Myford S7 – Type 1 clutch – advice sought

[Liam Scanlan 1Participant @liamscanlan1]

Hi all,

I am new here, so please be gentle with me!

Unfortunately, I am also very new to the field, never having any formal machine training whatsoever. So please bear with me.

I have an early Super 7 with the early (type 1) clutch. (I also have a later version but that is a longer story!)

I have a number of questions, all related.

1. Are there drawings available for this series of the clutch? (I only have drawings of the type 2 clutch)

2. I want to replace the segmented belt currently installed with a standard belt (because the belt slips and precludes use of the outer two sets of pulleys (it's too big!)). Is there an easy way to achieve this without dismantling the entire clutch assembly?

3. Any real pitfalls at the headstock ?

4. Finally, The motor drive guard backplate is attached by a 1/4" BSF bolt onto the end of the swing head pivot shaft… but this shaft floats. I assume that it shouldn't – but cannot see how it is fixed in position.

Thank you in anticpation of your patience and advice.

Liam

[Liam Scanlan 1Participant @liamscanlan1]

[ianjParticipant @ians]

Hi Liam.I have copies of early Myford clutch document. I have sent you a personal message.Ian

[KWILParticipant @kwil]

There should be a 1/4" BSF x 1/4" pointed grub screw holding the shaft located on the frame (the tail stock side).

[Liam Scanlan 1Participant @liamscanlan1]

Thanks Ian (replied!).

Thank you Kwil, I'll go and look for the grub screw.

Liam

[Liam Scanlan 1Participant @liamscanlan1]

Thanks to the information received here, I have now disassembled the clutch successfully – many thanks!

Now for the next question…

The clutch appears to have had a hard life,the bearings (3 needle roller, one caged ball) all need replacing (sigh) – I assume that there will be replacements available (somewhere) – any specs and/or detils of suppliers would be appreciated. I am assuming I'll have to get the bearings removed/replaced by a small engineering company.

I assume that parts will be impossible to obtain such that my biggest problem is that the push rod and adjusting screw have been badly damaged – to the extent that the adjusting screw is jammed in the push rod. Is it feasable for me to make replacements? (I do have the originals as patterns). Would i need to temper the steel after turning the parts?

Should I just fit a later clutch?

Once again, thanks in anticipation for any advice.

Liam

[RobboParticipant @robbo]

Liam,

You can fit the later type clutch, in fact I have done just that today on a Mk1 S7, but you will need the complete assembly, swing head and all, as you can't fit the new shaft into the old bearings – without a lot of engineering which leaves the old parts much weaker. You don't need the pulley, they are the same of course. The other thing is the belt guard cover won't close because the later clutch sticks out, you will have seen that on your later S7.

Phil

[Liam Scanlan 1Participant @liamscanlan1]

Thanks for the information, Phil.

It just so happens that I bought a Mark 2 clutch (complete assembly) and a replacement belt cover guard too a while ago as I suspected that it may be needed… looks like it will be. Is the newer clutch better/more reliable? Of course, knowing my luck – that'll be faulty too! (*Note: Liam's First Law: "If it cannot possibly go wrong. It will".)

I just wondered about the feasability of the repairs to the Mark 1. I like fixing things, hate throwing stuff away, and keeping things original always appeals.

I will probably fit the replacement clutch tomorrow – but would still like to repair the original – just because…

Thanks for all the help guys!

Liam

[RobboParticipant @robbo]

Later clutch should be more reliable (but the Mk1 is now 60 years old so can be forgiven).

A word of warning do NOT attempt to dismantle the new clutch without restraining clamps, the spring is unbelievably powerful, and the parts will fly across the room like a bullet – and if you are bending over it then it's 999.

No reason to not repair the old one if you can get/fabricate the parts. They can be a bit fussy on assembly, may take a few goes to get it just right.

Phil

[Brian WoodParticipant @brianwood45127]

Hello Liam,

I think I can still find the Myford instructions booklet on setting up the Mk 1 clutch if you need them, they came with the usual Myford drawings of the parts making it up

I also have few pieces from a dismantled Mk1 clutch which I can look out for you if that is helpful. Send me a PM if you want to follow that up. They were notoriously difficult to keep operational without constant adjustment and noted for rattling in use. the Mk2 is a far better job in every respect.

Take note of Robbo's warning about the spring, it is VERY strong and capable of real damage if released

Regards Brian.

