Stuck clutch - Mk2 Super 7

I just got my new Super 7 home but can't get the clutch to disengage, The Adjusting screw is way too far out but I can't get it to screw back in . . . I don't want to snap it.

Is there any chance I have forgotten to un-tighten something? Otherwise I'm going to be trying WD40 and heat for a while....

Thanks for any tips...

i think the clutch has to be engaged when making the adjustment - so that is the clutch lever towards the left - in towards the clutch mechanism

i think ..................

try it

Z

Jack,

On no account remove the nut off the end. It is in about the right place and the steel drive plate behind it seems to have some how got itself screwed into the pushrod.

First off, search this site for the previous thread as follows:-

myford super 7 clutch By terry callaghan. Just type into the search box Myford and leave the All Topics as is, and it's on page 4.

On no account attempt to release the pushrod entirely as there is a very powerful long spring in there. If you do and don't hurt yourself in the process, you are never likely to get it back together again! The jig to do it is large.

Please confirm that your clutch operating lever is NOT all floppy; that it has a spring action, and as you see it the clutch is simply not releasing. It would appear on first sight that the cone has somehow spun up the thread and was not lock nutted correctly - by the nut on the end. You need to turn the cone clutch plate (brass) and the drive plate (the steel circular-looking nut) outboard of it TOGETHER along the threaded push rod to about the position of the nut. The drive plate and the cone are keyed together, on no account try to move them independently.

Do you have a S7 Manual? Please read up all you can on previous threads on this and other sites before you do anything. As you seem to have just bought the machine, there may be a more sinister reason for your situation. Tread carefully. The spring inside the mechanism can be very dangerous if it gets out!

Dennis

It looks to me as though someone has deliberately screwed the adjuster rod up tight so that the clutch is solid, for whatever reason. Maybe they dismantled it and re-assembled it incorrectly - there are small parts inside the handle end which could be easy to lose. There should not be as much screw visible outside the drive plate.

I too have warned against dismantling and letting the spring escape, it is powerful, having said that I have dismantled one at home having taken precautions to catch the spring. It can be re-assembled using home made jigs.

Follow the advice from Dennis and see how you get on.

Phil

It is very possible I did this myself although I can't remember I thought the clutch was working when I got it, but at that time I didn't know the difference between clutch and belt leaver... so maybe not.

I had to dismantle the lathe a bit to get it home - I'm weak. At first I thought about taking the clutch and spindle out to avoid cutting the drive belt, but decided against that approach quite early on (luckily! but maybe not before I screwed the adjuster for some mad reason); instead Icut the belt and took the whole motor/clutch assy off.

Now I have it home, I put it all back together but the clutch leaver was completely floppy. I read the manual, and decided the clutch adjustment is wrong. I couldn't screw in the adjustment without the screwdriver failing, so thought I'd take it all apart to get better grip.

So now I have the clutch assy out of the machine, with the balls and spring etc safe ... somewhere.

The internals were covered in very old, thick, sticky grease.

That screw is still solid. I'm filling it up with Super Strong DP-60 (WD 40 substutute from the pound shop) which may give me a lubrication challenge if I solve the current issue. If that doesn't work, then I'll be heating the spindle a bit,

This is on the assumption that the only thing I should be doing is screwing that adjustment screw clockwise, into the clutch cone.

Thanks for the warning about the bit spring! I now fully appreciate that I should avoid total dismantle.

If you have not undone the screw yet the powerful spring is still to come and is most likely loading the clutch making the screw hard to move, be careful!

The spring may be coil bound which is why the assembly is tight now.

Mike

Edited By Michael Poole on 31/12/2013 12:06:48

Warm heat and penetrating oil doesn't make any difference. I'll try another day but after that the only option I can see is to try and split the drive plate off? Dremel then cold chisel, trying to avoid damage to the brass clutch plate and the push rod thread, and trying to avoid the push rod ejecting like a bullet.

I can then confirm Eddy Spriggs' method of reassembly

Edited By Jack Hobson 1 on 31/12/2013 14:10:49

Hello Jack,

This is what a correctly set clutch should look like. Your cap screws are missing which might explain it's position and stuck condition. The screws are 3/16" BSF [32 tpi] which 3/8" thread under the head, you can see how short they are from the one I have stuck on with blue tack

Regards Brian

Try locking two nuts together on the exposed thread with a gap to the driver plate, a nut can be borrowed from elsewhere on the machine, then screw the thread in to relieve the pressure. If this does not work something will have to be sacrificed. A nut could be welded on the end of the thread but this will likely render the rod unfit for further use, these are around £25 from myford. If the threaded rod is destroyed I think I would drill it out but this will result in the rod and spring firing out like a bullet, destroying the drive plate will cost about £17 the bronze plate is about £80. The main problem is to apply enough torque to the push rod to screw it back through the drive plate. If the assembly is off the machine try holding the thread in copper soft jaws in a vice then turn the pulley and clutch assembly by hand.

