Myford ML7 safe spindle speed

[Jolyon de FossardParticipant @jolyondefossard98326]

Hi,

I'm new here and am seeking some advice, please. I have just got a 1969 Myford ML7 which I am restoring. My main lathe is a Colchester Student which is great but a little big for some of the work I do. I read, however, that the ML7 maximum spindle speed is about 600rpm (Colchester runs to 1200). My L7 has White metal bearings.

I was wondering whether modern lubricants have enabled forum members to increase the spindle speed safely and if so, by how much ?

If not; could I add a Super 7 headstock or whuld that necessitate changing backgear/countershaft etc.

Apart from eBay can anyone recommend a place for Myford spares ? I need a few other things like a rack, some oilers and a leadscrew hand wheel.

Yours with thanks,

Jolyon

[Jolyon de FossardParticipant @jolyondefossard98326]

[Ian S CParticipant @iansc]

Jolyon, it may help others giving you information if you indicate what part of the world you live in. Ian S C

[KWILParticipant @kwil]

Max spindle speed quoted by (old) Myford is given as 870rpm in the ML7 Handbook.

[MadMikeParticipant @madmike]

Try clicking onto the Myford link on the right hand sioze of this page, that will take you direct to Myford. Why do you think a Colchester Student is too big? You can always do small work on a large lathe but the reverse is not the case. As Ian says above…..where are you located? There may be somebody local who can help.

[Jolyon de FossardParticipant @jolyondefossard98326]

Hi,

I'm in Bath, UK.

The Student's fine and I'm very happy with it; I just think that it's a bit over the top sometimes using a 3 HP machine to work on things 10mm dia and smaller. Very pleased with its ability to turn some steel into a pile of swarf and I can work to a thou on it so it's still accurate enough.

I just wanted something smaller and this ML7 was given to me so I'm determined to get it running but was surprised that it can't spin as fast as the Student.

I make parts for turntables (record players) and sell them on-line. I'm an electrician by trade but it's not as much fun as a day in the workshop with my machine tools, a teapot and the radio.

Yours,

Jolly

[pierre ehly 2Participant @pierreehly2]

Hi joylon,

The ML7 manual say

640 Rpm ( 1"7/8 pulley & 1450 Rpm motor)

870 Rpm (2"1/2 pulley & 1450 Rpm motor)

1070 Rpm (2"1/2 pulley & 1750 Rpm motor/ 60hz)

This higher value is the max safe Rpm, old babbit bearing manual say

100 meter/minute (330ft) linear speed is max , with heat contol (hand touch)

The probleme is less modern lubricant than heat evacuation.

Certainly too much modication for the benefit

brgds

pierre

[_Paul_Participant @_paul_]

I have a 1949 ML7 with white metal bearings I do on occasion run it over 1000 rpm using ISO32 oil in the oilers, never seems to be an issue with bearing heat or siezure.

When I last changed the spindle drive belt there was no appreciable maks on the bearing surfaces.

regards

Paul

[Jolyon de FossardParticipant @jolyondefossard98326]

Thank you both.

I'll make a motor pulley that'll get me to 1070 rpm and use Castrol Hyspin 32 maybe with some Molyslip in and I'll take care !

Yours,

 

Jolly

Edited By Jolyon de Fossard on 15/10/2012 16:13:27

[David Clark 13Participant @davidclark13]

Hi There

I fitted a 2,800 RPM motor to an ML7 and ran it for a long while before I sold it.

Never had a bearing problem.

regards David

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi JDF ,

Myford sold an upgrade kit for ML7 consisting of new hardened spindle and bronze bearings . Properly fitted and adjusted the new spindle and bearings were good for 2000 rpm running for extended periods and probably ok for much higher speeds .

It is sometimes the case that out of balance problems limit the speed that can actually be used .

Just a mention of something that can occur if running ML7 faster than original design speed :

Heat build up causes spindle to expand longwise and jam up the thrust bearings . No problem if you know in advance – just ease them off a bit .

Regards ,

Michael Williams

[David Clark 13Participant @davidclark13]

Hi There

They used the bronze bearings and hardened spindle in the C7 capstan.

However, knowing they were available as extras means that you could probably replace the whitemetal bearings with home-made bronze ones as long as you do not run at to high a speed..

regards David

[Jolyon de FossardParticipant @jolyondefossard98326]

I could make some Bronze (NAB I assume) bushes on my Colchester and maybe get the spindle Nitrided or would Nitriding require grinding afterwards ?

Yrs,

Jolly

[David Clark 13Participant @davidclark13]

Hi There

Nitriding would not require grinding afterwards. It is a very thin depth of hardening.

Not sure if you need special nickel chrome steel though.

I know Seagull outboard crankshafts were.

We just used to polish them where the grinding had missed it in the corners.

regards David

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Q: Not sure if you need special nickel chrome steel though.

You do and it has to have an Aluminium content as well .

