Ha ha, maybe the abusive previous owner needed to mount something longer than the bed? ie from tailstock centre to back of chuck was not quite enough…. Or perhaps fell asleep while taking a cut on a job and was using a boring bar an Iinch and a half longer than needed?

This thread should be in the 'tool abuse' thread!

Edited By not done it yet on 14/02/2017 15:24:59

No it’s not. Out on site at moment so post later but now you have the chance to drag the design kicking and screaming into the 19th century

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I think John was being nothing more than flippant and tongue in cheek.

Nick

Could be long – go get a coffee or a drink of tea and anyone of a mild disposition or who has Myford grey in their veins might do better to log off..

First off and this is just my take on it the only reason for the MT2 in the spindle nose is to run work between centres but the smart set can still do this by leaving the 3 jaw chuck on, placing a bar in the chuck and turn a centre on it and provided that you don't remove said bar then it will run perfectly true and you can use one of the jaws to drive the carrier. Nothing new, people have been doing this for years.

So this is a spare head stock off a ML7 with a MT 2 drill fitted to give an idea of where and how it goes..

Now this is an ER20 collet offered up to a reasonable decent spindle.

And the two compared.

As you can see the thick end of the ER20 is bigger than the MT2 but the small end is smaller than that part of a MT2.

However all is not lost. Seeing as out intrepid hero, Hooper has got a stuffed up spindle to start with he's nothing to loose.

So for your perusal here is a CAD [ clown assisted drawing ] of the spindle with bits superimposed.

Going from left to right in the centre we start off with a nominal 9/16" clearance hole as fitted as standard, this then develops into the MT2 and super imposed on this is the ER20 collet, all drawn to scale.

The ER 20 at the fat end is believe it or not 20mm diameter, so if the spindle was bored to say 22mm diameter for a depth of 1" and a slug of steel pressed and loctited in, then bored in situ at 8 degrees half included angle to accept an ER20 collet, all that is left is to make a new collet nut but with a 1 1/8" x 12 Whit form thread.

Job done and you now have a useful size collet system that can hold any size from 0.5mm up to 13mm.

Hopper,

Sorry I spelt your name wrong in my post.

If you are doing the ER 20 conversion you will have to bore out to 20mm plus to get the collet in.

[Edit] No forget that it won't matter, too late at night here and any size will do it's just that there will be a transition line somewhere along the ER taper which won't matter anyway.

The ML7 spindle is quite a simple piece of turning in a non exotic steel, I believe they used EN8 left soft on the white metal version and onece you are at this stage it would not be a lot more work to make a new spindle, with a flange.

D1-3 would be well overkill for a 3 1/2" lathe but a straight stepped flange similar to the Chinese C3, C4, C6 series lathes with a simple shoulder, no taper, would be very easy to replicate.

It would give you safe reversing, a source of cheap back plates and chucks.

Fitting is also very easy.

Stolen from the Mini late site of a review on the Sieg SC8 lathe.

The rotating plate has three keyhole-shaped holes that rotate through about a 15-degree arc. After the nuts on the studs pass through the large end of the keyhole, the plate is rotated to bring the small end of the keyhole into place. Then the nuts are tightened down on the plate to lock the chuck securely in place.

One advantage of this system is that you don't need to hold the heavy chuck in place with one hand while using the other hand to attempt to get the nuts in place in the limited space behind the spindle. Another advantage is that the nuts stay with the chuck, so are much less likely to get lost or to drop into the gap between the ways as you're trying to install them. A third advantage is that installing and removing the chuck is quicker.

I have this system on my TOS with A1-4 chucks fitted, it's quick as the nuts always stay on the studs and it's impossible for them to vibrate loose as sometimes the D series camlock can under interupted cuts.

With the state of the Faceplate, pity that the lathe has not got Power Cross Feed! Although whatever the shortcoming of your hand feed might be, it will be nothing compared to what has gone before.

Good work to be rectifying the brutality meted out by the former users.

Stick at it!

Howard