Jammed Motor Pulley on shaft of Myford Super 7

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Jammed Motor Pulley on shaft of Myford Super 7

This topic has 31 replies, 9 voices, and was last updated 8 September 2014 at 14:03 by Gordon W.

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6 September 2014 at 19:54 #17501
Adam Harris
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@adamharris13683
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6 September 2014 at 19:54 #162848
Adam Harris
Participant
@adamharris13683
In order to service or replace the motor on a Super 7 (or indeed the belt guard back plate) it is necessary to remove the motor pulley before removing the motor and often the pulley is seized on so badly that judicious use of a standard 3 legged puller (judicious because the edge of the pulley would be damaged easily by the puller's 3 feet) is no good. What I think is needed is to fabricate a type of adjustable plate or square section triangle to fit behind the body of the pulley and to locate the puller feet onto that. Before I go any further, I wonder if anyone else has come up with an elegant solution to deal with this not infrequent problem on old Myford Super 7's…anyone?

Edited By Adam Harris on 06/09/2014 20:00:07

Edited By Adam Harris on 06/09/2014 20:00:33
6 September 2014 at 20:27 #162853
Michael Gilligan
Participant
@michaelgilligan61133
Adam,

It doesn't answer your question, but you might find this interesting …

When I removed the motor from the ML7-R, there was no key between the shaft and the pulley: The pulley was only retained by the grub screw; which had obviously been rattling in the [motor shaft] key slot and had bruised it quite badly.

That said; it did slide off O.K.

Generally … Your idea sounds good.

MichaelG.
6 September 2014 at 20:28 #162854
Adam Harris
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@adamharris13683
Or maybe cut some thick plate into a horse shoe shape with an outer diameter a bit greater than the outer pulley and in inner diameter a bit greater than the inner small pulley…
6 September 2014 at 20:40 #162855
Adam Harris
Participant
@adamharris13683
Interesting Michael – certainly testament to the ease with which the pulley can and does often jam onto the shaft. Annoying. I think I am going to cut some 5/16 plate I have lying around with a grinder into such a horse shoe shape tomorrow morning, although I do hate grinder noise from others on a Sunday morning!

Edited By Adam Harris on 06/09/2014 20:40:59
6 September 2014 at 20:49 #162856
john fletcher 1
Participant
@johnfletcher1
Over the past twenty years I have had reason to remove pulleys from several Myford super seven lathes motors and all have fixed by grub screws, not a key in sight. Once the grub screw is removed, all that is needed is a bit of careful persuasion using two pieces of flat steel or similar.Ted
6 September 2014 at 21:15 #162859
Michael Gilligan
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@michaelgilligan61133
Posted by john fletcher 1 on 06/09/2014 20:49:09:

Over the past twenty years I have had reason to remove pulleys from several Myford super seven lathes motors and all have fixed by grub screws, not a key in sight. Once the grub screw is removed, all that is needed is a bit of careful persuasion using two pieces of flat steel or similar.Ted

.

Thanks for that info. Ted

I had assumed mine was a "Friday afternoon job".

… Sounds like it's actually the infamous "Product Improvement".

MichaelG.
6 September 2014 at 21:26 #162860
speelwerk
Participant
@speelwerk
On the two I have both have a key in the motorshaft that is held in place with a grub screw. Niko.
6 September 2014 at 21:41 #162862
Adam Harris
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@adamharris13683
I also have 2 and both have keys with a grub screw pressing onto it.
6 September 2014 at 21:42 #162863
Adam Harris
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@adamharris13683
Actually I'm not sure that the grub screw presses onto the key , I will have to check that.
7 September 2014 at 01:47 #162876
Chris Trice
Participant
@christrice43267
Ditto. Grub screw onto the key in the shaft. The pulley is a good fit but usually comes off easily with a puller i.e. pulled off the shaft evenly.
7 September 2014 at 07:13 #162883
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Adam Harris on 06/09/2014 21:41:03:

I also have 2 and both have keys with a grub screw pressing onto it.

.

Yes, that's obviously how it was designed to work.

hence my sarcastic reference to "Product Improvement"

MichaelG.
7 September 2014 at 07:28 #162884
Nicholas Farr
Participant
@nicholasfarr14254
Hi, I'm not familier with Myford biuld practice, but in industry pulleys held with a grub screw often have one on top of the other whitch helps stop them from working loose. It is like double nutting a bolt/stud, may be worth checking.

