Myford super 7

[Michael FarmerParticipant @michaelfarmer99890]

Hi all

This my first post, hope I'm asking in the right place. I've just bought a Myford Super 7, the clutch was out of adjustment. With help from previous posts on this it's now working, although there is some drag, it's the early type that you adjust my removing a lock Allen Key then adjust the underlying Allen key. My question is does this type clutch need lubrication, the only reference l can find is lubrication to the cone type of clutch which is fitted to later models with the clutch at drive pulley end, whereas my lathe 1963 vintage the clutch is fitted at the lever operating end. Looking at the drawing and description it's more of a drum than a cone.

Michael

[Michael FarmerParticipant @michaelfarmer99890]

Clutch lubrication?

[David Taylor 4Participant @davidtaylor4]

Hi Micheal,

I have a '63 vintage Super 7 with cone clutch and I lubricate it with a shot of machine oil now and again. If you have drag probably the clearance when dis- engaged needs to be increased a little.

I have had the machine from new with no clutch troubles, in fact no troubles at all. A fine machine.

Dave Taylor.

[Michael FarmerParticipant @michaelfarmer99890]

Hi Dave

Thanks for the reply. Is your clutch fitted at the input pulley end or at the operating lever end? If your adjustment is at the input end the oiling is clearly mentioned in the manual. On my lathe you adjust the clutch by removing a locking allen screw, which reveals the adjusting Allen screw beneath. I only know all this from a previous thread on this forum, I'll try and post a link. Although this previous thread was helpful with the adjustment aspect, I must admit to getting confused as it went onto discussing clutches fitted to other models, some of which have friction material similar to that fitted to mopeds! Hence do i lubricate it or not? When you say a "few drops of oil" presumably this is applied through the hole in the pulley?

Michael

[Rick Kirkland 1Participant @rickkirkland1]

Michael, the clutch on your super 7 is the front brake drum arrangement from a moped. two of the ML7's in my shop are fitted with the same unit, but in the countershaft primary drive pulley. Do NOT oil the shoes, after all, you wouldn't put oil on it if it were in it's normal position being used as a brake. First of all we need a little more clarification as to the problem. Is it clutch DRAG? which is slipping caused when the clutch is disengaged but not clear enough from the driven side, or is it clutch SLIP?, which is slippage caused by not enough engagement pressure when the clutch is engaged to drive.

[RobboParticipant @robbo]

Michael

You've set a conundrum and caused some confusion here. From your description of adjusting your lathe clutch it is what is unofficially known as the Mark 1, and the clutch is an expanding horseshoe in a drum machined into the inside of the countershaft pulley cluster. However, you say your lathe is a 1963 model, and Myford stopped fitting the Mk1 clutch in 1958, and moved to the one fitted in the countershaft pulley at the left hand end of the countershaft.

So Dave, with his 1963 lathe, is referring to the latter type. And Rick is now thinking its the ML7 type which fitted on the left hand end of the countershaft.

If you have dismantled and cleaned your Mk1 clutch and the actuating mechanism, then lubricate on reassembly so that the push rod especially moves cleanly, and lubricate the visible mechanism at the clutch operating lever end. A drop of oil "down the hole" before fitting the adjusting screw and the locking screw will lubricate the tapered end of the push rod and the sliding wedge which forces the horseshoe into contact with the drum. Other than that then just keep the countershaft bearing oil cups topped up.

The drag you mention could mean that you haven't cleaned the mechanism and its sticking, or you need a bit more clearance on the adjustment. The wedge on the push rod may have got a bit worn and be sticking.

This drawing may help with the diagnosis.

[Rick Kirkland 1Participant @rickkirkland1]

ahh, Robbo, it's THAT one! dug out my old S7 manual earlier and realised it must be. Picture here is worth more than a thousand words Hoping it helps sort the problem for MIchael. One thing I would add is that one of these I worked on was dragging due to a really stiff ball race in the pulley. Full of accumulated muck.

[Michael FarmerParticipant @michaelfarmer99890]

Hi Robbo

Thanks for the reply the drawing looks correct for my clutch, but haven't managed to strip it completely. My son was helping me with initial checking, he found the serial number SK67863 and from this decided it be 1963-66. at this time there was hardly any drive with the clutch slipping, with a bit of googling we found how to adjust it. The drive is now ok with no discernible slip. however there appears to be some drag with it disengaged ie it still tends turn the spindle, but its not with any great force. I have removed the input pulley slackened off the pinch-bolt collar removed 2 grub screws on the clutch housing, removed the collar at lever operating end along with the lever and , its operating shaft. I understand the shaft taps out towards the tailstock, but it appears that the clutch housing is solid to the shaft, there 1-2 mm end float on the shaft until it comes up against the bearing housing, i'm reluctant to hit harder, in case i've missed something. Also I've noticed that if I hold the clutch against the bearing housing and rotate the shaft the clutch is forced back by 1-2 mm which is the same as end float as above. With the lathe running the clutch lever gives a little shimmy now and then, with some vibration, i'm thinking its all linked in some way. I can only backout the adjustment screw not completely remove it, I wonder if this is the problem as you mention drops of oil before replacing it.

