401 bearing issues

301, 401, plinths and assorted idler stuff
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shane
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#46 Re: 401 bearing issues

Post by shane »

When we designed the TT2 we did find that there were slight audible differences between oils used in the bearing. Forty years later I’m not going to try and describe the differences but they were noticeable, repeatable and definitely beyond the realms of expectation bias.
The TT2 bearing is a 10mm diameter ground steel shaft running in a polished hole bored down a piece of brass hex bar. The bottom of the bore is plugged and a 10mm ball bearing sits on the plug. The bottom of the shaft is radiused with a flat ground on the end which sits on the ball. The length of the shaft in the bearing is around 70mm.
This means that there’s a high point loading where the shaft sits on the ball, and a large lightly loaded sliding surface between the side of the shaft and the bearing bore.
Being concerned about the wear between the ball and the bottom of the shaft, we tried various oils including EP90 gear oil, ornery 20-50, light machine oil and a weird concoction containing microscopic PTFE ball that we had lying around for some reason.
In simple terms, the result was the thicker the oil, the worse the sound, and we ended up using a light machine oil from Shell. We bought a 5-litre can, and when I left Heybrook it was still two thirds full after about 2000 turntables. The fears about wear on the bottom of the shaft were unfounded. Mine now show a barely visible witness mark.
The only reason I can think of to explain the difference in sound is the increased drag of the thicker oils loading up the motor and belt, but it was a very real effect.
From what I remember, the 401 bearing has two bushes at the top and bottom of the bearing sleeve, so the sliding surface area would be much less and the effect may well be less noticeable.
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Paul Barker
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#47 Re: 401 bearing issues

Post by Paul Barker »

Thanks Shane
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pre65
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#48 Re: 401 bearing issues

Post by pre65 »

I rebuilt my 401 shortly after I got it, many years ago, and I honestly can't remember what oil I used for the bearing.

Should I need to re-oil it I'd probably use ATF, as A) I have a 5ltr can left over from my old Volvo transmission flush and B) It looks thin enough.

But, as Share has said, perhaps thicker gear oils are best avoided.
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#49 Re: 401 bearing issues

Post by IslandPink »

It probably depends on the details of the bearing and what work has been done on it.
Remember the 301's used grease rather than oil.
However some of this is probably because of the loose tolerances and the need to damp things.

I remember the story about the Teres turntable and how they increased the size and area of the bearing to get more drag. If the motor is quiet enough when working against the bearing drag, then the theory was that the record-induced speed-variations would be lower, if the motor was already working against a frictional load.
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#50 Re: 401 bearing issues

Post by izzy wizzy »

IslandPink wrote: Sat Jun 10, 2023 6:00 pm It probably depends on the details of the bearing and what work has been done on it.
Remember the 301's used grease rather than oil.
However some of this is probably because of the loose tolerances and the need to damp things.

I remember the story about the Teres turntable and how they increased the size and area of the bearing to get more drag. If the motor is quiet enough when working against the bearing drag, then the theory was that the record-induced speed-variations would be lower, if the motor was already working against a frictional load.
Yup to all of that. That was the theory to start with for the Teres yet as the drive developed/changed, many ended up at air tool oil. Possibly with the direction moving to a "stiff" belt. Galibier, an off shoot of the Teres project, same. I seem to remember auto transmission oil was selected at one point.

The whole drive system's dynamics is wrapped up in this loop of motor, drive, inertia and drag which is not constant due to the load varying. It's a complex relationship so oil does make a difference if you can be arsed to play with that parameter.
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#51 Re: 401 bearing issues

Post by pre65 »

izzy wizzy wrote: Sat Jun 10, 2023 9:16 pm
I seem to remember auto transmission oil was selected at one point.
If anyone in the UK (forum members only -even Dennis) want's to try ATF (Automatic transmission fluid) then send me a non glass container and I'll send you a sample for the cost of return postage.

My ATF is special for Aisin Warner automatic gearboxes but I don't know what's different to other ATFs.
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#52 Re: 401 bearing issues

Post by shane »

As a footnote to my post above, I seem to remember something about the additives in EP gear oils being corrosive for brass, but the details elude me.
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
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#53 Re: 401 bearing issues

Post by Paul Barker »

Thanks again Shane, I recall that also, but I dont think it applies to hydraulic oil. Seems from youre statement thick oils like EP didn’t sound as good anyway.

Mark early “Grease Bearing” 301’s were worth more when Darren was buying turntables for Slatedeck.

However my 301 is not a grease bearing. We also discovered by accident there were at least two different profiles of 301. Mine is the smaller (earlier) of the two we know of (there may be others) you make a plinth for the one you have not for a specific pattern; send a standard pattern it to the guy with the smaller plinth, and you get air gaps which you see daylight through. Just looks shoddy but works OK.

I just like the sound of mine. Darren gave me a small yellow squease bottle of oil to use in mine, but he didnt tell me what oil it was. Sounded good to me. Unfortunately Roxy chewed it and it’s bone dry.

Phil I’ll get a new squeese bottle to send you please?

Anth I really must come and get my turntable. Now its summer and I am contracting, some days I have no work. So would it be OK if I contact you short notice to see if you’ll be there. I only find out in the same day whether I have work day. They give priority to their salaried engineers.
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#54 Re: 401 bearing issues

Post by pre65 »

Paul Barker wrote: Sun Jun 11, 2023 7:41 am T
Phil I’ll get a new squeese bottle to send you please?

Paul, I can probably find one bottle, so just PM me with your address.
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Paul Barker
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#55 Re: 401 bearing issues

Post by Paul Barker »

Thanks
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#56 Re: 401 bearing issues

Post by rowuk »

If you are going to use thin oil, make sure that the bearing is sealed on the bottom. There is nothing worse than oil dripping on something electrical...
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#57 Re: 401 bearing issues

Post by Ant »

Yep just give me a shout as and when paul im pretty much always in
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#58 Re: 401 bearing issues

Post by vinylnvalves »

When I played about with Garrards back in the mid nineties, a visit to Tom Fletcher, was enlightening. He used sewing machine oil for his Nottingham Analogue turntables, he told me that I needed something more viscous for the Garrards, as they needed some resistance, to control speed. If I remember correctly he gave me a jam jar of some oil from his Colchester lathe. I ended up making a couple of record cleaning machines out of them, as I couldn’t get them to sound right.
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#59 Re: 401 bearing issues

Post by IslandPink »

vinylnvalves wrote: Mon Jun 12, 2023 6:29 am When I played about with Garrards back in the mid nineties, a visit to Tom Fletcher, was enlightening. He used sewing machine oil for his Nottingham Analogue turntables...
Thanks for the insider tip !
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#60 Re: 401 bearing issues

Post by Paul Barker »

Collected my 301 from Anth yesterday. We think my 301 is a grease bearing…..

Steve I dont get youre take on Garrard at all.

Now Ive no idea if anything Shane said has any relevance to the grease bearing Garrard either. Even though his contribution was very interesting.

Phil thank you for posting the ATF. I’m not sure any more if its of use. Need to find someone with knowledge without bias about Garrards, to get a starting point.
"Two things are infinite, the universe and human stupidity, and I am not yet completely sure about the universe." – Albert Einstein
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