[Liam Scanlan 1Participant @liamscanlan1]

Given all the advice gained so far, I will fit the mk2 to get the lathe back up and running and refurbish the mk1 at leisure. I have taken note the warnings about the mk2 clutch spring – as from the information I have, there is no need to touch the clutch plate to install a belt, so that comes as a relief.

I will refurbish the mk1 clutch – just because it 'matches' the lathe. I will need to replace all the bearings – so no big rush there!

Thanks again, Phil (Robbo) and Brian, I will PM you.

Liam

[Liam Scanlan 1Participant @liamscanlan1]

With great thanks to all of the help and information received, I have successfully managed to change to a mk2 clutch and install the belts OK.

The only problem I had was in adjusting the spindle bearings – I cannot shift either of the adjusting rings (using the correct Myford spanner with as much force as I can muster). There is no end play in the spindle and the original mark on the spindle aligns exactly with the split in the adjusting collar. Do I just leave well alone – or have I missed something fundamental?

Many thanks

Liam

[RobboParticipant @robbo]

Well if there's no end play and the preload is OK then I would leave it alone, at least until you have run it for a while, then check again for end play. The clearance on the front bronze bearing is minimal, ie lock it up tight and then slacken until the spindle just moves freely.

Both the locking rings are R/H thread, though I don't suppose you were trying to move them the wrong way. To adjust the bearing you need to slacken the outer one first, then tighten the inner to pull the spindle out of the bronze bush. To adjust the bearing pre-load then slacken the screw in the adjusting collar (at end of spindle) just enough to let the collar move,and then turn the collar clockwise – towards you- to increase the loading. But if there is no end play there is no need for this, as this is how end play is removed, and too much loading will soon wear out the bearings.

To set the front bearing, pull it back using the locking rings (sslacken off the inner and draw it back by tightening the outer until the spindle is just solid, don't overdo it, then turn back the rear collar by 1/4" and tighten up the front collar.

However, if ther is play in the front tapered bronze bearing (side play), then you will have to do this to pull ithe spindle back into the bearing.

I think you probably already know this, and I don't think you need to do it in this case. But there it is for other viewers.   And I hope I have got it right and it's comprehensible.

Phil

 

 

Edited By Robbo on 17/05/2013 14:23:55

Edited By Robbo on 17/05/2013 14:28:29

[Brian WoodParticipant @brianwood45127]

Hello Liam,

I endorse all that Robbo says, it is word for word the Myford procedure.

The bearing rings are supposed to be tight making up a 'solid' block of the two angular contact bearings held between them. The grip there is on the outer races. There is an oiling spacer ring between them that should have its gap in line with the oiling hipple above, but without opening up you won't know whether it is correctly aligned..

Check it again after some running and feel the front conical bearing housing in use to be sure it is not running overly warm and keep the oil cup serving the bearing well topped up. It may need adjustment after that.The spindle should be almost stiff to turn gripping the nose thread in your hand.

Regards Brian

[Liam Scanlan 1Participant @liamscanlan1]

Thanks both, (Robbo and Brian) for your very helpful advice. It is much appreciated and well noted. I will check as advised.

Many thanks

Liam

[RobboParticipant @robbo]

Brian,

So I have remembered correctly, this was as shown to me by Brian McKechnie at one of Myford's open days – also scraping in a new spindle to the bronze taper bearing – but I'm not good at that – Brian was a master scraper.

Phil

[JOHN FOWLER 4Participant @johnfowler4]

Hello, ive just purchased a myford super 7 series 1.

And on inspection ive noticed that the clutch is cracked.

And a piece is missing off the clucth cover.

Has anyone got any mk1 clutch spares i could purchase?

thanks

John

[Brian WoodParticipant @brianwood45127]

Hello John,

I have a Mk1 horseshoe [the internal expanding piece] and the matching 4 step pulley making up the gripping parts of the clutch. I also have a new ball race and oilite bush but none of the actuating parts.

They are surplus to requirements.

Send me an email if you want to follow that up

wood [underscore] y [at] btinternet [dot] com] all in lower case and no spaces.

Regards Brian

[RobboParticipant @robbo]

John,

I think I have most parts for the Mk1 clutch, having replaced mine with the later one. By "clutch cover" assume you mean the cover over the drive belt from countershaft to headstock – don't have that.

You will find info on the Mk1 clutch in my albums "S7Mk1 clutch". The header says there are no photos in it, but there are 6. I deleted one photo and the system thought I'd done the lot.

Send me a PM for further info etc

Phil

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