myford pulleys slippage

[jae masonParticipant @jaemason79760]

hello there chaps

im having a bit of a problem with the pulleys on my headstock spindle slipping when i take the smallest of cuts on just ali

at first i thought it was the belt slipping …but no its the pulleys slipping on the shaft

ive had it apart looking for a grub screw to tighten up and there isnt one

ive added a vid of the problem of youtube that shows the exact problem

the link is in the description box

hopefully someone has had this and can help

thanks for any info

[jae masonParticipant @jaemason79760]

[jae masonParticipant @jaemason79760]

heres the link to the vid of my problem

Edited By JasonB on 23/10/2015 07:27:38

[John HaineParticipant @johnhaine32865]

Which pulleys on which shaft?

[Swarf, Mostly!Participant @swarfmostly]

Hi there, Jae,

Have a look at the large gear-wheel attached to the mandrel (aka spindle or shaft). On the right-hand side there's an allen screw with a hexagon socket head. On the left-hand side, there's a segment of gear teeth held by the other end of that screw.

Slacken the screw and slide the toothy bit down into engagement with the smaller gear on the end of the pulley cone, thenm tighten the screw. (You might need to grind a bit of the allen key so it'll fit between the screw head and the headstock casting.)

That should cure your problem.

To engage the back-gear to get the set of slower speeds, dis-engage the toothy bit and lock it in the dis-engaged position, then raise the back-gear lever to mesh the back-gears.

Have a practice with the motor off before you try it for real.

Best regards,

Swarf, Mostly!

Edited By Swarf, Mostly! on 22/10/2015 21:11:05

[Alex CollinsParticipant @alexcollins55045]

You have 1/2 engaged the Back Gear.

Cog Behind the chuck has either a lever or a screw ( allen key ) you need to tighten​

[RobboParticipant @robbo]

To confirm what Swarf,Mostly! has said, here is the relevant section from the ML7 user handbook

[Andrew Moyes 1Participant @andrewmoyes1]

The aluminium pulley should be an interference fit on the small brass or bronze gear. Yours has come adrift which is not an uncommon occurrence. I suggest you strip it all down, clean the pulley bore and the gear and fix the gear in position with Loctite retaining compound.. Or buy a replacement pulley assembly from Myford.

Andrew Moyes

[Andrew Moyes 1Participant @andrewmoyes1]

PS This page from the Myford website

**LINK**

shows the complete 'Vee cone pulley assembly 74/1234'. Immediately below it is the 'Geared bush 70/1229' showing the extension which should be a press fit in the pulley.

[davebParticipant @daveb17630]

Posted by Andrew Moyes 1 on 22/10/2015 22:19:44:

The aluminium pulley should be an interference fit on the small brass or bronze gear. Yours has come adrift which is not an uncommon occurrence. I suggest you strip it all down, clean the pulley bore and the gear and fix the gear in position with Loctite retaining compound.. Or buy a replacement pulley assembly from Myford.

Andrew Moyes

Agreed. It is clear that the pulley is slipping on the bronze sleeve. Loctite as suggested above is the fix.

Dave

[steamdaveParticipant @steamdave]

Jae

You may benefit joining the yahoo group for Myford lathes. There is a wealth of knowledge on all models of their lathes.

https://groups.yahoo.com/neo/groups/myfordlathes/

Dave
The Emerald Isle

[Swarf, Mostly!Participant @swarfmostly]

Hi there, again, Jason,

My bad – I should have looked more closely at your video.

Whether you decide to repair your existing cone pulley assembly or buy a new one, in either case you're going to have to dismantle the head-stock.

I'd suggest a bit of research before you start – lots of us have trodden that path before you! In particular, remember to take care not to get the peelable shims mixed up when you remove and replace the bearing caps. Carefully note where they go and ensure that they go back in the right places.

Best regards,

Swarf, Mostly!

[jae masonParticipant @jaemason79760]

thanks for the answers chaps……….when i went out to use the machine this morning the problem was gone………then once it got hot it started sliping again………..ive had 2 answers which both make sense here………

one says that the pulleys are an interferance fit and are just plain slipping, this makes sense as they are ali and will expand more than the shaft which is steel…..this is why they might slip when it gets hot…………………

also someone has said that the back gear is half way engaged which would also make sense

im going to investigate both senarios on monday firstly trying to fiddle with the backgear on the bullwheel

if that doesnt work then it looks like it could be the interferance fit has had its day……

if this is the case would i be making a real mess of things if i just drill and tap one of the pulleys then tighten them down to the shaft with a 5mm grub screw…????

maybe someone out there has tried that in the past and it either works or causes more problems…????

thanks for taking the time to answer me here…..ide be lost without a bit of youse chaos knowledge

[jae masonParticipant @jaemason79760]

i meant to say….youse chaps knowledge..lol

[davebParticipant @daveb17630]

I doubt if a grub screw through the pulley would solve your problem, the bronze sleeve to which the pulley is attached is not very thick, would probably distort and bind when you attempted to use the backgear. If you are careful when you remove the bearing caps and make sure the shims do not get mixed up, it's not a major job to remove the spindle,clean the pulley and sleeve and Loctite them together.

Dave

[jae masonParticipant @jaemason79760]

sounds like you have had the bad luck of having to do it yourself in the past dave……..once i have a better look at this on monday you may well be hearing from me again…lol

[KWILParticipant @kwil]

Do not use a grub screw to secure the pulley to the shaft, that will mean you will not be able to use the back gear ever. Take the sensible route and loctite the "lost" interference fit. Not difficult or time consuming.

[jae masonParticipant @jaemason79760]

i havent had a look at either options yet as it the weekend but the more i think about it the more im beggining to think it will need locktighting rather than it being the backgear half engaged

reason for this is that the problem gets worse the hotter the lathe gets

this is obviously the ali pulleys expanding more than the steel shaft once hot which allows them to turn on it….grrrrr

could anybody on here leave me a link on how to dismantle the sharf and remove these pulleys to locktight them…?????

thanks for all your help

[Howard LewisParticipant @howardlewis46836]

Its 12 years since I had a ML7 so my memory may well need correcting.

Remove the Chuck.

Remove the bearing caps, keeping the shims with caps as already said.

Lift out the mandrel., and start to strip off everything from the back (away from the Chuck) end, until the Pulley and Bush are off.

Separate the Bush and Pulley, clean both to remove any debris and greasy deposits, and apply Loctite and reassemble. Allow the Loctite to cure for at least 30 minutes before use, (preferably 24 hours)

To aid strip and reassembly, it may be worth heating the pulley in boiling water. For reassembly, with Pulley hot and dry, and Bush cold and dry, apply the Loctite. The higher temperature will increase the clearance for the Loctite, and help the Loctite to cure more quickly.

As they say in Haynes Manuals "Reassembly is the reverse of the above", but you may need to reset the thrust bearing to minimise end float.

To all Myford users, if my memory is faulty. Please correct me.

Howard

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