Super 7 Lathe Clutch, Countershaft or Pulley Wobble

[Oily RagParticipant @oilyrag]

Interesting problem that I have also had (poor finish and heavy chatter) albeit on a different make of machine. I'll come to that later though.

Firstly, congratulations to the OP for taking the trouble to video the problem, as they say a picture is worth a thousand words and a video is multiple pictures! Looking at this video I noticed several points which are worth further examination:-

1.The clutch/pulley wobble looks to be a bent layshaft as the pulley runs true when disengaged, suggesting that the bearing that the pulley runs on is true to the shaft, but only when the shaft is stationary = bent shaft?

2. Looking at the video at around 27 secs the layshaft pulleys appear to wobble, unfortunately the video skips over this part rather too quickly, viewed in slo-mo the wobble is more pronounced.

3. Then looking at the belt action between bull wheel and layshaft pulleys the belt appears to wander for depth (as in depth of engagement in the pulley vee) and in side to side movement. This comes at around 29secs into the video. Could this be belt flatting, hardening? which may be also causing an issue?

4. Finally the other point I noticed is the number 3 jaw of the chuck! At 43 – 47 seconds (around that area?) when the spindle is stopped and before the camera has refocused on the work I noticed that the #3 jaw is rounded off differently to the #2 jaw – is this damage or a mismatched set of jaws? If it is damage has the chuck been 'pranged'

The machine certainly looks to have been repaired, I agree a bent layshaft could be collateral damage from a 'topple' as mentioned by those above better acquainted with the Myford.

My problem was a dreadful chatter that would not respond to anything speed/feed or tool wise. I tracked it back to the layshaft bearing which had a cracked cage which I suspect was caused by the layshaft spindle being out of alignment through being unsupported at one end. New bearing, new drive belts (the old ones were hardened through age) cured the problem and resulted in a quiet and silky smooth machine.

Hope this helps,

Martin

[bernard towersParticipant @bernardtowers37738]

Ndiy, The grey bits are definitely Super7 I am standing beside one at the moment!

[Dave HalfordParticipant @davehalford22513]

At the very least it looks like this machine has been dismantled down to component pieces. It may not have been reassembled properly. I don't think it's run since it had the paint job.

[HopperParticipant @hopper]

Posted by mgnbuk on 02/01/2021 12:43:59:

So my best guess on that clutch wobble is that the intermediate shaft is bent, probably as a result of a backwards fall that appears to have been responsible for the damage that necessitated fitting the green replacement parts.

Nigel B.

^^^^^ This makes a lot of sense when looking at the parts that have been replaced with the aqua green components. Certainly would not contribute to the ultimate best possible turning finish but unlikely still to be the sole cause of the poor cutting going on currently.

One dodge might be to adjust the belt tensions as slack as possible without losing drive under normal conditions. This helps lessen transfer of pulley wobble from the countershaft to the headstock spindle.

[SteviegtrParticipant @steviegtr]

I have just looked at your video again & i am convinced that your ,,,, 1 , chuck is way out of alignment,, 2 there is play in the headstock bearings, which is easy to prove with a DTI on the workpiece. I would def say yes there is a problem with the countershaft spindle or bearings,

. Mine does not do that. But would not think it would transfer to the workpiece as bad as your video shows.

Steve.

[Peter SansomParticipant @petersansom44767]

Check the bearings in the clutch assembly, there are 2 Deep Groove shielded ball bearings (Imperial) RLS 5-ZZ (LJ5/8-ZZ) in the clutch pulley. Replacements are available from Bearing suppliers. I replaced these bearings due to Clutch noise 2 years ago. Remove the circluips and they can be pushed out fairly easily.

Additionally there are 2 Oilit bushes and 1 ball thrust bearing (Imperial series) that the main counter shaft runs in. Can supply the SKF part number fro this bearing tomorrow as I have 1 and the new oilit bushes sitting in a Workbench drawer waiting to be replaced.

Please note there is a spring inside the clutch assembly that care must be taken to disable. Find the instructions, there are videos on youtube.

Peter

[John StucksParticipant @johnstucks]

Hi, can anyone offer some advice on how to test/check the clutch plate, countershaft and countershaft bearings to see which one needs some work or replacing?

Also I’m researching how to setup or reset the headstock bearings but I’m finding I’m doing more reading on this topic and not finding much concrete instructional information. Like someone mentioned above, the manuals and books are a good read but dance around the point a little. They say a lot with out saying enough..!

Thanks,

John

[not done it yetParticipant @notdoneityet]

And I basically said ‘“If it ain’t broke, don’t fix it”. Why waste time on adjusting it if it doesn’t need it?

If I think I might have unwanted end-float, I set out to measure it so that I know whether it needs adjusting.

