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Servicing a Myford 254

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Chris Pearson 102/05/2019 14:05:10
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I'd be most grateful for advice on a couple of matters in connexion with servicing a Myford 254 please. FWIW, mine is a 254+ Varispeed.

(1) I wish to remove and inspect the spindle - there is a hint of vibration and the oil in the headstock was not entirely clean. I cannot detect any play in it. Removal of the spindle may be fairly easy, but putting it back may be more difficult. Can anybody advise on, for example, whether any preload is required for the taper bearings.

(2) There is what looks like a small oil reservoir on top of the leadscrew nut. I don't think that it can be a reservoir because (a) there is no obvious way of filling it save for removing the apron, and (b) any oil would flow straight out.

If have a copy of the owner's manual, but was there ever such a thing as a service manual?

Many thanks in anticipation.

David George 102/05/2019 18:38:03
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794 forum posts
282 photos

Hi Chris welcome to the forum there are many Myford lathe owners on here and I am sure someone will help. Have you looked at the spares department on the Myford.co.uk web site. There are parts list and diagrams on there it may help with how the motor and guard etc are fitted.

David

lfoggy02/05/2019 20:12:42
51 forum posts
5 photos

I've got a 254 + purchased new in 1997. All I do is change the oil in the headstock, gearbox and saddle every year or so. My lathe is not a varispeed but I recently changed the motor to a three phase and fitted an inverter so I now have variable speed. This made it run a little smoother and the variable speed is very welcome.

Had a vibration issue once which I tracked down to a small granule of cast iron (presumably from the manufacturing process) inside the headstock which had become lodged in one of the gear teeth. This caused a vibration when running in back gear. That is the only problem I have ever had with it.

I've never had to do any servicing on the spindle bearings themselves. Are you sure your vibration is coming from the spindle bearings and not from elsewhere? Is the vibration present when you have the lathe in direct drive without the feed engaged? Have you checked that the drive pulley is properly coupled to the end of the spindle? This can come lose and vibrate.

Does your owners manual have the full exploded diagram of the headstock assembly? If you did want to dismantle it this would be useful. If you don't have this I can send it to you.

lfoggy02/05/2019 23:56:36
51 forum posts
5 photos

There is an oil bath in the apron that lubricates the power feed gears. There is a plug for draining the oil at the bottom of the apron and access to add oil at the top.

Hopper03/05/2019 06:54:19
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3611 forum posts
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Hi Chris and welcome to the forum. I assume (and I may be wrong of course) from your questions that you are more toward the novice end of the skill-levels scale. So you might be best to not go pulling the spindle and bearings out of your lathe at this stage. It's not really a beginner exercise.

Yes, being opposed taper rollers, they should have a bit of preload. Not sure on the specific Myford procedure but opposed taper rollers in general need to be adjusted so there is no discernible shake or movement and just perceptible drag when the spindle is spun by hand. (Remove any oil seals so false drag is not created.)

This is usually set with a threaded collar that tightens up against one of the bearings. Should be set after the lathe has been run for half an hour to get it up to operating temp.

If you are worried about corrosion or wear in the bearings, you should be able to feel this by rotating the spindle by hand. Any roughness felt indicates a bearing problem.

But your vibration as has been said is more likely to be created by something else in the drivetrain. Taper roller bearings are usually very long lived and problem free, if adjusted right and kept lubricated.

One big source of vibration on old machines is old drive belts. They go hard and if left unused for years develop set-in curves on the part that was around the pulley all that time. New V belt/s may be all you need. Buy good quality brand name from a reputable supplier, not the cheapies off t'interweb. I prefer the ones called "cogged V belt" that have a series of closely spaced notches around the inside, which lets the belt bend more easily around the small diameter pulleys found on most hobby lathes. Seems to smooth them right down.

Let us know how you go. It's a very nice machine you have there and should be a joy to use when set up right.

