Clarify some plain bearing engineering principles please.

[samuel heywoodParticipant @samuelheywood23031]

In context , I’m wanting to rebuid my vinyl turntable. Upgrade parts are available, but given the cost, i’d rather build myself, & hopefully learn something in the process.

Your typical turntable spindle is a highly polished s/s shaft sitting in a close tolerance plain sleeve (in my case of brass)

Any reason to polish? we’re talking 33 1/3 rpm not a 20,000rpm model ic engine.

Thought to use silver steel for this, either hardened or unhardened & thought the ground finish might aid in oil film retention? Any thoughts?

Also on a web search, it was stated for the platter, more edge weight is good (flywheel effect, fairly obvious that one) & LOWERS the bearing noise. Is that correct?? doesn’t seem logical, though i’m not a trained engineer (not realy an untrained engineer either! lol)

Also it was stated inboard weight on the platter assembly would add to bearing noise, which is a big no no in audiophile terms.

But to me this sounds counter intuitive.I’ve always understood the closer to the bearing any rotating mass is the less  load on the actual bearing.

So, was the web post someone just talking off the top of their head  or is there something i;m not aware of? or are turntables  a special case?

In actual point of fact i should like to add some inboard rotating mass to my redesign & would like to hear from some engineers, professional or amatuer before  i start making any chips.

 

Thanks

[John HaineParticipant @johnhaine32865]

Provided the added mass is balanced around the bearing there is no way the bearing knows where it is.  But adding it near the rim increases the moment of inertia more which helps speed constancy.

Why change the bearing?  Unless it’s worn it should be fine.  Usually they rest on a single bearing ball at the bottom of the sleeve to take the weight.  The ball may have worn at the point where the shaft rests on it, in which case you could rotate it to expose a different point.

[samuel heywoodParticipant @samuelheywood23031]

Thanks for the reply John.

Yes the shaft rests on a ball bearing, with a loupe i found this quite pitted, so  i have replaced,cheap enough.

There’s nothing wrong with the bearing sleeve or spindle, 30+ years old & it takes a couple of minutes to re-seat as the air is expelled.

 

It’s what the spindle is attatched to i want to re-engineer, if i can’t make something better even with my limited skills, there’s something wrong. Hence neededing to make a new spindle also.

[BazyleParticipant @bazyle]

Just some thoughts.
Where does bearing noise come from? Is it the shaft banging from side to side in the hole? Or bits of grit grinding between the surfaces (at a microscopic level)? Or variations in friction slowing the rotation in a random way?

If the table is perfectly balanced there is no load on the main bearing apart from handling the gyroscopic effect of the inconveniently rotating earth, regardless of whether the mass is near or far from the centre. Outboard mass by increasing the moment of inertia will dampen bearing noise if it is related to variations in speed due to little fluctuations in friction. I’m not sure of the other effects.

[samuel heywood]

On samuel heywood Said:

It’s what the spindle is attatched to i want to re-engineer…

 

Why, what’s wrong with it?

Julie

[bernard towersParticipant @bernardtowers37738]

Could it be noise from the motor???

[BazyleParticipant @bazyle]

Following on from recent clock related threads. 33 rpm is like a clock pendulum. I wonder if anyone has tried a Microset on a turntable, or perhaps there is a version of it for HiFI buffs.

[samuel heywoodParticipant @samuelheywood23031]

@ Bazyle,

With anything i’m interested in, i do a lot of reading, but no telling whether what you’re reading is correct, particularly on the web & in particular regarding the audiophile world.

If you thought model engineers were picky about the details… well they haven’t got nothing on the audiophiles!!!

From what i can gather a large part of the bearing noiseassociated with “poorer sound” is the metal on metal of the ball bearing/ spindle inerface.

Seen several “solutions”~ jewelled bearings, engineering plastic sandwiched between spindle & BB, Ceramic BB~ but a bit of research suggests ceramic on metal is not a good combination.

I’ll be adopting an experimential approach, value engineers’ input as the audiophile  world is a bit surreal to say the least.

Cables sound different if reversed for instance~ this is with an AC current!???

