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Re-grinding 2 MT Socket

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Stephen Osborne04/01/2021 15:52:31
31 forum posts
4 photos

The 2MT socket in the spindle of my milling machine is damaged and will not hold a chuck true. I have a 2MT reamer but as the spindle is hardened, I will not attempt to correct the taper myself.

Does anyone know of a company who could precision re-grind the socket on my spindle?

I have contacted a couple of enterprises from an internet search who did not want to know. I work on the theory that there is always somebody out there who can do what you require.

Happy New Year


Pete Rimmer04/01/2021 16:07:03
1255 forum posts
69 photos

If you want a professional outfit then spindle services in Coventry.

If you want to take a chance on home-grown grinding then anyone with a tool post grinder and a taper attachment or long-travel compound on a good lathe should be able to do it.

Another option is to tilt the head over to the taper angle and use a cermet insert in a holder on the table and machine it using the z-axis. It would require very careful setting up but it should work.

Howard Lewis04/01/2021 16:07:45
6297 forum posts
15 photos

Would it be worth sacrificing a 2MT fitting (Sleeve,/ broken drill ) to use it to lap the bruises out of the socket, with valve grinding paste, followed by a thorough clean?.

Scores below the surface will remain, but you should have a much greater contact area with whatever tooling is used in the socket.


Dave Halford04/01/2021 16:20:34
2091 forum posts
23 photos

Dremel just on the bruises should do it

John Hinkley04/01/2021 16:39:46
1353 forum posts
430 photos

Just a quick thought. Are you absolutely certain the spindle is through hardened? If the morse taper is damaged, it can't be that hard, surely? I'd try the taper reamer if it were mine, but I'm not a qualified engineer. Those that are will soon put me right. If it doesn't work, you'll have to have it ground anyway.



Edited By John Hinkley on 04/01/2021 16:40:30

Baz04/01/2021 17:30:03
755 forum posts
2 photos

If it were mine I think I would try the morse taper reamer, if the spindle taper is damaged it cannot be that hard, a HSS reamer should be harder, what have you got to loose, only a morse taper reamer and they are easily and fairly cheaply replaced. You don’t say what make of machine it is, if it is still in production could you just buy a new spindle?

Oldiron04/01/2021 17:35:10
995 forum posts
40 photos

I am with Howard on this one. Use an 2MT drill shank to massage the bumps out.

Highly unlikely that the damage is so bad that a good lapping will not bring it back to usable condition.


Dave Halford04/01/2021 17:48:20
2091 forum posts
23 photos

The trouble with lapping is it puts equal pressure on both the damage and the opposite good side. Does it not?

Pete Rimmer04/01/2021 19:10:03
1255 forum posts
69 photos
Posted by Dave Halford on 04/01/2021 17:48:20:

The trouble with lapping is it puts equal pressure on both the damage and the opposite good side. Does it not?

Yes, not only that but the raised spot will tend to wipe the lapping slurry off the lap.

Tapers are easy to ruin by lapping because you can only lap in one position. It's easy to lap waves in a part. Far better to die-grind a lump into a hollow then lap very slightly for a good fit, than try to lap down a lump.

Edited By Pete Rimmer on 04/01/2021 19:10:34

Nigel Bennett04/01/2021 19:17:31
460 forum posts
20 photos

B Kemp Grinders of Liversedge West Yorkshire (01924 408832 ) did my Boxford tailstock last year for me - 3MT. They struck me as extremely competent and it wasn't a bad price - about a hundred quid. Cheaper than a new barrel! They had test gauges to confirm the sizing. You aren't likely to get anything for less than that - it's setting up that takes most of the time, along with the specialist grinding equipment and the knowledge of how to use it.

Usual disclaimer.

Stephen Osborne05/01/2021 10:39:08
31 forum posts
4 photos

Many thanks gentlemen for all your constructive comments. The machine is a Tom Senior M1 and the problem appears to be at the mouth of the socket. On checking with engineer's blue, contact seems to be a ring around the large end of the taper with little contact with the rest of the taper. I will upload a photo when I get a minute.

Perhaps I am being too cautious and should try the reamer as Baz & John suggest.

Dave Halford05/01/2021 11:02:23
2091 forum posts
23 photos

According to the site the M1 should be this extract -.

the M1. With both a 3-speed direct belt drive and a lathe-like "backgear" slow-speed drive built into the main column (the latter mechanism also incorporated a two-speed belt drive), this very robust little miller had twelve spindle speed of: 60, 86, 104, 136, 169, 267, 329, 537, 642, 845, 1050, and 1660 r.p.m. The 2-speed backgear assembly was an important addition for it did much to extend the scope of the miller's versatility - especially the ability to take very heavy cuts when used as a horizontal machine Instead of being flange mounted, and buried deep inside the oily recesses of the machine, the 1 h.p. 3-phase motor was fastened to a height-adjustable plate, conveniently mounted on top of the main column thus making motor replacement a simple matter - it being possible to fit almost anything to hand that was powerful enough. The spindle ran in Timken taper roller bearings and was fitted first with a No. 3 Morse taper and then, following the general machine-tool trend, with the superior No. 30 International - a type that allowed heavier cuts to be taken yet with greater ease of removal and replacement.

