Myford Super 7 tailstock taper turning adjustment

[Phil H1Participant @philh196021]

Any Myford Super 7 users out there?

I have noticed a misalignment of my Myford Super 7 tailstock so I put a DTI on the face plate and rotated it round the tailstock barrel. This confirmed a 10 thousands of an inch offset of the tailstock.

So an easy fix I thought. Simply move the tailstock body across on its base in accordance with the manual and away I go.

The manual simply says to unlock the tailstock body from the bed and use the two screws either side of the tailstock to slide the main body across but absolutely no joy. Have I missed another retaining screw that prevents the body moving across on its body or is the tailstock jammed somehow?

Thanks,

Phil H

[Phil H1Participant @philh196021]

[Martin ConnellyParticipant @martinconnelly55370]

It may be better to measure the bore rather than the outside of the barrel. Any non-concentricity will cause problems otherwise.

Martin C

[egaParticipant @ega]

As far as I know there is no other retaining screw but it might pay to take the tailstock off its base, clean the mating faces, oil and reassemble.

The adjustment via the two pusher screws can be a little counter intuitive; check the manual drawing to confirm which way to move them.

[Phil H1Participant @philh196021]

Thanks Martin. A little bit more force on the rear adjusting screw and the body finally started to move across on its base.

The lathe was bought brand new in about 1975 and has only been used for about 20 hours up till I acquired it about 10 years ago. I guess the tailstock has never been adjusted from new and was just a bit stiff and a bit resistant.

I will now clock it up using the outer barrel and bore and check the longitudinal adjustment too.

Phil H

[Phil H1Participant @philh196021]

Thanks Ega, it took just a tiny bit more force on the screw than seemed right. It is now moving quite freely.

Phil H

[egaParticipant @ega]

Phil H:

You are lucky to have a virtually new example and it would be interesting to know in due course how close you can get to perfect adjustment.

As you no doubt know, over time wear between base and bed causes the tailstock to droop.

[Phil H1Participant @philh196021]

Thanks Ega,

Yes, I am very lucky. The machine was bought by my dad in about 1975ish. It finally got a tiny amount of use in the mid 80s (about 20 hours) and I have had it now for almost 10 years. It is mechanically pristine but the cabinet and a few other bits suffered with a touch of rust that took a little bit of work to remove.

I have been using my larger plunger type DTI so far and I have adjusted the horizontal plane (front and back of the barrel) to within 0.001" – so that is much better. Unfortunately, the vertical (top and bottom) is a mile out at the moment for some reason. More investigation required.

I haven't used my finger type DTI yet on the bore of the barrel because the mini magnetic base doesn't fit the DTI properly – or vice versa. The base needs modification. Still, I have plenty of time to adjust the base at the moment don't I?

Phil H

[Martin ConnellyParticipant @martinconnelly55370]

If you have a centre (or chuck, drill etc. ) with a good finish and no damage you can put that in the tailstock and use your plunger DTI on it. Check it in a couple of rotated positions to average out any error if you are not sure of its quality.

Martin C

[DMBParticipant @dmb]

An old idea I've seen in a book is to put the faceplate on with both head – and tail – stock centres in. Use centres to hold a bar of metal by the hole in it at one end and swivel bar by hand around in front of the faceplate like a clock face and minute hand. Note varying space, if any, between outer end of bar and faceplate. This magnifies any discrepancy. Not tried it on my Myford or the fb Drummond I had previously, just what I saw in a book.

[HopperParticipant @hopper]

Or see the article in MEW issue 290 on Beginners Guide to Tailstock Adjustment.

Tailstock is commonly made a couple of thou higher than headstock to allow for wear. If you have more than that it is most likely due to poor assembly between tailstock body and base. Often swarf, paint or burrs in the interface.

[HopperParticipant @hopper]

And make sure tailstock is firmly clamped down and barrel clamp is also tight when doing alignment. B

[Phil H1Participant @philh196021]

Thanks for the tips chaps.

I finally got round to making a small adaptor to allow my finger DTI to be loaded onto my small magnetic base which is a handy thing to have. However, I managed to load the finger type DTI directly into a headstock collet and I positioned the stylus in the bore of the tailstock.

After a minor tweak, the front to back run out was less than +/-0.001". I tried moving the barrel to its maximum out, mid and retracted position and the same +/-0.001" was observed. All these measurements were carried out with the barrel and tailstock firmly clamped.

The vertical (top to bottom) run out is +/- 0.005" and it looks like the tailstock is 0.010" high. I will try removing it to see if there is any debris.

But even with this 0.010" discrepancy, I tried drilling some steel and it seems far, far better than it was. Before I made the adjustments, the tailstock chuck would tend to disengage from its Morse taper quite easily and start spinning in the barrel.

Thanks everybody.

My next task…. I'll check for swarf under the tailstock then finish off a rear tool post that I started ages ago.

Phil H

[not done it yetParticipant @notdoneityet]

You will likely wonder why you hadn’t finished that rear tool post an age ago – as parting-off will be improved🙂

[NorboyParticipant @norboy]

Hi Phil,

Seeing your efforts I thought I would check the tail stock on my Super7. It transpires it is about 0.002” out.

Given I have some time I thought I would see if I could improve on this.

I turned to the Myford manual – not always the best example of clarity and detail – and remain a little bit uncertain.

Firstly am I correct in assuming that aside from releasing the bed clamp there are no other screws to deal with apart from the two set over screws?

Secondly is it simply then a case of say screwing in the rear side screw to push the tailstock toward the front, having first loosened the front screw and vice versa if the tailstock has to move towards the back?

Your advice or that from any other myford user appreciated.

Alan.

[Phil H1Participant @philh196021]

Norboy,

You are correct. The Myford manual seems vague when you first look at it but it is correct i.e., loosen the bed clamp and adjust the screws either side of the tailstock. Just make sure you loosen and tighten the right screws because the tailstock gib strip screws are close by at the back.

Adjusting is not quite as you have described. You tighten the rear screw to make the tailstock slide away from you (having loosened the front screw first of course) and vice versa.

Please ensure that you have a really nice fit on the screw driver because it is easy to damage the slots and you do need a little bit of umph if the tailstock has not moved for a while.

Phil H

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