling but the collet holders had a screwed ring that fitted over the chuck onto the spindle to stop it walking out.
 
These have a hardened spindle and can't be drilled though because the gearbox is in the way.
 
John S.
Reposted by David Clark
Thanks John
Tony Jones 319/08/2010 09:17:02
4 forum posts
Hi, Thanks,
                         I did not discribe it well, ! the quill takes 3MT tooling and has a drawbar , the 3MT tooling must have flats at the end of the taper that fits in the quill to stop it from turning as well as the drawbar, my mill is a FRITZ WERNER 3.230, it is a big heavy machine and works well, I do not have a manual or anything for it.
 
Thanks 
Bogstandard19/08/2010 10:33:29
263 forum posts
Tony,
 
You will find that a 3MT is classed as a self locking taper, that is where if both male and female are in good condition, they will lock up almost solid just by pushing up on the taper.
 
That is how most MT quills work in milling machines, and so does not require the tang to tighten up, just either a method of locking the quill while you tighten up on the drawbar, or a spanner on your toolholder which will do the same sort of thing.
 
The tang fitting is also standard in most mills with an MT taper, that is so the mill can be used as a drilling machine using the larger sizes of drills that have an MT taper and tang. That allows you to quickly change drills by using a tapered drift thru the slots in the side of the quill to release the drill rather than having to undo a drawbar.
 
So you should find that your MT tapered tooling without tangs should work just fine using the drawbar you have.
 
But you must take care which type of thread is used on your drawbar, because tooling can normally come with two different types, and you will have to get another drawbar turned up with the other thread on, just so that you can mount either type into your machine.
 Have a look at the top ones on here, it shows that you can order one of two types for MT3, one with a M12 thread or another with 3/8" Whitworth. I would suspect your drawbar, as it is continental, to have an M12 thread.
 
 
Just a warning, unless you have a self ejector on your drawbar, it can take some serious persuasion to get the MT taper to seperate, and I would suggest you invest in a good dead blow or lead hammer, to prevent damage to the drawbar top.
 
I hope this helps.
Tony Jones 319/08/2010 11:08:52
4 forum posts
Thanks,
                 I have made a couple of drawbars with different threads and use a dead blow/copper hammer  to nock  them free, the problem I have is , take for instance , a 3MT fly cutter ! it will not fit in the quill because the MT taper does not locate before the tool head hits the end of the quill,  the reason being the  flats between the taper and the tool head are not there on a lot of the tooling I have. also there are no slots in my quill to allow a taper drift.
 
Thanks 
 
Keith Long19/08/2010 13:13:53
883 forum posts
11 photos

Hi Tony

Are you sure the taper in the mill is 3MT? Brown and Sharpe tapers are virtually the same taper angle but a shorter length, if I've read the tables correctly, so would seat in the mill spindle. Even though the tapers are very similar as far as I know they are NOT interchangeable.

Keith

Tony Jones 319/08/2010 14:48:32
4 forum posts
Hi Keith,
                   Yes it is 3MT, I have searched on the web for a manual, found one but they want over £100 for it, seems a lot to me.
 
Thanks,
                     Tony 
Stub Mandrel20/08/2010 21:51:54
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4318 forum posts
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Hi Tony,
 
Why not just grind two flats on each MT3 taper?
 
It shouldn't spoil them for use in other machines.
 
Neil

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