Mike

I don't understand this. The penetrating oil now flow right through. I made a c-spanner to turn the brass clutch plate but it won't budge even under a hammer. Cutting the drive plate is all I can think of... save that job for next year.

Jack,

Before you do anything that is not easily reversed e.g. cutting the drive plate or things like that I suggest that you contact Darren Boden an ex Myford lathe fitter who offers a Myford overhaul service. He may be prepared to give an opinion on how to resolve your problem or give you a quote for doing the job. His email address is [email protected] Tel 07790364189.

Have you examined the cross sectional drawing in the myford manual? Copies are posted in various places on the internet. The drive plate is keyed to the end of the shaft, try to avoid damage to this, they are nearly £100. The two nuts trick is a common way to remove studs without damaging them. Simply get two nuts and thread them both onto the push rod and using two spanners turn them to lock against each other, they will then be tight on the stud and the stud can be turned to screw into the drive plate, leave clearance for the rod to screw into the drive plate.

Mike

If using the 2 nuts locked trick, put one of them right at the end of the screwed rod and tighten the inner one up to it. Then whilst applying pressure with a spanner on the end nut, you can also give it a tap with a hammer, if the spring is coil bound this may release it, and as the nut is at the end it won't deform the thread.

Spares are so expensive I would think hard before using any destructive methods.

Phil

Jack,

I missed the point that you are missing the cap screws as Brian says (Sorry) but the drive plate is still keyed to the cone clutch and held there very firmly by the spring. I doubt it has ever worked right in your hands and the screws are missing because the previous owner had a go. You may have a situation whereby the drive plate and clutch have been driven in hard under power and the drive plate has hit the end of the thread on the pushrod - it is not threaded very far as there was no need for it, in which case you need to shift not only the end of thread but beat the spring as well! If you are still stuck then use the locknuting principle as above and put the drive plate in something very solid like a vice, stilson or mole grip and turn the outer nut as Phil says above. Marks on the nut are better than destroying it and don't bend the pushrod.

No more WD40 please. You don't want that in your bearings! The spring should not be coil bound as proper Myford used to compress it further in normal assembly without any binding.

Dennis

Jack,

I found the button to PM you. If you send me a reply with your e-mail, I can port the relevant pages from the manual to you.

Dennis

Hello again Jack,

My apologies, the sizes are very close and hard to sort on short lengths. The cap screws are 2BA x3/8", NOT 3/16" BSF in my earlier post.

Dennis I think has explained why it is so hard to unscrew, but rather than hold the drive plate with Stillsons, which will chew it up, a better alternative might be to make a pin spanner with two buttons to engage in the holes for the heads of the BA capscrews.

It could be held in contact by the end nut [1/4" BSF] using at least two spring washers to allow for thread space in unscrewing the drive plate. Clamp the clutch and motor belt to prevent turning and smack the end of your pin spanner anti clockwise with a hammer to shock the thread into release. Thereafter you can take things more gently and work the drive place back into position with the locked nuts approach that Michael Poole suggests.

I hope that and Dennis's information from the manual bring you some joy

Happy New Year

Brian.

I have misled you all. I took out the cap screws and have them safe. I took pleasure in being able to undo something Lathe has not been run without the cap screws.

I shall try the double nut trick but I have a real bad feeling that the torque required will exceed the strength of the push rod. If that snaps then I need a new push rod and still need to split the drive plate. Still, let's try...

The drive plate, clutch cone and main shaft are keyed together so are effectivly one part. The only part that can move is the push rod which as Dennis suggests has most likely screwed into the drive plate to the end of the thread and jammed. If enough torque cannot be applied to turn the push rod and it breaks then I think drilling the pushrod out will be the best solution, with care no other parts will be damaged and only a new pushrod required. Take precautions to control the sudden release of the rod and spring and make sure nobody is in the firing line.

Mike

Double nut trick worked eventyally!! Thanks everyone! Happy new year.

I have the exact same problem although I have now compounded it by breaking the split end of the push rod after applying some "torque"!! I will put a die on and rethread it and do the double nut method. It would be helpful for me to understand exactly what the thread is supposed to bear on in a correctly functioning clutch - is it ONLY the little hexagonal nut or does it mate with a female thread in the drive plate or the cone itself. Presumably the latter otherwise the instructions for adjustment would state clearly that the nut should be held in a spanner while turning the split end with a screw driver (ie "adjustment cannot be made with the nut removed". Thanks Adam