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Myford ML7 Back Gear

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Steve Gibson27/04/2014 22:12:22
14 forum posts
1 photos

I've just purchased my first lathe, a Myford ML7.

It's a 1972 judging from the serial number, it has been used sparingly in a college from new and they have been turning wood on it judging by the sawdust in all the cavities.

It was 3 phase, so I am just putting on a single phase motor and I haven't yet ran it.

One thing I have noticed is that when I mesh the back gear to the chuck spindle it seem to lock the spindle, however when the back gear isn't meshed both the back gear and spindle spin freely. Is this normal as I can get my head around why 2 free spinning gears wont move when they are meshed?

Thanks

YAK27/04/2014 23:40:35
58 forum posts
2 photos

Hi Steve, it's something to do with the mainshaft. The pulleys for the belt has a phosphur bronze bush through it which seizes to the mainshaft. There is a oil nipple but it gets overlooked. Go to Myford Ltd and look at the diagrams.

Terry.

_Paul_27/04/2014 23:41:52
avatar
543 forum posts
31 photos

For the back gear to work you have to raise the front lever just behind the chuck this engages the backgear layshaft before it will work you then also have to release the little "dog" on the bull gear to disengage the direct drive have a look here for a reasonable explanation.

how the backgears on the ML7 work.

Jon Gibbs28/04/2014 09:05:33
739 forum posts

I suspect Paul is right. Have you remembered to disengage the bull-gear.

Unless you already have a suitable key you need to grind down the short end of a standard allen key to get at that locking screw.

You will need to check the size. Mine's an old imperial ML7 from 1950 and I suspect that yours might have metric allen screws as I remember reading somewhere about them changing over near to the end of production.

HTH

Jon

Kevin F02/07/2017 14:16:20
96 forum posts
24 photos

I've just purchased and ML7 and it will only run in back gear ? I've removed the wedge and reinserted the wedge and it doesn't matter , I still can access the higher speeds , any suggestions ?

Kevin F02/07/2017 15:07:48
96 forum posts
24 photos
Posted by Kevin F on 02/07/2017 14:16:20:

I've just purchased a ML7 and it will only run in back gear ? I've removed the wedge and reinserted the wedge and it doesn't matter , I still can't access the higher speeds , any suggestions ?

 

Edited By Kevin F on 02/07/2017 15:09:38

Edited By Kevin F on 02/07/2017 15:10:31

Kevin F02/07/2017 15:08:32
96 forum posts
24 photos

Duplicate post ( sorry )

Edited By Kevin F on 02/07/2017 15:11:21

Jon Gibbs02/07/2017 15:39:57
739 forum posts

You say you've disengaged the wedge (I assume you mean the toothed key on the bull wheel - see the socket head capscrew on the larger of the two gears on the main spindle labelled 1)

...but have you lowered the lever that controls the backgear cluster (4 &5) underneath the spindle nose? (the lever with the black knob in the bottom right hand corner of the picture)

HTH

Jon

Kevin F02/07/2017 17:16:33
96 forum posts
24 photos

Hi Jon , yep I've removed the socket cap Allen key and the toothed key , I've also lowered the lever which engages the back gear , I've switched on the lathe and it spins faster but as soon as you go and take a cut the 3 jaw chuck stops spinning but the headstock shaft still spins at the same speed .

I've put a cut on in back gear and it takes a sizeable cut no problem ,for info I'm not trying take a big cut at high speed and the material is aluminium 60826 .

Bazyle02/07/2017 17:26:58
avatar
5391 forum posts
206 photos

You don't remove the socket head screw, you loosen it, slide the 'wedge' in towards the centre to engage the teeth ( see the link given above) then tighten it.

What you have at the moment is just the friction on the mandrel from the oil pulling the bull wheel round while it has no load.

Jon Gibbs02/07/2017 20:06:36
739 forum posts

+1 for Bazyle's comment.

The choices are,

  1. toothed key engaged with bronze gear teeth and the lever in the lower position (lower gear cluster in the disengaged position) - (direct drive).
  2. toothed key disengaged from bronze gear teeth and lever in the upper position (lower gear cluster engaged with the bull gear and the bronze gear on pulley cluster) - (back-gears).

In direct drive the pulley is effectively locked with the larger drive gear using the toothed key.

In back gears, the bronze gear attached to the pulley cluster is loose on the main lathe shaft and meshes with the larger gear on the lower cluster, which is connected to the smaller gear on the lower cluster, which in-turn drives the upper large gear (bull gear) which is connected to the main lathe shaft. (Remember to oil the pulley on the main lathe shaft with Nuto 32 in back-gears).

If it's still slipping in direct drive then you might wish to check out this thread http://www.model-engineer.co.uk/forums/postings.asp?th=109042

Hope this helps

Jon

Edited By Jon Gibbs on 02/07/2017 20:17:55

Kevin F02/07/2017 22:57:20
96 forum posts
24 photos
Posted by Bazyle on 02/07/2017 17:26:58:

You don't remove the socket head screw, you loosen it, slide the 'wedge' in towards the centre to engage the teeth ( see the link given above) then tighten it.

What you have at the moment is just the friction on the mandrel from the oil pulling the bull wheel round while it has no load.

Thanks Bazyle , I've had a look and followed your explanation and I can now select the high speed range on my ML7 , it's simple when you know how , I just couldn't figure it out at the time !

Thanks Jon for taking the time to reply , I've read your link you posted , I've not used the lathe in anger yet ,so we'll await to see how it performs .

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