[Martin KyteParticipant @martinkyte99762]

As you say the wobble still exists when the spindle is not rotating I would aggree with many here on bent countershaft.

If you want to set up your headstock bearings this is the way that Myford used to do it.

regards Martin

1. Power Down

2. Remove all belt tension.

3. Remove Chuck

4. Rotate RH collar one complete turn. (top towards you).

5. Rotate LH collar one complete turn. (top towards you).

Spindle should be completely free of front bush.

6.Loosen allen screw on collar at end of spindle.

7. Using the Allen key tighten collar as tight at it will go by hand.

Inner tapered roller races are now locked together with correct pre-load.

8. Back off LH collar one complete turn + a bit (top away from you)

9. Rocking the spindle by holding the spindle nose tighten the RH collar by hand (top away from you).

10. When you feel resistance to movement stop.

11. Collar should be just tight enough that spindle can just be moved by hand holding the nose.

12. Do up the LH collar by hand (top towards you).

You should still feel resistance when turning the spindle by the nose.

13. With the crescent wrench on the LH collar tap the end smartly with a 12oz hammer.

The spindle should move forwards by a couple of tenths and be completely free running.

14. With the lathe running slowly (lowest direct speed) put the oil gun in the front oil cup and pump until oil issues from the front bearing.

[SteviegtrParticipant @steviegtr]

I have just had another look on youtube & there is quite a few good video's on the subject. Words are just words. A video explains & sinks in much better.

Steve.

[John StucksParticipant @johnstucks]

Totally agreed! I learn much better visually. I can find videos on the headstock, but not much on deciphering problems with the clutch plate, countershaft or countershaft bearings. Which parts to measure, how to find faults and possible misalignments/bends etc.

[Maurice TaylorParticipant @mauricetaylor82093]

Hi, have you tried cutting with the tool on center yet?

When I got my ML7 ,some of my cutting looked like yours, I made sure I had got EN1A steel to practice with . I’ve always used HSS tools I’d read that they are easier for beginners and old lathes.

Whenever my cutting looked like yours ,the tool was either too low or too high or it was not ground correctly.

Also the gib strips need to be setup. Try this before looking at more complicated things.

Once I’d done all this I got a good finish .

Maurice

[noel shelleyParticipant @noelshelley55608]

For the rear bearing setting collars a cheap ER32 C spanner with slight adjustment on a grinder will fit and make the job easier. Good Luck.

[John StucksParticipant @johnstucks]

Thanks again for all the suggestions. I’ve not yet got my 8mm tools (on order) so am not messing around with it all until ive got those, set the height and test cut.

Lots of people mention possible bend countershaft, but not sure how I can test for this. Same with a worn clutch plate, how is this tested.

Gib strip set up, is this just making sure they’re correctly right to allow movement of slides but no slack?

Thanks,

John

[Tim StevensParticipant @timstevens64731]

The countershaft should have no effect on the lathe's working – in fact, the countershaft need not be there at all – until you engage the back-gear for low speed drive. When the countershaft is turning – whether driven by the back-gear or turned manually – the shaft and the gears on it should run true, with no wobble, no up and down, and ideally no slack end to end. Or at least, very little. A shaft which does wobble is likely to be difficult to restore to perfection, but not too complicated to make new from scratch (except that you can't do it on your lathe – you ned a friendly and competent mate with his / her own kit). If only the back gear itself wobbles, on a true-running shaft, then the gear itself is at fault – but this is not likely in my limited experience – a damaged centre might be mendable by re-bushing it.

I cannot comment on the clutch plate issues, as I am not familiar with Myford practice. But, most clutch plates have a steel disc with either holes for inserts (often cork) or a rivetted (or bonded) sheet each side of the stuff that brake linings are made of. If the corks are worn level with the steel, or the facing is very thin or oil soaked, or distorted from heat, it will be obvious, but you usually need to dismantle to get a proper look at it.

Hope this helps – Tim

[noel shelleyParticipant @noelshelley55608]

Hi Tim , from your description of a clutch your a bike man ! The Myford cluch is, in this case a cone clutch. The back gear runs on the spindle or mandrel, NOT the counter shaft. Noel.

[Howard LewisParticipant @howardlewis46836]

Maybe a red Herring, but if the countershaft is bent, the only effect might be to cause the mandrel to rotate at an varying speed (varying angular velocity ) which could cause an inconsistent surface finish.

Once the OP has cutting tools which are sharp and set at centre height, that will be one variable eliminated, hopefully, and things may become a little clearer..

To get a good surface finish, it is necessary to learn how to set up the change gears a fine feed rate, or to rotate the Saddle travel handlewheel at a steady rate.