Regards Nick.
7 September 2014 at 10:35 #162895
Chris Trice
Participant
@christrice43267
It’s poor practice to grub screw directly to a shaft. It raises a burr which can make disassembly difficult. The norm is to grubscrew where there’s a clearance or provide a flat/groove for the grub screw to contact. The alternative is to provide a pad made of softer material, usual brass or copper, to go under the grub screw.

Edited By Chris Trice on 07/09/2014 10:37:53
7 September 2014 at 12:14 #162900
Ian S C
Participant
@iansc
Take the grub screw right out, and check that there is not another grub screw down the hole.

Ian S C
7 September 2014 at 13:05 #162904
Michael Gilligan
Participant
@michaelgilligan61133
For info … [see my earlier post]

Here are some pics of the pulley and motor shaft from my recently purchased [secondhand] ML7-R

The damage on the motor shaft [and the consequential damage to the bore of the pulley] is obviously down to the absence of a key … but the scuffs and digs on the pulley suggest that it has been removed before; so I still don't know how it was originally assembled.

MichaelG.
7 September 2014 at 14:00 #162912
speelwerk
Participant
@speelwerk
Michael, as you can see in your pictures the grub screw sits almost on the edge of the key, which is missing in your pictures. When you tighten the screw you have to make sure the key is in the correct place under the grub screw and the pulley is lined-up accurate otherwise the pulley will work loose during use. Tightening the grub screw is much hampered by the belt gard back plate. Niko.

Edited By speelwerk on 07/09/2014 14:02:06
7 September 2014 at 15:32 #162923
Ian S C
Participant
@iansc
When a grub screw is used on top of a key, it should be fairly near the middle of it's length.

OT. On machinery that I'v been assisting in manufacturing (agricultural), we use two grub screws, one over the key, and the other at 90*.

Ian S C

Edited By Ian S C on 07/09/2014 15:34:40
7 September 2014 at 15:59 #162928
Michael Gilligan
Participant
@michaelgilligan61133
Posted by speelwerk on 07/09/2014 14:00:45:

Michael, as you can see in your pictures the grub screw sits almost on the edge of the key, which is missing in your pictures. < etc. >

.

Thanks, Niko

Yes, that's what I was pointing out …

What worried me was when Ted [john fletcher 1] indicated that he has seen several like that. … suggesting that it may have become "standard".

MichaelG.

Edited By Michael Gilligan on 07/09/2014 16:00:38
7 September 2014 at 18:11 #162946
speelwerk
Participant
@speelwerk
As far as I know they all should have a key held in place by the grub screw, but as Ian S C has pointed out placing it on the edge is not how it should be done and I can understand they get missing over time. You can improve it a little by rounding the underside of the key so you can push it further in the key way of the shaft. Niko.
7 September 2014 at 18:23 #162947
Chris Trice
Participant
@christrice43267
In my opinion, that’s been butchered by a previous owner who lost the key. I’d clean the shaft up with a file to lose the burrs and and then look at getting a replacement key. It would NOT have left Myford like that.
7 September 2014 at 18:25 #162948
Chris Trice
Participant
@christrice43267
… and the burring on the edge of the shaft slot is why you struggled to get the pulley off.
7 September 2014 at 19:02 #162953
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Chris Trice on 07/09/2014 18:23:51:
In my opinion, that's been butchered by a previous owner who lost the key. I'd clean the shaft up with a file to lose the burrs and and then look at getting a replacement key. It would NOT have left Myford like that.

.

Chris,

" I'd clean the shaft up with a file to lose the burrs "

That's exactly what I have just done … but it doesn't explain Ted's observation.

MichaelG.
7 September 2014 at 19:08 #162954
CotswoldsPhil
Participant
@cotswoldsphil
The pulley on the Super 7 (1972 vintage) I have has 2 grub screws – 1 clamping the key (which is present) and one at 90' bearing on the motor shaft, albeit with a little bruise to the shaft. However, I was able to pull the pulley off quite easily without any damage. Did the pulley design change over time? as you all seem to be talking about only one grub screw being present.

CotswoldsPhil
7 September 2014 at 19:29 #162958
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Michael Gilligan on 07/09/2014 19:02:02:

Chris,

" I'd clean the shaft up with a file to lose the burrs "

That's exactly what I have just done …

.

Unfortunately, it's not going to be a simple job after all

The motor shaft has cleaned-up nicely, but the hole in the pulley is bell-mouthed. presumably because it's been rattling … all very frustrating, but I shall probably leave it for now: I can re-bore and sleeve the pulley when I fit a 3-Phase motor.

MichaelG.
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