STD 305M main bearing question

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Trio KD1033
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STD 305M main bearing question

Post by Trio KD1033 » 25 Dec 2015 02:40

Merry Christmas all! (if you celebrate it)

First post here, not sure if I'm supposed to post in an introductory section first, but here goes anyway.
I recently added a rather nice STD305m to my collection of decks, and would like to know something about the main bearing. Does anyone know if it is a point contact like a thorens TD160, or does it have a ball bearing, more like a Rega Planar?
Truth is, it's not the quietest of bearings. I can hear a gentle swishing sound from it in a completely silent room. I've cleaned it out and replaced the oil with some 0-30w synthetic, but the gentle noise persists. Looking down in to the housing I couldn't tell if there was a ball there or not. The odd thing is, even with this apparent mild noise, it is actually very quiet with regards to playing a record. Compared to my Technics SL-1500 mk1, for instance, it is slightly quieter, despite the Technics appearing to be mechanicaly smooth as silk. The reason I ask about the ball is that some sources seem to think there is one, while others don't, and I worry that I'm running without. Mind you, I would imagine it would either grind to a halt and/or ride too low if that was the case!

Any comments from STD 305 users?

Apologies if this is all nonsense, it's 2:40am here in the U.K. and I'm fairly drunk.

Andy

Alec124c41
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Re: STD 305M main bearing question

Post by Alec124c41 » 25 Dec 2015 03:26

When you cleaned out the bearing, was the bottom of the spindle flat, or dit it have a rounded point?
If it is flat, there should probably be a ball at the bottom. These can develop flat spots, but are easily replaceable.

Cheers,
Alec

Trio KD1033
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Re: STD 305M main bearing question

Post by Trio KD1033 » 25 Dec 2015 08:17

Alec124c41 wrote:When you cleaned out the bearing, was the bottom of the spindle flat, or dit it have a rounded point?
If it is flat, there should probably be a ball at the bottom. These can develop flat spots, but are easily replaceable.

Cheers,
Alec
Hi Alec, thanks for answering.

The base of the spindle was, I would say, gently rounded (convex) but far less so than for instance a thorens td160 bearing that looks somewhat more pointed. You'd think it would be obvious wouldn't you? Perhaps I should get a photo of it. There is a fairly obvious flat worn on it, but I wondered if that was a result of running without a ball bearing, as well as age. It is about 38 years old. Like you, I would imagine a ball type spindle to be pretty flat. It is extremely difficult to see well into the housing. My eyesight, even with glasses is not what it used to be, and as soon as you get close, you block your own light!

I'll get a photo of the spindle up later.

Cheers!
Andy

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Re: STD 305M main bearing question

Post by Copperhead » 25 Dec 2015 13:45

Trio KD1033 wrote:The base of the spindle was, I would say, gently rounded (convex) but far less so than for instance a thorens td160 bearing that looks somewhat more pointed. You'd think it would be obvious wouldn't you? Perhaps I should get a photo of it. There is a fairly obvious flat worn on it, but I wondered if that was a result of running without a ball bearing, as well as age.
It needn't be as "pointed" as the Thorens, as longs as it is convex contact with its mating surface will be minimal. A ball bearing would just circle a convex shape, keeping it central would be impossible.

Sounds like your bearing might have been run without lubrication, this would explain the flat spot you see. You could get the bottom of the spindle re-machined, then add a thrust pad of suitable thickness to make up for the material removed.

You can shine a torch down the well, maybe you will find a worn thrust pad there.

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Re: STD 305M main bearing question

Post by Trio KD1033 » 25 Dec 2015 14:24

Copperhead wrote:
Trio KD1033 wrote:The base of the spindle was, I would say, gently rounded (convex) but far less so than for instance a thorens td160 bearing that looks somewhat more pointed. You'd think it would be obvious wouldn't you? Perhaps I should get a photo of it. There is a fairly obvious flat worn on it, but I wondered if that was a result of running without a ball bearing, as well as age.
It needn't be as "pointed" as the Thorens, as longs as it is convex contact with its mating surface will be minimal. A ball bearing would just circle a convex shape, keeping it central would be impossible.

Sounds like your bearing might have been run without lubrication, this would explain the flat spot you see. You could get the bottom of the spindle re-machined, then add a thrust pad of suitable thickness to make up for the material removed.

You can shine a torch down the well, maybe you will find a worn thrust pad there.
Thanks Copperhead.

Hear is a photo of the bearing, it looks like it has been run in sandpaper!
Flash photos with good macro lenses aren't flattering though!
Some apparent damage on the left hand side of the spindle is a bit of oil running down.
I should probably wipe it clean before shooting.
https://farm2.staticflickr.com/1625/233 ... 0ca7_z.jpgSTD 305M Turntable Main Bearing by Andy Likes Cameras, on Flickr

https://farm2.staticflickr.com/1469/238 ... 5914_z.jpgSTD 305M Turntable Main Bearing by Andy Likes Cameras, on Flickr

I tried shining a torch down the housing but it's pretty deep. When you line your eye up with the bottom of the housing it's really tough to get the light in there as well.
There does appear to be a flat, and a very small dimple worn on it doesn't there?

Andy

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Re: STD 305M main bearing question

Post by Copperhead » 25 Dec 2015 14:50

Yes, it looks like there is a dimple caused by a ball bearing on the bottom of that spindle. Could be that the flat is machined and it does use a ball bearing. Seems strange that it would wear so much and have a dimple! Also, the concentric rings on the base look like machining marks, rather than wear. If it is wear, it is rather severe!

