Myford (Super) Seven tailstock locking lever

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Myford (Super) Seven tailstock locking lever

This topic has 17 replies, 5 voices, and was last updated 17 May 2017 at 15:42 by NJH.

Viewing 18 posts - 1 through 18 (of 18 total)

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15 May 2017 at 12:53 #298223
ega
Participant
@ega
I find I sometimes need to re-tighten the lever when drilling from the tailstock by bumping with the heel of the hand. This also struck a chord in the memory and with the help of Alex Cameron's ME index I was able to locate an article by Arnold Throp in ME 1983 3716 p520 which describes his modifications to the locking levers to address this apparent problem. It seems that AT was suffering from "Dupuytren's contracture" which "afflicts men who are heavy drinkers and men who use tools!"

As a first step I dismantled, cleaned, lubed and readjusted my tailstock which seems slightly better for this elementary attention. The eccentric is located laterally by a grubscrew protruding into a groove, a point which is not obvious from the illustration in the manual (to get at the grubscrew it is necessary to undo the adjusting screw on the lever side of the casting).

On my machine there is a pin in this groove which contacts the grubscrew when the lever is in the loose position and prevents the lever dropping beyond the horizontal. Again, this feature is not shown in the manual and I wonder whether it is a modification by a previous owner.

I am thinking of re-making the eccentric and lever and gave some thought to suitable material for the eccentric which has to resist bending in use. I have a large HT bolt which seems likely to be suitable.

Questions to Myford users:

Is the pin mentioned standard and do your levers drop?

Are you happy with the action of your levers and, if not, have you done anything about it?

As mentioned above, the situation was improved by a stripdown and I guess that in use swarf can interfere with the action of the clamp. Some time ago I fitted a front wiper to the tailstock base but it is obvious from the state of the clamp that debris has at some stage got into the interface between clamp and the underside of the bedways. There is also the point that the lever needs to be adjusted to the optimal position via the nut on the eye bolt.
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15 May 2017 at 12:53 #12975
ega
Participant
@ega
Construction and possible modification
15 May 2017 at 13:57 #298234
Sandgrounder
Participant
@sandgrounder
My S7 Mk1 lever drops to a vertical position when the tailstock is unlocked.

John
15 May 2017 at 18:54 #298287
ega
Participant
@ega
Sandgrounder:

Thank you for your reply which suggests that my pin is indeed a modification.

I recall that someone suggested a modification to GHT's VDH to prevent the clamp lever collapsing.

I would be glad of further comments. My Harrison Graduate has a similar clamp arrangement and the lever is about half as long again.
15 May 2017 at 19:17 #298292
Robbo
Participant
@robbo
Ega

The pin is standard and has been on the several tailstocks I have seen in pieces. Or should I say the evidence of it has been there. In many cases heavy-handed use of the lever, and the ignorance of the pin's existence, has resulted in the pin being sheared off. Drilling out and replacing has restored the tailstock to normal. Once sold on to a new user, with a sheared pin, the ability to completely rotate the lever is regarded as normal.

Without the pin the lock can be applied in two directions. With the pin the lever should come to rest more or less horizontally.

The pin is not shown in the tailstock drawing in the Manuals, indeed the end of the eccentric with the groove is hidden from view, only the grubscrew is shown and mentioned.

I have had no problem locking the tailstock on the bed with the standard arrangement, but it does call for careful adjustment of the Nyloc nut on the end of the eye bolt so as to give enough freedom to operate without any sloppiness.
15 May 2017 at 19:24 #298293
Sandgrounder
Participant
@sandgrounder
Posted by Robbo on 15/05/2017 19:17:57:

Ega

The pin is standard and has been on the several tailstocks I have seen in pieces.

That's interesting, I'll have a closer look at mine tomorrow,

John
15 May 2017 at 20:01 #298299
Neil Lickfold
Participant
@neillickfold44316
On my S7 there is a Nylock nut on the bottom of the unit like you describe. It is set so that it locks at about 10:30 or 1:30 depending which side you are looking at it. I can't remember that last time it was taken apart and adjusted. The secret is to keep the area under the the bed where it pulls up to clean. I have a leather cover on the front of the saddle and occasionally clean under there with a paper towel. When drilling, I back up the saddle to the tail stock. This leaves almost no gap for stuff to get down there and to be trapped on the under side. I find brass to be the worst for some how making it's way to stick to the underside of the bed .

Neil
15 May 2017 at 21:12 #298321
ega
Participant
@ega
Thanks for these comments.

I aimed my post at both Super Seven and ML7 users because it seemed possible that the tailstock clamp arrangement on both machines was similar. As it happens, the illustration of Len Mason's ML7 on the front of his excellent little book clearly shows a drooping lever; what do ML7 owners say?