Well these days i doubt i’d hear any difference, but when i was young i can say, yes reversing the cable direction definitely influenced what i was hearing, even if i was never quite sure which way was actually “best.”

I’m taking an engineering approach on this one, make it the best i can manage, with a view on function AND form & call it a day.

The existing subplatter, which the drive belt runs o nhas runnout in both planes, 3-4 thou on the dia, quite sure i can manage 1 thou or less.

If i don’t manage that first attempt, i’ll re-do.

 

[Robert Atkinson 2Participant @robertatkinson2]

Unless you have a cylindrical or centerless grinder you will have trouble replicating the precision and finish of the existing shaft.
The “brass” bush is likely to be an oilite bearing. These are sintered and loaded with oil.

Robert.

[noel shelleyParticipant @noelshelley55608]

The old Garrard sp25 ? was a bit basic but a modern ish job you may find hard to improve on ? Bushes on the motor, belt drive and a spindle bush – what’s making the noise ? As john said the spindle sits on a single ball. Has the belt started to harden and have flats on it ? Good luck. Noel.

[samuel heywoodParticipant @samuelheywood23031]

@Julie ~see my previous post, excessive runnout on what it’s attatched to.

@Robert are you saying silver steel not up to the job? That’s precision ground, least i thought so? Maybe need to source UK made silver steel??

The brass “bush” is indeed brass,not oilite. A one piece sleeve.

Given some of the other less than excellent engineering on the turntable, i am quite impressed with the fit of the sleeve & spindle & that’s after 30+yrs use.

[samuel heywoodParticipant @samuelheywood23031]

@Robert ~ normally my “engineering” is “about right” I use digital verniers day to day, but i’m quite prepared to dig out the”special” “tenths” micrometers for this job,if needed.

[samuel heywoodParticipant @samuelheywood23031]

@Noel , no not Garrard, Rega.

Seems a whole cottage industry has sprung up on turntable “upgrades” but i’ll not purchase what i could make myself, cheaper.

I’ve rather made a rod for my own back, my electronics knowledge is limited, but i know just enough to get by .

Hot-rodded my ancient CD player,was astounded by the results for relatively little outlay (everyone knows by now that Vinyl sounds better than CD right?) & now i feel obliged to give the turntable similar attention.LOL.

[MacolmParticipant @macolm]

Agree with leave spindle well alone. For, eg silver steel, centreless grinding cuts a constant diameter, not necessarily circular (think of a 50p coin)! If the central ball thrust parts can be improved using good quality bits, that might help.

[samuel heywoodParticipant @samuelheywood23031]

@ Bernard ~ not sure i’ve got any excessive bearing noise, what i wanted was clarification as to the principles of bearing design, such that i don’t introduce any excess bearing noise.

@Bazyle~ thanks for that, lifes a learning curve , had to look up what a microset was.Sounds like it could well be useful in adjusting a turntable.

[VersabossParticipant @versaboss]

Ah well, nice to meet a hobby colleague!

It is quite a time now since I built a couple of bearings, and even sold a couple. But my bearings are strictly for Lencos (75/78), which have a very strong motor. The differences to the standard bearings are:
– a much stronger housing (steel)
– a thicker spindle (10 mm), running on a Delrin (or other synthetic bearing materials), rounded end without a ball
– only a short part of the spindle is thicker (14 mm) and made from Bronze, sometimes Aluminium Bronze, and running also in synthetic materials.

After more than 10 years, I possibly can’t remember all details, but these bearings worked perfectly and silent. Just today I enjoyed some Keith Jarret solo concerts, wonderful music!To comment what you wrote above: Brass is Not a suitable bearing material, ad the distribution of weight in the platter has imho no effect to the sound. Although I admit after 80 years I am possibly not qualified to comment.

How do they look:

 

Kind regards,
Hans

 

[Howard LewisParticipant @howardlewis46836]

Could the noise be Motor related/

If an AC motor, could be a 50 Hz coming through?

Or if a DC fed with pulsed DC to set the speed, maybe that could be a source of noise?

Or is there something else vibrating, even at low amplitude, so that you could be detecting a mechanical noise?