So MT2 sounds non-standard

Stephen Osborne05/01/2021 11:22:20
31 forum posts
4 photos

Thanks for the reply Dave, but the Lathes & Co writeup is incomplete.

The machine is a Universal mill and the 3MT/30Int refers to the horizontal spindle. The vertical spindle is 2MT as standard!!

I queried this some time ago but was assured by the experts that 2MT was quite adequate for this size of machine. I think they should have fitted 3MT from the off.

Dave Halford05/01/2021 12:17:00
2091 forum posts
23 photos


It's just that "contact seems to be a ring around the large end of the taper with little contact with the rest of the taper" sounds like it's not the taper you expect.

Howard Lewis05/01/2021 15:02:35
6297 forum posts
15 photos


The taper used as gauge that is showing the "ring around of the large end of the taper" MUST be an accurate 2 MT. (Not something similar such as a Brown and Sharpe! ) Otherwise it is useless as a gauge for a 2 MT taper.

If you are unaware, you should only check a 2 MT with a 2 MT gauge, not the small end of a 3 MT.. The angle of Morse Tapers all differ slightly as the size changes. The only one that I can remember is 2 degrees 52 minutes for 2 MT, but all the others are different.

(Check on Google to find charts giving the tapers for various Morse tapers )

ASSUMING that the "gauge" IS accurate, with the contact only being at the large end, is it possible that the part has been bruised and closed in? This would cause a ring on the gauge where just the bruise makes contact and wipes off the blue.

Have you tried (have you the equipment? ) clocking the large end of the taper, to check for it being out of round?

If it is that easily bruised, the part may well be soft. In which case gentle use of a 2 MT reamer may put things right fairly quickly.

Hope that these comments give some help


old Al05/01/2021 15:12:09
186 forum posts

if it were mine, i would bin it and buy another. They are cheap nowadays.Waste your time on something more interesting

Dave Wootton05/01/2021 16:44:54
316 forum posts
66 photos

Re Spindle services, Coventry I had the spindle assembly from a Hayes Diemaster mill reconditioned by them a few years ago, The spindle was bent, the bearings shot and the taper damaged. They completely rebuilt it with new bearings, recut keyway for the quill drive, reground taper ( 2MT) it was superb afterwards.

As I was a private individual they kindly went gently with the cost as long as I was prepared to be a little patient so they could fit it in between other jobs, i think it was a couple of weeks turnaround. Around seven or eight years ago the cost was in the region of £350, which included the bearings which seemed very reasonable considering the amount of work required, and the fact it came back as good as new.

Given the cost of a Tom senior vertical head it's probably worth consideration.


I recommended them to a friend who had the horizontal spindle from a Centec taper ground by them, I believe he just sent them the bare spindle, I know he was pleased with the result.


Edited By Dave Wootton on 05/01/2021 16:49:07

Gavlar05/01/2021 17:20:41
105 forum posts
5 photos

Another vote for Spindle Services here.

I had a bent spindle on my Boxford X10. (See the thread I started some months back) I aggravated the issue by trying to grind the face of the spindle true (not admitted in the thread I started, too embarrassed!)

I nearly broke the lathe for spares before finding Spindle Services on the net. I called them, Simon the MD called me back, I explained the issue and he said what he could do and gave me an estimate over the phone. I sent them the spindle and they were true to their word and stuck to the estimate. The spindle was returned to me within about two weeks as good as, if not better than new.

They can straighten, replace missing metal and regrind to original specs. They are freindly, reasonably priced and easy to deal with.

Oily Rag05/01/2021 19:04:46
540 forum posts
184 photos

The 2MT socket should be soft(ish), but it will be tough. I have re-cut both headstock spindle tapers and tailstock barrel tapers with a good quality reamer, usually by hand not under power.

For heavily damaged items, I had a spindle that had been butchered to remove it at some point in its life, I can also fully recommend Spindle Services off Red Lane in Coventry, they straightened, metal sprayed and reground the spindle to as new.

If you ever get the chance to visit them take a look at the old COW building (COW = Coventry Ordnance Works) where the 16" Guns were made for the WWI dreadnoughts. If you can manage to get into the main shop the whale oil pits are (or were) still there where they hardened the barrel sleeves and also heated the outer sleeve to shrink them on. Underground near to where Spindle Services are located in an out building was the subterranean firing range where they tested the field artillery pieces. The tunnel extended for about 1/2 mile towards the old brick works off Stoney Stanton road. History lesson over!

Edited By Oily Rag on 05/01/2021 19:05:20

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