Michael

[Michael FarmerParticipant @michaelfarmer99890]

Success! After much head scratching the clutch is apart. The adjusting screw had formed a dome on its self where it acts on the operating shaft, only allowing partial removal, thus locking clutch to shaft when I tried to drive it out, after copious applications of penertration oil I was able to back it out enough to clear the shaft! Presumably your ment to be able to fit and remove the adjusting screw from the adjustment hole in the pully? Hopefully I've added a photo

Michael

[RobboParticipant @robbo]

That's right Michael. The adjusting screw is simply a grub screw with a rounded end  threaded through the push rod, and should be removable from either end. Your picture shows it sticking out of the 'bottom' end of the push rod, where it rests on the taper of the actuating shaft. You will have noticed that the adjusting screw has a smaller thread (1/4" BSF x 3/4" long) than the locking screw (5/16" BSF x 3/8" long).

Your lathe bed number is correct for 1963, so you must have a modified lathe. Probably had some bed damage to the original and a used bed as a replacement. With old machinery you need a very open mind!

Your picture doesn't show the whole push rod, it should look like this:

Edited By Robbo on 19/05/2018 00:21:44

[DMRParticipant @dmr]

Michael,

The last S7 to have the "early" expanding clutch was SK 8127 made in June 1958 so your 1964 (It is) bed has been married to an early clutch at some time in the past.

I no longer have an early clutch but the shaft end float you describe should not exist. Do you have the red fibre thrust washers (2 off towards each shaft end) shown as item 4 in Robbo's part diagram? They were about 1mm thick each and would account for the float. As to the drag, the clutch ring should be free inside the pulley in its relaxed state while you have it apart, and it sounds like you were trying to remove the adjusting screw with the clutch engaged which is wrong. The adjusting screw should be domed where it meets the taper slot in the Actuating Bar. I have the early manual pages for setting the clutch which I can e-mail if you want them.

Dennis

Robbo beat me with some of this

Edited By DMR on 19/05/2018 01:20:13

Edited By DMR on 19/05/2018 01:22:31

[Michael FarmerParticipant @michaelfarmer99890]

Dennis thanks for that, I would appreciate the drawing and setting instructions. OK the adjuster should be domed, that makes sense but should it be turned down at the tip so it could be threaded all the way out? The fibre thrust washers are missing. The adjuster looks hand made as the slot is not exactly central.

I was feeling my way through removing the shaft, it was after a couple of of attempts that l decided to remove the counter shaft assembly complete with the pivoting mountings, as I thought I would have to resort to pressing the shaft out. Whether it was the oil freeing things up or turning the unit over or gradual progress of backing out the adjuster, l was able firstly to remove the operating shaft then backing the screw out to clear the shaft. So the clutch could not have been engaged.

Michael

[DMRParticipant @dmr]

Michael, I have sent you a PM with my e-mail address.

Dennis

[Michael FarmerParticipant @michaelfarmer99890]

Robbo…. thanks for confirming my thoughts on the adjusting screw, I will clean up enough to Thread it out into the pulley, leaving the tip untouched as hopefully it's work hardend to a degree.

I've taken advise from DMR namely assemble the clutch body, disc and pulley onto the shaft to check that it runs free with no drag, I'm pleased to announce it runs free with no sign of the drag that was evident before the strip. There was no particular wear or corrosion so it's a bit of a mystery, the clutch disc had very sharp 90 degree edges so I dressed these to reduce the risk of Chipping. I also dressed the witness marks on the pushrod (very slight metal displacement) the worst area of corrosion was on the operating shaft, the portion that's exposed, polished it up with very fine emery to make it silky smooth in operation. One of the 2 trunions was a very tight fit on the thrust bearing (beyond interference) resulting it only engaging onto the bearing by a mill or so, indeed it had spun off at some time, this would have caused an unbalanced force on the mechanisum and perhaps contributing to the drag. So all I have to do is to build it back into the lathe! After sourcing the thrust washers and new belts.

The back gear cluster has 1 tooth missing I don't need these low speeds at present but might replace it, as I need to replace belts.

Would it be to much or a risk using the back gear with a missing tooth?

Michael

[RobboParticipant @robbo]

Michael

It's been quiet while I've been absent! I thought you would have a lot of posts advising the use of link belts instead of V, so obviating the need to remove the spindle. Link belts are very popular with some members! I did find that a link made the running smoother between the motor and countershaft, but have had problems with slippage using one between countershaft and spindle.

As a regular user of backgear I wouldn't use it with a missing tooth, though presumably its on the 53 tooth cog which meshes with the 20 Tooth on the spindle pulley, so it will probably run over OK.

If you want a 17/53 tooth backgear, send me a message, I've found one in my box of old Myford bits. Postage in UK is a "small parcel" so £3 – 5.

[Michael FarmerParticipant @michaelfarmer99890]

Robbo

Thanks for the offer, I've already replaced the gear

Michael

[RobboParticipant @robbo]

When you do come to use the backgear, you can do so with complete peace of mind

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