Howard

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Noel Shelly, Ah! the ole Garrard SP25’s, I must have turned the best part of a blinking good few kilos of vinyl on this pair, never heard much bearing noise in all the years I had them, and they were still in really good condition when I sold them to a budding young DJ. I even used them in Hunstanton once, for a Biker’s New Years Eve do.

Regards Nick.

[samuel heywood]

On 21 April 2025 at 20:28 samuel heywood Said:

…

In actual point of fact i should like to add some inboard rotating mass to my redesign & would like to hear from some engineers, professional or amatuer before  i start making any chips.

 

Thanks

If it’s a pressed or thin metal cast turntable, I’d leave the centre area alone completely. A lighter area there will allow some flexibility to absorb any minuscule vertical vibration from the bearing.

For a given total mass, the mass being at the centre or edge only changes the effect on the bearing itself if the mass is out of balance. The turntable should be perfectly balanced, so concentrating the mass towards the edge improves the inertial damping and reduces any possible flutter, with no effect on the bearing. Increasing mass should only ever increase the vertical load on the bearing.

Re-balancing after any modification is absolutely essential.

For the bearing itself, leave the sleeve part alone, just be sure its really clean and properly lubricated

The support ball could hypothetically be replaced by a large watch cap jewel – a fractionally domed ruby disc bearing, with a small block under it with a top recess to centre it and match the original ball height?

(Ruby bearings are used as they are lower friction than steel.)

Examples on ebay; a large one is typically around 2.5mm

https://www.ebay.co.uk/itm/192309962790

https://www.ebay.co.uk/itm/235981097987

 

[CirclipParticipant @circlip]

And the ‘Leak 2001’ had an acrylic acetal copolymer (possibly Delrin, can’t remember) bearing. ‘Rumble’ and ‘Wow and Flutter’ were heady terms bandied about in the heady days of the ‘New Gear’ of the sixties and seventies audio explosion. I remember a new audio term being generated by one of the audio ‘Experts’ who regularly had his test reports included in one of the Hi-Fi comics of the time.

At the next Hi-Fi exhibition (Harrogate, when absolutely essential vinyl played by 90% of exhibitors was JMJ’s Oxygene), our Chief Acoustic design engineer took great delight wandering round sporting a badge bearing “MUSICALITY” something I can hear – but you can’t. The red faced originator got the point.

Back to the ‘Rega’, I remember it coming out. Ultimate test for a noisy bearing, apply uncoupled drive to the platter, spin by hand, apply one end of a long bladed screwdriver (or dowel) to the bearing housing and Mk 1 Lughole to the other and listen. Works every time (Or used to). If it ain’t broke, don’t (Try to) fix it.

Regards   Ian.

Just to qualify, I was working in the design department of Rank Leak Wharfedale at the time.

[noel shelleyParticipant @noelshelley55608]

Hi Nick, I was not so much suggesting that the SP25 was bad as that there were VERY much better decks to be had. Having put a Decca cartridge in an SP25 which improved the sound quality, I robbed the piggy bank and bought a Pioneer deck. I could not afford a new cartridge so it was the Decca along with the same amp and speakers. By just changing the mechanical components The improvement in sound quality was staggering – at least to me. In pieces of music I knew well I heard bits in the background I’d never heard before !

Hey Samuel, There comes a point where any improvements will only be detected by lab equipment, the point at which this happens becomes less pertinent as we get older.

Ah, Ian The mention of the name Wharfedale, I bought a huge pair of EMI speaker as I had spotted a mistake in the pricing, The journey  to London in snow in an MGB to collect them nearly killed me ! Good Luck. Noel.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Noel Shelly, I wasn’t thinking that you were suggesting that they were bad, and they were very good for their time and price, and these two were the MK III, but I did swop out the cartidges for the V100 with diamond stylus.

Back then I bought a Decca record “How to, give yourself a stereo checkout” which among other tracks, had “Silent Grooves” on it, which showed up any rumble and hum, and these decks passed very satisfactory indeed.

My best deck I have is a Pioneer PL-3000.

Regards Nick.

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