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Mt3 extension for tailstock

Does anyone use one?

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Stuart Cox 301/05/2021 18:09:37
145 forum posts
25 photos

Has anyone used a morse taper extension on their tailstock to improve the reach? Just wondered if this is a possibility or does it create too much wobble/inaccuracy?


Martin Kyte01/05/2021 19:13:26
2607 forum posts
45 photos

How does that improve the reach? Isn't it like having a lathe with a shorter bed?

regards Martin

Oily Rag01/05/2021 19:18:47
523 forum posts
163 photos

Never used an extension, I presume here you have a 2MT socket in your tailstock barrel and want to use a 2 to 3 MT convertor. What I did was I made a #3MT tailstock barrel, forced upon me by the fact that the ex-school Emco Maximat S11 had suffered at the hands of the 'yoof' and the tailstock barrel had been detached and used for unimagined purposes (or just thrown in the local canal!).

The barrel just happened to be 30mm diameter and in my 'scrap box' was a Go Kart back axle of 30mm ground bar (with a hole through it) but even better it had a 3mm keyway along the majority of its length. The tailstock had a 2.5mm key in it to radially locate the barrel - so a quick re-make of that to 3mm and I had the perfect new barrel. I made a PB bush nut to fix in the end of the tube for the leadscrew, and then reamed the barrel to #3MT (purely because the hole through the original axle suited a #3 MT minor diameter). The nose of the barrel protrudes about 40mm out due to the #3 MT would otherwise interfere with the keyway.

It's not too difficult to make a new barrel - and you can make it as long as you like. On my other machine (a Raglan LJ) I have a capstan operated tailstock, home made again, but using a Raglan 5" capstan tailstock casting for the rack pinion housing.


Stuart Cox 301/05/2021 19:28:36
145 forum posts
25 photos
Posted by Martin Kyte on 01/05/2021 19:13:26:

How does that improve the reach? Isn't it like having a lathe with a shorter bed?

regards Martin

The idea is it will extend the reach of the tailstock chuck so it can reach further over the saddle towards the chuck

Stuart Cox 301/05/2021 19:32:37
145 forum posts
25 photos

Thanks Martin, Im not actually looking to convert from mt2 to mt3. My tailstock is mt3 so I would be adding a mt3 to mt3 extension to improve the reach over the saddle

Regards Stuart

old mart01/05/2021 19:40:27
3398 forum posts
210 photos

Arc don't seem to have one, but Cutwell do:


Stuart Cox 301/05/2021 19:50:44
145 forum posts
25 photos
Posted by old mart on 01/05/2021 19:40:27:

Arc don't seem to have one, but Cutwell do:


Thanks for the link! I have found a few available but just wondered if anyone had used one in their tailstock?....

Stuart Cox 301/05/2021 19:53:21
145 forum posts
25 photos

..sorry, the correct terminology should be 3MT not mt3 🙄

old mart01/05/2021 20:10:07
3398 forum posts
210 photos

There is no reason not to if the work requires it.

Speedy Builder501/05/2021 21:09:04
2447 forum posts
195 photos

I have an M2M to M1F long extension and often use it as is or for putting pressure onto a die stock when cutting threads.

Stuart Cox 301/05/2021 21:48:50
145 forum posts
25 photos
Posted by Speedy Builder5 on 01/05/2021 21:09:04:

I have an M2M to M1F long extension and often use it as is or for putting pressure onto a die stock when cutting threads.

Thanks for your reply, do you notice any lateral movement when using the extension?

john halfpenny01/05/2021 21:50:54
191 forum posts
27 photos

I use one Stu, for short/small twist drills where the reach is a little short. My dro scale makes the saddle a little wider, so that even my reversed tailstock doesn't quite do the job20200630_100735.jpg

Stuart Cox 301/05/2021 22:10:43
145 forum posts
25 photos
Posted by john halfpenny on 01/05/2021 21:50:54:

I use one Stu, for short/small twist drills where the reach is a little short. My dro scale makes the saddle a little wider, so that even my reversed tailstock doesn't quite do the job

Thanks John, I think I will get one and give it a go 👍


Andrew Johnston01/05/2021 22:48:37
6316 forum posts
677 photos

I use a Morse taper extender in the lathe tailstock. It converts 3MT to 4MT when using larger drills than will fit in the tailstock. Seems to work fine, although of course drilling isn't considered a precision operation.


