Boring the MT2 on spindle

Any of you guys on here used a Mt2 reamer ,if so how were your results . The boring bar I have isn't quite rigid to be as accurate as I'll need . So I'm planning to bore out the taper as far as I can then finish it with the reamer .

My concern about trying this is if the reamer goes off centre .I have stated in another post I that making the spindle was the easy part .... Let me correct myself ,I didn't take the MT2 into consideration ,the rest of the spindle yes but not the taper ,it's the main part of the whole shi-bang get it wrong and the part gets binned .

Interested as always to here you thoughts .

Sean

Sean,

My first thought would be to bore/ream the taper socket first [in an oversize blank] and then turn the rest of the job between centres.

MichaelG.

Or you could cheat and use a 'blank end arbor'. Arc sell the male 2MT type - the 2MT female type used to be an 'over the counter' stock item at big ironmongers/tool merchants. I bought one years ago from Buck & Ryan in Tottenham Court Road but the female version seems to have become a rarity in recent years.

The female arbor should come with a short MT plug with a centre drilling to permit the entire arbor to be machined between centres. Such a plug would continue to be useful for other projects once machining of its 'arbor of origin' is complete.

Best regards,

Swarf, Mostly!

Hi Micheal,

The taper was going to be my first port of call ,The material I'm going to be using is a good bit oversized .

Sean

Picking-up on Swarf's line of thinking:

Many years ago I used a commercially available MT2 socket in a simple cylindrical body [all nicely ground], to upgrade an existing lathe spindle ... I simply bored the the spindle in-situ and fixed the MT2 socket with Loctite 638.

MichaelG.

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Chronos appears to sell something similar ... listed on this page:

https://www.chronos.ltd.uk/acatalog/Quick_Change_Toolposts.html

Edited By Michael Gilligan on 16/11/2017 20:28:11

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Then I don't quite understand the concern that you expressed in the opening post:

" My concern about trying this is if the reamer goes off centre"

MichaelG.

The technique I was taught for boring and reaming Morse Tapers was to bore a series of steps to approximate the taper before finishing with the reamer.

Don't sweat the small stuff.

Set your top slide angle by mounting a MT2 adaptor etc between centres (reverse centre the one end) and use a dial indicator on the toolpost to match the angle.

Bore the taper as close as you can with the largest boring bar that will fit in there. Take fine cuts toward the end of the process. Use a very sharp, pointed HSS tool bit to minimize chatter.

For the last few thou, use your MT2 reamer with guidance from the tailstock centre. Turn the lathe chuck by hand or crank handle and proceed gently gently. It will follow the taper and go straight. You are only cutting a couple of thou to finish off with.

If it were to end up not quite right (unlikely), big deal. The only time it's critical is when turning between centres, and it's customary to use a soft centre and turn it true in position when doing this anyhow.

Not sure what your lathe is but I have found that with gap bed lathes such as Myford, Drummond etc you can't really turn between centres using the headstock centre as that end of the job is too far away from the carriage without running it off the end of the bed ways. So I always mount a soft centre in the three jaw chuck, turn it true and engage the drive dog with a jaw of the chuck.

Edited By Hopper on 16/11/2017 23:37:43

It's for a milling head not a lathe

Sean,

I'm not sure to whom you are making that response, but I will assume that it's me.

If you make the taper socket first, and the workpiece is oversize, then [within reason] it doesn't matter exactly how accurately it is aligned in the bar ... The crucial bit comes when you now turn the outside diameters around it [working between centres].

It may help if you post a detail drawing of the design.

MichaelG.

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P.S. ... If I was making a milling spindle from scratch, I would avoid using Morse Taper [but I realise that you may have good reason to want it].

Edited By Michael Gilligan on 17/11/2017 08:37:00

The MT2 is taper per foot. It does not need to be the full lenth to be effective. It can be still effective even if the taper section is only 50mm long. You want the tool on centre to about no more than 0.05mm above centre. Do not have the bore bar below centre at all. Using bearing blue to check it also works very well. If you are out by 0.01mm in 50mm it will not make that much difference. It will stil work and need a drift to remove it .

Neil

The female MT blank end arbor is a length of mild steel bar with a female morse taper socket ready-machined in one end. It comes with a short plug fitting the MT socket and centre-drilled. The other end of the bar is (if I remember correctly) also centre-drilled so that the whole can be machined between centres. Apart from that, the other end is blank - hence the name, 'blank end arbor'.

I think I have one in my stash somewhere (sorry, not for sale - they don't call me 'Smaug' for nothing !), If I can find it, I'll post some dimensions and/or a photo.

Best regards,

Swarf, Mostly!

Before I started out in model engineering I was into wood turning as were a number of blokes around here, some of the lathes(most) around were "home made", and didn't have a taper bore in the spindle. I modified two or three of them by drilling the spindle using a Jacobs Chuck mounted on the tailstock. I drilled full depth with a drill to suit the small diameter of #1 MT the two other sizes part way down the bore then a #1 MT reamer until a # 1 center fitted ok. I then (a few months later) made some driving centers, about a couple of dozen actually when I bought my engineering lathe, sold most of them for $NZ 10 each. A bit rough but for wood turning worked well.

Ian S C

Michael, if the socket were formed first and the reamer wandered off as it went deeper into the hole then mounting with a ctr in the opening of the taper would probably not ensure concentricity.

If a male taper were mounted dead true or one cut in-situe at the headstock end then the embrio spindle mounted onto that for the remaining machining then all would be true to the socket.

Silly me. Why did I not know that?

Somewhere I have read that an MT reamer should be allowed to "float" in the socket, which has been previously frilled and bored to as close to the taper as possible, not either held in a t/s chuck or even located on a centre, to avoid any inaccuracy in the T/S centering taking the socket off-centre.

The Dore-Westbury kit IIRC came with a short MT2 tapered plug with a centre hole in the outboard end. The spindle blank was supplied with the socket bored, and you were supposed to mount it between centres using the plug in the socket to locate the T/S centre.

Hi there, Sean,

Here is a photo of a female 2MT blank end arbor:

The dimensions are as follows:

Overall length: 8½ inches,
Maximum diameter: 1¼ inches,
Reduced section diameter: 1.188 inches,
Length of reduced section: 3¾ inches.

As you can see from the photo, there is a slot for an ejector wedge/drift. The 2MT centred plug is rather long compared to the one I bought all those years ago in Buck & Ryan's. The back end of the arbor does have a centre drilling.

I hope this helps.

Best regards,

Swarf, Mostly! (aka, in some quarters, 'Smaug' )

On the right is the taper plug - the centre drilling is at the other end. On the left is a double-ended MT2 arbor I made. One end was turned to a taper and carefully fitted to the h/s socket in my lathe; then the whole thing turned round and fitted back in lathe taper with a drawbar to hold it while the other end was also turned to MT2, with another drawbar socket. I made this to allow making a short spindle, with an MT2 socket made in it, to be mounted to have its o/d turned concentric with the taper. You are welcome to borrow either or both of these, I don't suppose they would otherwise get used.

It strikes me that using the type of arbor shown above could be difficult as it is surely hardened and ground. You can buy MT2 sleeves with parallel outsides, which you can loctite into a parallel bore in your spindle - I think RDG or Arc have these.

If this is a milling spindle, you could be outrageous and not have an MT2 taper at all! Why not make the end to fit an ER25 or 32 collet? Then you only have to make a short taper, which is quite easy, I've made both ER25 and ER16 tapers that work fine. Or bore a parallel hole and loctite an ER25 or 32 straight shank collet chuck into it. There have been plenty of postings here on why Morse tapers are not the best for a milling spindle.