Unimat3 vs. Sherline lathes

[Michael GilliganParticipant @michaelgilligan61133]

I was struggling a little with the semantics there ^^^
Axial play [albeit very small] surely does NOT constitute preload !

So, I went back to the Sherline Horse’s mouth … and yes, that’s the the claim:

https://www.sherline.com/product/sherline-standard-morse-1-taper-spindle-headstocks/#description

“Separated by a common language” might be an appropriate expression.

MichaelG.

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Edit: __ video demonstration

https://youtu.be/G0mUTf2q4bY?feature=shared

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[Michael GilliganParticipant @michaelgilligan61133]

This chap seems to have a fuller vocabulary:

https://youtu.be/lSiTwOUh-mU?feature=shared

MichaelG.

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https://youtu.be/lSiTwOUh-mU?feature=shared

[JasonBModerator @jasonb]

I like the way the Sherline guys says you can’t really do it yourself then goes on to showing you how to alter the setting😂

[david bennett 8Participant @davidbennett8]

Michael, it falls into place when you consider preload to be positive or negative. With deep groove bearings, as here, it is negative.

dave8

[Kiwi BlokeParticipant @kiwibloke62605]

I suspect I’m not the only one to watch the Sherline video in MG’s link with eyebrows raised and jaw slack.

So, for Sherline, axial play = preload? Nonsense! If stiffness of a bearing-supported precision spindle is the aim – and surely it is – Sherline have a funny way of going about it: bass-ackwards! It doesn’t even make sense if they fit their bearings with the inner races expanded enough to eliminate radial play – and they won’t! And then they advocate ‘looser’ C5 bearings…

[JasonBModerator @jasonb]

Might depend where you set your “zero” if you take it as the neutral position where the Sherline guy in the video started then he has added positive preload.

[SillyOldDufferModerator @sillyoldduffer]

[Kiwi BlokeParticipant @kiwibloke62605]

[david bennett 8Participant @davidbennett8]

Don’t forget, in this discussion we are concerned with deep groove ball bearings. They have different requirements from e.g.angular contact bearings. In Michaels second video, the chap seems to prefer referencing “total internal clearance” His video is talking mainly about angular contact bearings, but briefly mentions deep groove types at about 4.40.

dave8

[Graham MeekParticipant @grahammeek88282]

When the USA were considering purchasing the Harrier way back. In mock battles arranged with the RAF and USAF in the USA. The RAF actually downed more F?? (what ever it was) than the Harrier. Apparently the trick was to go into the hover and let the faster guy go by. Sort of Air Brakes.

Clearly the RAF knew a thing or two about using their equipment to their best advantage.

Back to the main plot.

SKF list their 6003 ZZ bearing (What is used in the Unimat), as being able to withstand 730 lb of Static Load. The Axial loading is rated at 365 lb. (Please note I have done the conversion to lb, as that is what I measured the Pre-load in, SKF use Newtons). Thus the actual Preload of 28 lb that I measured is 7.5% of the maximum allowable. This will hardly stress the bearing or cause friction. They are after all anti-friction bearings.

The easiest way out of this is for the OP to purchase a Sherline. Rather than mutilate the poor Sow’s Ear.

Regards

Gray,

 

[JasonBModerator @jasonb]

[david bennett 8Participant @davidbennett8]

[JasonBModerator @jasonb]

Question is would 13lbs take all the endfloat out of a Sherline spindle, You are assuming there is no actual load being applied to reduce the natural play in the bearing down to 0.0002″

Also consider the effect of heat. Usual to warm a lathe up to running temperature before adjusting the preload, no mention of this on the Sherline video. Quite possible that 0.0002″ cold play reduces as the head warms up. Do we know what teh Sherline hea dis made from?

[david bennett 8Participant @davidbennett8]

The play in the sherline spindle is down to 0.0002″ courtesy of the setting-up guy at sherlines factory.

dave8

[SillyOldDufferModerator @sillyoldduffer]

[Graham MeekParticipant @grahammeek88282]

[david bennett 8Participant @davidbennett8]

[JasonBModerator @jasonb]

[david bennett 8Participant @davidbennett8]

As I said earlier, we are not dealing with angular or taper bearings. They are deep groove bearings and sherline followed the correct procedure. Any expansion of the headstock would add play to the spindle not reduce it.

dave8

[duncan webster 1Participant @duncanwebster1]

Unless I’ve misunderstood the video (I couldn’t be bothered watching all 10 minutes) the inner faces of the bearing outer races abut shoulders in the aluminium headstock. Assuming the spindle and headstock warm up equally, increased temperature reduces axial play, which is why you need to set it higher for higher speed (and therefore temperature)

 

[david bennett 8Participant @davidbennett8]

Come on now! Aluminium expands much more than steel. Therefore the aluminium shoulders move apart faster than the steel expands.

dave8

[duncan webster 1Participant @duncanwebster1]

Yes but the shoulders are pushing the outer races apart, and the steel is stopping the inner races moving apart, so the clearance is reduced.

[JasonBModerator @jasonb]

Yes that is my thinking Duncan. As the aluminium head expands more than the spindle the outer races will be moved further apart than the inner races that are retained by slower expanding spindle and it’s nut so clearance will reduce.

This is the very reason why the gap needs to be more when used with the 10,000rpm pully as more heat is generated, head expands more so a bigger gap is needed to stop the bearings becoming excessively tight. Also the same reason it is always suggested to set bearing preload on a warmed up machine.

Sherline have a way of doing it on a cold one that gives the desired running when warm.

[david bennett 8Participant @davidbennett8]

[JasonBModerator @jasonb]

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