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ML7 left to run for 72hrs accidentally - what to check?

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William Ayerst27/01/2021 22:28:31
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98 forum posts

An unfortunate set of circumstances meant that my ML7 was accidentally turned on at the weekend and has been running since. It has been kept well lubricated before this incident and was running without anything on the spindle.

I turned it off as soon as I noticed and did a quick check - the oilers are empty, but there doesn't appear to be any play in the main spindle. The lathe itself was not hot, although the motor (Metro-Vick original?) was. No bad smells or obvious problems, but suddenly, I'm worried about everything - is this a new issue, or is this just manifested? Either way:

  • The belt from the motor to countershaft is a little frayed around the edges
  • There were a few black oil drips underneath the lead screw gears in the drip tray, and kept finding little amounts of the same in areas of the headstock - including the oil nipple for the countershaft.
  • The countershaft itself has a good deal of resistance to turning - i.e. there is no appreciable difference in difficulty turning it with or without the eccentric lever engaged whilst the lathe is middle gear that said, my thoughts were that if the countershaft if anything should be loose rather than tight if it was effected by this extended running period and I can't remember if I ever checked it.

Is there anything else I should be checking or doing (other than obviously taking measures to ensure this doesn't happen again!)

Many thanks!

Edited By William Ayerst on 27/01/2021 22:40:47

JohnF27/01/2021 23:35:19
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1049 forum posts
158 photos

William, never heard of it before and admittedly not an ideal thing to do but you seem to have checked everything you can and no ill effects so stop worrying !

Although the main bearing oil cups were empty, when there is no load on the spindle it will retain and oil film and if this had broken down assuming your machine has the white metal bearings they would have "run" and you could not miss this. Hot motor - only to be expected but clearly OK - no bad smells.

It really goes to show the longevity built into these machines

John

William Ayerst28/01/2021 09:01:11
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98 forum posts

Thanks John - I guess the only thing that feels a bit strange is the stiffness of the counter shaft, should it have some resistance or should it be easy to spin?

Brian Wood28/01/2021 09:21:06
2334 forum posts
37 photos

William,

I think the countershsft bearings will be showing up a lack of lubrication as a result of the prolonged running, other than that the lathe itself has come through with everything operational as it should.

So, a bit of oil where it is needed and away you go again

Regards

Brian

larry phelan 128/01/2021 09:35:18
944 forum posts
14 photos

Your electric meter ???????

Just asking !cheeky

Swarf, Mostly!28/01/2021 09:53:46
565 forum posts
47 photos

Hi there, William,

I hope that your ML7 has not suffered any irreparable damage.

It sounds as though you need to install a motor starter that incorporates no-volt-release.

Best regards,

Swarf, Mostly!

Oldiron28/01/2021 10:10:36
722 forum posts
23 photos

Would be interested to know how it was left running for that long. I hope it has no detrimental long term effects.

regards

Hollowpoint28/01/2021 10:51:03
402 forum posts
51 photos
Posted by Tony Wright 1 on 28/01/2021 10:06:11:

Just for fun how many revolutions do you estimate it ran ? 😂

3 days = 4320 minutes

Typical lathe motor runs at 1450rpm

1450 x 4320 = 6,264,000

😳

J Hancock28/01/2021 11:11:40
539 forum posts

Not to worry, the national debt increased by approx £360,000,000 over that period of time.

Pete Rimmer28/01/2021 11:43:37
912 forum posts
56 photos

I would not worry overly much. If any of the bearings had suffered lubrication failure you would have come back to a seized spindle or smouldering mess.

All I'd expect is a little bit extra normal wear. Not so much of that either since plain bearings are happier once warmed up a bit.

ega28/01/2021 11:55:28
1999 forum posts
166 photos

Would some moly benefit the counter shaft bearings?

Ady128/01/2021 13:32:05
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4228 forum posts
593 photos

No load running so it should be fine after a pint of refreshing lube

William Ayerst28/01/2021 13:34:36
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98 forum posts

Moly?

I'm happy that no major harm done - if it's been used for an hour a week since it was built (1952) that little escapade has only added half a percent of the total running time. Hopefully!

A no-volt release sounds like a perfect plan, as well as a start/stop that's not attached to the wall socket. I have a modern power cable, but no control box. Do you have any recommendations?

What happened was, I was working around the house and accidentally tripped the breaker for the workshop by nudging a box in the under-stairs cupboard. After some time went to the garage to get tools to cut some firewood - after messing around with a regular saw, I decided to use my chopsaw - which didn't work. I assumed it was broken. I then tried the lights, and they didn't work. And then tried the lamp over the lathe, which also failed. I swapped plugs around and inadvertently plugged the lathe into the lamp socket (which was turned on at the wall, but with the lamp switch itself turned off and the power still cut) and vice versa.

When the power came back on after I reset the breaker, instead of power being supplied to the turned-off light, it got supplied to the lathe!

Since I've now got all the easily removable parts off to transport the lathe (another story!) I wonder if it might be a good opportunity to give it a clean. i.e. the lead screw and gears inside the headstock are a bit grimy - is it a good idea? I'm assuming white spirit and a soft brush, and then a reapplication of the relevant oil/fluid once dry?

J Hancock28/01/2021 14:06:01
539 forum posts

One vital bit of information missing.

Did you leave the lathe with the drive belt tensioned (bad) or 'loose '(good). ?

That , may have saved your headstock bearings.

ega28/01/2021 14:55:02
1999 forum posts
166 photos

Not ecstasy but molybdenum disulphide.

NB my question mark as I don't know the composition of ML7 countershaft bearings.

Tony Pratt 128/01/2021 14:58:45
1413 forum posts
6 photos
Posted by ega on 28/01/2021 14:55:02:

Not ecstasy but molybdenum disulphide.

NB my question mark as I don't know the composition of ML7 countershaft bearings.

Original countershaft bearings are Phosphor Bronze.

Tony

Alan Donovan28/01/2021 15:50:40
34 forum posts
24 photos

Hi William.

My view would be that 72 hours of 'no load' running on a Myford is not really a problem, especially as you normally keep it well lubricated. The key thing here is that it was 'no load' running. These machines suffer much worse abuse in industry and survive.

Tony Pratt 1 mentioned that the countershaft bearings were phosphor bronze, that is correct but the original fit were sintered bronze bearings (which are porous to retain some of the oil) manufactured by 'Oilite'. A 'trawl' of the internet suggests that these bearings (in imperial sizes) are still available, should they be needed.

Best regards Alan.

Bazyle28/01/2021 19:52:18
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5780 forum posts
216 photos

In theory a smart meter monitor display would alert you to this sort of thing.

Chris Gunn28/01/2021 22:21:21
356 forum posts
24 photos

William, it sounds that it could be unlikely that this could happen again. Just in case you could feed the lathe through a timer with just the off flag set at the latest time you are likely to need it. the timer will switch it off.

I adopted this for my compressor, I used to switch it on, and if it was not actually running. i would head inside leaving it on. Later in the evening the lights would slightly flicker when it started up again. The problem was solved by the timer.

Chris Gunn

not done it yet28/01/2021 23:00:46
5609 forum posts
20 photos

The problem was solved by the timer.

But do buy a substantial timer. The lesser ones will fail with fairly low inductive loads, even though they will cope with 3kW resistive.

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