Andrew Moyes 101/05/2021 23:05:12
142 forum posts
23 photos

I have a '2MT to 2MT adapter' for my Myford. I find it very useful for some operations such as tapping or using small, and therefore short, drills. I bought it from Chronos. I didn't have great expectations for accuracy as it's almost certainly Chinese but was pleasantly surprised. The runout is about a thou. The resistance to lateral forces is not great, as you might expect, but it could support light turning eg clockmaking. It seems fine for axial loads though.


Stuart Cox 302/05/2021 08:19:33
145 forum posts
25 photos

Thanks everyone, I'm now convinced it will work for what I need!

I appreciate your replies


DC31k02/05/2021 08:24:21
586 forum posts
1 photos

If you are worried about droop or wobble, and if space permits, you can always snug the fixed steady fingers onto the extension.

john halfpenny02/05/2021 08:39:36
191 forum posts
27 photos

Here is my 3mt to 2mt extension, for comparison. Works well for me. From Arc.20210501_220110.jpg

Clive Foster02/05/2021 09:59:24
2882 forum posts
104 photos

Nice picture from john showing the main disadvantage of an extension in the tailstock.

Its too darn long! So you can't leave it in place all the time.

Especially if its a same size to same size one.

Due to the need to accommodate both MT shank and tang in the extension barrel you have around 4 inches or more of extension which is not only rather more than you need but also unnecessarily magnifies any alignment errors.

Pretty much all of our home workshop size lathes tend to be short in the tailstock and of limited travel. Around 2 to 2 1/2" of useful travel before inadvertently popping the tool out on retraction is common and just not enough in practice. Main reason I swopped my SouthBend Heavy 10 for a Smart & Brown 1024!

Many years ago one of the guys on the SouthBend Forum described his modifications to increase tailstock poppet travel to, I think, around 3 1/2" or a little more. He screwed an extension piece on the back of the tailstock to accommodate a longer poppet and feed screw. As I recall it he made the extension bore a little larger than the tailstock bore proper to avoid potential alignment issues.

As its a permanent modification you could ream the whole bore after fitting to ensure accurate sizing and alignment and make a larger poppet to suit.

He reported that the extra inch or so gave enough travel to eliminate reach over the cross slide issues and made drilling deeper holes much easier.

Its what I would have done if a bout of bad temper had not coincided with a £££ offer for the Heavy 10 the same weekend as a 1024 appears within collection range!


Nigel McBurney 102/05/2021 10:10:26
945 forum posts
3 photos

Step up sleeves are often regarded as a no no ,basicaly in the wrong hands it can seriously strain a tailstock,for instance a Colchester with 3 MT tailstock can take a 1 1/4 dia drill ,a 4mt step up sleeve would allow a 2in drill to be used a 3/4 inch dia increase would put a hell of a load on the tailstock sleeve key and keyway,similarly a 2 to3 step up would allow a Myford to drill with a 11/4 in drill. I knew a toolroom foreman who kept the very largest collets of Clarkson autolock chucks and jump up sleeves locked away and their use had to be approved,The extension sleeve on the other hand with similar MT capacity at each end can be useful for reaching over the saddle,one use is when setting up work on the face plate,lets say a flat plate requires a hole to be bored in it ,the position of the hole can be centre popped or centre drilled,the plate can the be held against the face plate,the tailstock with extension and a centre can be advanced towards the the work so that the centre engages with the centre pop,pressure from the tail stock can hold the work in place and clamps fitted.Without the extension the tailstock on many lathes will foul the saddle before the centre can reach to the work.

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