Really and truly with a spindle that is already probably undersized and made of unknown steel I would personally stay away from hardening .

Unless you want to make or buy an all new hardened spindle I suggest that you polish up the journals on the existing one and run spindle in DIY Glacier bronze bearings . Would be worth  making the bearings a couple of atoms undersize and scraping them in and also worth scraping proper oilways .

If your regular use of the lathe is just making the 10 mm bits and pieces that you mention then the bearing loads are almost nothing and Glacier bronze bearings running on old shaft will last forever given plenty of oil .

Michael Williams .

Edited By MICHAEL WILLIAMS on 15/10/2012 18:42:35

[Andrew Moyes 1Participant @andrewmoyes1]

I ran my ML7 for several years with a 2800 rpm motor and variable speed drive until I upgraded to a Super 7 Plus. The top speed was 1350 rpm and there was absolutely no problem with the bearings, which had 1/2 thou clearance and only got slightly warm after prolonged running at high speed. Myford sold a two speed 2800/1450 rpm motor for the ML7 in the 1970s for use with the ML7 so they can't have thought there was a problem. It was a good modification and made drilling with small drills much easier.

The reason given for the change to the hardened shaft and bronze bearings was the prohibitive cost of white metal bearings, not that they were inferior.

Andrew M

[Jolyon de FossardParticipant @jolyondefossard98326]

Hi Chaps,

Thank you all for your very helpful comments. It looks like I shouldn't worry about this but wanted to hear the experience of others before I went ahead.

Currently, the lathe has small metal oilers. I'll replace these with the tall glass ones so I can see the oil level and and adjust the flow.

Kind regards,

Jolyon

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Just for general interest :

Bearing materials need to be chosen on basis of running speed , bearing load , effectiveness of lubrication and life needed between renewals .

For a lathe with a moderate usage factor and moderate loads and speeds an unhardened shaft working in whitemetal bearings is certainly quite adequate . As the load , speed and usage go up better bearings come to be needed .

Myford realised this very early on and as DC points out the the C7 series had hardened shafts and bronze bearings almost from the start . The later S7 series also had hardened shafts and bronze bearings at the more highly loaded nose end as did some of the Myford high speed grinders .

Anyone with a bit of spare time can work out the actual and allowable bearing loads and Z numbers for each of the Myford bearing configurations and estimate which is the best for long term endurance .

Michael Williams .

[julian atkinsParticipant @julianatkins58923]

the Myford Super 7 was primarily designed to give a much higher top speed than the old ML7.

if you run your old ML7 at much higher than the stated top speed (which will require some steppng up on the drive anyway or a faster motor) then please be very careful!

what a lovely gift!

leadscrew handwheels are easy to obtain… i saw quite a few on sale at very reasonable prices at last year's midlands exhibition. you will definitely need the oilers for your top speeds! they arent difficult to make but can easily be bought too. i would stick to the myford oil specification carefully, and before you run your ML7 at top speed make sure the bearings have been cleaned etc, and not too tight and keep a regular check on the temperature with the palm of your hand as loco drivers do on loco bearings! if you are drilling with very small drills eg for injectors then an added sliding drilling spindle to the tailstock can be recommended to increase the speed.

cheers,

julian

[Jolyon de FossardParticipant @jolyondefossard98326]

HI,

I have to say that I am thrilled with the lathe. Now it's been taken apart I can see that it is in lovely condition mechanically. I learned to turn on my Dad's ML10 (he's a clockmaker by profession) so having a Myford in my workshop is quite something. Also, compared with Colchester, spares seem cheap !

Apart from the aforementioned bits and pieces I'll I'll need is an MT2 dill chuck, live centre and a Dickson tooolpost then I'll be a way. Oh yes, and I'll have to make a bench for it.

As an aside, where can I buy QWhite Metal for making bearings ?

Yrs,

Jolly.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Jolyon de Fossard on 16/10/2012 08:22:17:

As an aside, where can I buy QWhite Metal for making bearings ?

Yrs,

Jolly.

Alec Tiranti is a good supplier.

MichaelG.

[Brian Holmes 1Participant @brianholmes1]

Hello Jolly

There is a dealer in Neston,Near Corsham, Wilts which is about 10 miles from Bath. He specialises in Myford lathes.

Brian

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

You need engineering grades of whitemetal for bearings . Read through these earlier postings :

**LINK**

Regards ,

Michael Williams .

[Michael GilliganParticipant @michaelgilligan61133]

Posted by MICHAEL WILLIAMS on 16/10/2012 08:50:42:

You need engineering grades of whitemetal for bearings . Read through these earlier postings :

**LINK**

Regards ,

Michael Williams .

A Lead-free "Bearing Grade" is available from Tiranti

… and other stockists, I'm sure.

MichaelG.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Now tell me what it is and why it is suitable . In fact why not tell us all how to design a plain bearing and choose appropriate materials from the bottom up . Don't omit all the lubrication considerations .

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