 

Edited By Hopper on 03/05/2019 06:57:12

Nigel Bennett03/05/2019 11:17:09
286 forum posts
6 photos

I've no knowledge of the Myford 254, but in the Boxford 280 manual I have it suggests very strongly that you don't faff about with the bearings, but leave it to their service department.

However, they say - if you must...

"Pre-load condition may be checked using the cord & spring balance method, when a steady pull in the region of 0,68kg (1.5lb) for new bearings or 0,34kg (0.75lb) for used bearings should be obtained, with the cord wrapped round the spindle nose and all gearing disconnected from the drive."

I imagine the two arrangements are very similar - adjustment by fine-pitched collars to set the preload.

I changed my spindle bearings on my Boxford, and it's not a task to be undertaken lightly.

Chris Pearson 103/05/2019 14:30:16
8 forum posts
1 photos
Posted by lfoggy on 02/05/2019 20:12:42:

I've never had to do any servicing on the spindle bearings themselves. Are you sure your vibration is coming from the spindle bearings and not from elsewhere? Is the vibration present when you have the lathe in direct drive without the feed engaged? Have you checked that the drive pulley is properly coupled to the end of the spindle? This can come lose and vibrate.

Does your owners manual have the full exploded diagram of the headstock assembly? If you did want to dismantle it this would be useful. If you don't have this I can send it to you.

Ifoggy, thank you for the response. Yes it is present in direct drive and absent with the belt removed - I have replaced the motor's bearings. Yes, pulley is tight.

Yes the manual has the exploded diagrams. There is no obvious means of adjustment.

Chris Pearson 103/05/2019 14:46:07
8 forum posts
1 photos
Posted by lfoggy on 02/05/2019 23:56:36:

There is an oil bath in the apron that lubricates the power feed gears. There is a plug for draining the oil at the bottom of the apron and access to add oil at the top.

Yes, thank you, I know about that, but why does the leadscrew nut have what looks like a reservoir? It cannot be one because the oil would simply run out. Odd!

20190503leadscrewnut.jpg

Chris Pearson 103/05/2019 14:53:18
8 forum posts
1 photos
Posted by Hopper on 03/05/2019 06:54:19:

Hi Chris and welcome to the forum. I assume (and I may be wrong of course) from your questions that you are more toward the novice end of the skill-levels scale. So you might be best to not go pulling the spindle and bearings out of your lathe at this stage. It's not really a beginner exercise. ...

But your vibration as has been said is more likely to be created by something else in the drivetrain. Taper roller bearings are usually very long lived and problem free, if adjusted right and kept lubricated. ...

One big source of vibration on old machines is old drive belts....

I have replaced a fair few bearings in my time. The worst one came out of a Jaguar's rear hub - the rollers looked more like gallstones.

Thank you for suggesting the drive belt - even though it looks fine, replacing it won't break the bank.

lfoggy04/05/2019 22:20:33
51 forum posts
5 photos

If the drive belt is too tight this can cause vibration as well. Maybe try loosening the belt?

Not sure what that recess in the lead screw nut is. To be honest I have never actually dismantled my apron. To lubricate the lead screw when screwcutting I just apply a very occasional squirt of oil direct to the lead screw.

Hope you get your lathe sorted. They are decent machines.

Chris Pearson 122/05/2019 21:42:56
8 forum posts
1 photos

Well, it's now in pieces and I shall be off to my usual bearing supplier tomorrow.

There is quite a bit of fine, and not so fine, swarf in the bottom of the headstock. It is mostly below the right hand bearing, which shows signs of wear, but it doesn't seem to be enough to account for the muck. There is no obvious damage or wear elsewhere.

Photos to follow.

Hopper24/05/2019 06:27:21
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3611 forum posts
72 photos

You'd have a lot of wear in a bearing to create swarf. Perhaps it's from gears? Or leftover from rough castings not cleaned up on manufacture as well as they could have been? But definitely should replace bearings anyhow now it's all apart.

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