Lets see what transpires

Howard

[Tim StevensParticipant @timstevens64731]

Yes, Noel, I was understanding the term countershaft to mean the one that sits in the headstock under the output spindle. And the same applies to the clutch plate – as I now remind myself that the S7 had a cone clutch as distinct from a plate clutch, and therefore I guessed wrongly (silly me) that the S7 had a plate clutch (while the ML7 I know can have a cone). The term 'clutch plate' was used in comments by others, remember.

Just remind me, someone, what the proper term is for the shaft which is used for low ratios. It is part of a gearbox, and the normal name for a shaft which runs alongside the mainshaft and can be engaged or not is – guess what – a countershaft. Silly me, again.

Cheers, Tim

Edited By Tim Stevens on 04/01/2021 15:32:07

[Howard LewisParticipant @howardlewis46836]

"Couter shaft" brings to mind a shaft between the motor and the spindle, carrying pulleys, to provide a speed reduction.

The shaft within the headstock, carrying the back gears, which can be brought into mesh to provide greater speed reduction of the spindle, I would describe as the "back gear shaft".

"Clutchplate" conjures up an image of the centreplate in a vehicle, rather than a part of a cone clutch.

Mention of "corks", immediately pointed my mind towards motorcycles, although I have never been a biker.

Howard.

[Clive Brown 1Participant @clivebrown1]

Posted by Tim Stevens on 04/01/2021 15:29:55:

Just remind me, someone, what the proper term is for the shaft which is used for low ratios. It is part of a gearbox, and the normal name for a shaft which runs alongside the mainshaft and can be engaged or not is – guess what – a countershaft. Silly me, again.

Cheers, Tim

I'd call that a layshaft.

[Howard LewisParticipant @howardlewis46836]

Clive,

So would I

Howard

[John StucksParticipant @johnstucks]

Eagerly awaiting the 8mm tool so I can do some more testing in earnest. Should be later this week, royal mail dependant. John

[noel shelleyParticipant @noelshelley55608]

Hi Tim and all, In a vehicle gear box the first motion shaft carries the clutch, one end is often supported by the pilot bush in the flywheel. This is carried by a bearing in the front of the box, the other end is carried on a needle roller bearing in or on the main shaftT.he main shaft carries the the various gears all free to rotate and selected by the sliding sleeves and if your really lucky synchro cones, once locked to the main shaft power is then transmitted out the box.The main shaft bearing is in the back of the box. Along side the main shaft is the lay shaft carrying the lay cluster, a collection of gears machined out of one piece of steel. The lay cluster is rotated by the first motion shaft. This is a very basic description. Noel.

[HopperParticipant @hopper]

Motorbike gearbox secondary shafts are referred to as both layshaft and countershaft, depending on which factory workshop manual or parts book you take as gospel. Countershaft seems more common in recent years. So BSAs had layshafts, Hondas countershafts. Harleys have countershafts and have done so since day one so perhaps that is where it came from?

 

Edited By Hopper on 05/01/2021 01:59:52

[HopperParticipant @hopper]

Posted by John Stucks on 03/01/2021 20:34:27:

Thanks again for all the suggestions. I’ve not yet got my 8mm tools (on order) so am not messing around with it all until ive got those, set the height and test cut.

Lots of people mention possible bend countershaft, but not sure how I can test for this. Same with a worn clutch plate, how is this tested.

Gib strip set up, is this just making sure they’re correctly right to allow movement of slides but no slack?

Thanks,

John

Yes, set gibs for free movement but no slack.

Bent countershaft? Maybe. Maybe not. There is not much of a wobble there. My flogged out fixed ML7 pulley wobbles more than that, with no noticeable effect on finish of the job. Rubber belts, if new, are very flexible and forgiving if not run guitar-string tight.

And there is a pushrod up a hole in the middle of that counter shaft so if it were bent very much the pushrod would be binding.

You may just have a slack countershaft bearing. This is very common. To test that, loosen the belts and leave clutch engaged, grab the pulley and see if you can feel any up and down movement of the shaft in the shaft bearing on the H frame behind the clutch. Put your finger in there and feel for movement. Should be a thou or three there. If excessive, like 10 thou or more, you can press in a new Oilite standard sized sintered bushing with a nut and bolt and flat washers.

To check for bent shaft you would have to pull off the clutch then rotate the countershaft by hand with belts slack and observe the end of the shaft or clock it with a dial gauge. Myfords website has parts drawings of the clutch. Not sure, but it looks like you undo the small bolts and pull the actuator off the end of the clutch, and the spring/s and then maybe a circlip and the clutch body should slide off the shaft. Should be self evident from looking at it. Not particularly complex. Maybe someone on here with a S7 has done this job and can elucidate?

Edited By Hopper on 05/01/2021 02:12:44

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