you can use angular contact bearings which will be better on a lathe , I wouldn't bother on a mill . There are many that have used the origional bearings for years and have had no issues. Never seen belville or spring washers used ever and i would be removing them if they were fitted.

If the bearings in a lathe headstock are pre-loaded, either by adjuster nut on the spindle or by wavy washers, the clearance is taken up, so how would the extra clearance in a C2 be of any relevance?

The usual trick is to upgrade to angular contact bearings or even better taper rollers. ISTR the ArcEurotrade website has an article on doing the conversion.

Edited By Hopper on 30/12/2018 12:17:31

The design of that headstock is terrible , the axial load from the cutting tool is baring against a circlip not a machined shoulder in the headstock .

The wavy washer only controlls the end float of the spindle in one direction which is fine if you never want to machine anything feeding the carriage away from the chuck.

I am glad i never bought a unimat if their headstock set up is the same through all the small models they make !

Cool, furnish us with your engineering reasoning for that!

I think it's true to say that a Belville washer is an elegant economy driven feature that in practice, I've never found to be an issue on my Compact 5. If I was turning propshafts for an aircraft carrier then I'd want a substantially rigid machine but for light model engineering work, I've never yet taken a heavy cut away from the headstock that has overcome the force exerted by the washer. Even if it made itself known, one can always turn the item around in most cases and alter the cutting direction towards the chuck. Most tools require a little adaption of work practices to their idiosyncrasies. I've owned mine for maybe eight or nine years and it's never been an issue.

I suspect the same, and there's always a possibility the gain isn't worth the pain. The problem with up-rating any machine is that some other factor comes into play and you have to fix that as well to get any benefit. Perhaps many upgrades will be needed.

I'd welcome a before and after comparison showing the effect of changes on actual work. If you can't show the modification made a difference, it wasn't worth doing!

However, I have a utilitarian view of tools – I am a barbarian. No way would I ever bother to replicate an old lathe's original colour scheme! But that's just me – if improving a lathe makes the owner happy that's a jolly good reason for doing it.

Dave

P.S. Looking at the geometry, with ever reducing clearances the static radial load increases significantly under any preload, which is not what you want for good bearing life.

Neil

Imagine two extremes, a close fitting bearing and a loose bearing. In both cases there will be a 'wedging' effect, just as with a taper roller bearing, but less extreme.

Put axial preload on a loose bearing and the balls will bear on the sides of the race, where it is at an appreciable angle.

Take the close fitting bearing, now the bearings cannot move away significantly from the centreline of the races. The contact angle is now much less, greatly increasing the radial load.

Axial load:axial load varies with the inverse of the tangent of the contact angle.

With angular contact bearings the angle is designed to be about 45 degrees so axial and radial forces are roughly equal.

For taper rollers about 20 degrees might be typical, but the long contact surface compensates for the high radial loading.

I found this: http://www.astbearings.com/ball-bearings-radial-play.html

"When a ball bearing is subjected to thrust loading, a higher contact angle will result in reduced ball to raceway stresses. Greater values of radial play result in higher values of contact angle. Under these conditions, this will provide longer bearing life, lower torque, and less axial deflection. In a pure thrust situation, a 15° increase in contact angle can result in over a 70% reduction in contact stress (ball-to-raceway)."

Neil

Neil beat me to it.