Robbo:

It seems clear from your post that the pin originated at Beeston. On mine, the pin had apparently not been inserted far enough and the head has been rather crudely filed down to clear the bore in the casting. Locking in the reverse direction seems counter-intuitive but might well give firmer clamping and less concern to the heavy drinker!

Neil Lickfold:

A Myford user friend in New Zealand came up with a rather refined modification of the clamp which was spring-loaded so as never to lose contact with the underside of the ways – effectively, a lockable slide. I agree about brass: gets everywhere, splinters can be hard to remove, grabs at the drill and can't be removed with a magnet!

I will keep an open mind for the time being about re-making the unit
16 May 2017 at 07:59 #298374
Sandgrounder
Participant
@sandgrounder
Posted by Sandgrounder on 15/05/2017 19:24:47:

Posted by Robbo on 15/05/2017 19:17:57:

Ega

The pin is standard and has been on the several tailstocks I have seen in pieces.

That's interesting, I'll have a closer look at mine tomorrow,

John

Had a look this morning and there's not much to see unless the whole thing is taken apart, I'll just have to assume that it was there and has been broken off.

John
16 May 2017 at 12:18 #298406
Robbo
Participant
@robbo
John

You can only see the pin if you take off the baseplate so as to loosen the grubscrew that holds the eccentric in place, and pull out the lever and eccentric together. Not worth doing just for curiosity!.

Ega

I have a spare ML7 tailstock (the "Mk 2" type) which I have dismantled and the arrangement is the same as the Super 7. With the pin doing its job then the lever stops horizontally when slackened off.

I also have a Super 7 tailstock (also a "Mk 2" type, with the locking lever on the top) in pieces, and this is the same as the earlier tailstocks I have seen. (This one is in bits because it has a capstan operating conversion which won't fit – the thread in the body casting needed relieving ).

One of the problems with the arrangement is the pin is of soft material, whilst the grubscrew is hard. The pin doesn't protrude much and if the grubscrew is not fully entered then the resistance can easily feel like gunge in the works and the screw will easily ride over the end of the pin.
16 May 2017 at 15:33 #298428
Sandgrounder
Participant
@sandgrounder
Posted by Robbo on 16/05/2017 12:18:26:

John

You can only see the pin if you take off the baseplate so as to loosen the grubscrew that holds the eccentric in place, and pull out the lever and eccentric together. Not worth doing just for curiosity!.

Thanks for that advice, I'll leave it alone.

John
16 May 2017 at 16:44 #298439
Robbo
Participant
@robbo
John

Especially as I didn't mention that removing the base will of course ruin the alignment, so you'll have to that again
16 May 2017 at 17:30 #298445
ega
Participant
@ega
Robbo:

You mention the barrel locking lever (with which I am perfectly happy); do you happen to know why Myfords made the change to put the lever on top of the casting?

I had always assumed that it was felt that a vertical pad bolt would be less likely to deflect the barrel up or down and that any sideways deflection could be adjusted. More recently I saw the suggestion that the new position was intended to avoid conflict with the rear toolpost.

I think the explanation for the absence of any reference to the pin on the manual drawing is the simple one that it is part of the "assembly".
17 May 2017 at 13:58 #298556
Robbo
Participant
@robbo
Ega

Don't know why they changed the locking lever to be honest. Both the old and new use the same sort of split pad with a round cut-out so the tightening effort is centralised anyway, side-to-side with the old and up-and-down with the new.

I have no problem with the side lever fouling a rear toolpost – my rear toolpost is mounted on the back two T-slots and at the front of the cross-slide, so the body of the tailstock hits the saddle before the lever can hit the toolpost.

Depending on the adjustment the body locking lever and the barrel locking lever could foul each other (dirty beasts!) but that has never been a problem.

The top lever is easier to get hold of though.
17 May 2017 at 14:31 #298561
ega
Participant
@ega
Thanks, Robbo.

I forgot to mention that the top-mounted lever *would* foul my Radford QC tailstock tooling, a circumstance that goes some way to reconcile me to the age of my machine!
17 May 2017 at 15:03 #298562
NJH
Participant
@njh
I'm a bit confused here. My S7 tailstock lever is at 12 0'clock ( or maybe 2min past 12 0'clock) when locked to the bed and at 3 0'clock when free.

Norman
17 May 2017 at 15:14 #298565
ega
Participant
@ega
NJH:

You are running (correctly) on Myford time.

We had moved on to discuss the barrel locking lever.
17 May 2017 at 15:42 #298568
NJH
Participant
@njh
Ah Ega – the story of my life – always a bit behind things! In this case I blame our daughter.. we met up with her in town and had a very pleasant lunch to celebrate her birthday today – I must have lost the drift!

Norman
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