The answer will soon come, I am sure. Most Brits are now too stuffed to think straight, give it a few hours and you are bound to get a definitive reply.

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Re: STD 305M main bearing question

Post by Trio KD1033 » 25 Dec 2015 15:08

You're right Copperhead! Me amongst them!

Mmm. I've managed to see where the thrust pad or ball bearing would be at the bottom of the housing. There appears to be a dimple of wear there very similar to the dimple on the end of the spindle. This suggests to me that a ball may be missing. The previous owner seemed to think there was a ball, but wasn't sure. If that's true, I'm surprised it runs as well as it does!

Cheers!

Andy

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Re: STD 305M main bearing question

Post by Copperhead » 25 Dec 2015 15:44

Trio KD1033 wrote:You're right Copperhead! Me amongst them!

Mmm. I've managed to see where the thrust pad or ball bearing would be at the bottom of the housing. There appears to be a dimple of wear there very similar to the dimple on the end of the spindle. This suggests to me that a ball may be missing. The previous owner seemed to think there was a ball, but wasn't sure. If that's true, I'm surprised it runs as well as it does!

Cheers!

Andy
Hello Andy, sorry mate, thought you were on the other side of the pond. Only just spotted the st John's under your name!

Get yourself a ball bearing and you should be alright, don't keep running the deck without it as it will just cause more wear. All you need now is to know the right size for the ball, not too hard a mission as re-machining that spindle would be.

The scratches on your spindle should not affect its running, you will need to really clean everything thoroughly. There could be metallic debris stuck in the well that when mixed with oil might end up scoring the rest of the spindle.

Vinnie.

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Re: STD 305M main bearing question

Post by Trio KD1033 » 25 Dec 2015 16:10

No problem Vinnie!
Upon further investigation with a cotton bud, I can feel that there is a captive ball bearing!
I say captive because when I cleaned out the bearing I removed the whole housing, turned it upside down and shook it hard. Even tapped it on a soft surface but no go. I was hoping to rotate it to a fresh surface. Most of the swishing sound I get seems to come from the upper support bushing. I believe they were known for this, but for all my searches on STD decks, nobody seems to mention the bearing apart from one fella who was a Hi-Fi dealer in the 70s and 80s. He said that the 305 often displayed wear on the upper spindle.

Now back to the mince pies and beer/port!

Andy

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Re: STD 305M main bearing question

Post by Copperhead » 25 Dec 2015 16:28

Trio KD1033 wrote:No problem Vinnie!
Upon further investigation with a cotton bud, I can feel that there is a captive ball bearing!
I say captive because when I cleaned out the bearing I removed the whole housing, turned it upside down and shook it hard. Even tapped it on a soft surface but no go. I was hoping to rotate it to a fresh surface. Most of the swishing sound I get seems to come from the upper support bushing. I believe they were known for this, but for all my searches on STD decks, nobody seems to mention the bearing apart from one fella who was a Hi-Fi dealer in the 70s and 80s. He said that the 305 often displayed wear on the upper spindle.

Now back to the mince pies and beer/port!

Andy
Strange, I would have thought, from looking at the scoring, that the ball would be missing and the spindle running directly on the thrust pad's surface. There should not be any marks on the bottom of that spindle at all, the ball bearing would ensure that the domed part does not contact anything but it. Could be that the ball bearing has sank in the thrust pad, or the bearing was run without the ball for some time. Either way, you need to work out what is happening and perhaps run a thicker oil.

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Re: STD 305M main bearing question

Post by Trio KD1033 » 25 Dec 2015 16:37

Copperhead wrote:
Trio KD1033 wrote:No problem Vinnie!
Upon further investigation with a cotton bud, I can feel that there is a captive ball bearing!
I say captive because when I cleaned out the bearing I removed the whole housing, turned it upside down and shook it hard. Even tapped it on a soft surface but no go. I was hoping to rotate it to a fresh surface. Most of the swishing sound I get seems to come from the upper support bushing. I believe they were known for this, but for all my searches on STD decks, nobody seems to mention the bearing apart from one fella who was a Hi-Fi dealer in the 70s and 80s. He said that the 305 often displayed wear on the upper spindle.

Now back to the mince pies and beer/port!

Andy
Strange, I would have thought, from looking at the scoring, that the ball would be missing and the spindle running directly on the thrust pad's surface. There should not be any marks on the bottom of that spindle at all, the ball bearing would ensure that the domed part does not contact anything but it. Could be that the ball bearing has sank in the thrust pad, or the bearing was run without the ball for some time. Either way, you need to work out what is happening and perhaps run a thicker oil.
Agreed, the wear does look like it's been run without a ball. I could just about feel the rise and fall of what I think is the ball at the bottom. I'd love to see a cut away diagram of the assembly, that would help What really amazed me was how quiet it is with regards to rumble. The whole assembly is so heavily damped. Didn't want to accelerate the wear any more though. What sort of oil grade would you try?

Andy

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Re: STD 305M main bearing question

Post by Copperhead » 25 Dec 2015 16:58

Shine a torch down the well, you should be able to inspect it properly then.
If indeed there is a ball, add some alcohol and hopefully the ball will come out. Might be stuck due to sticky old oil holding it in.

I am by no means an expert on lubricants, and some bearing bushes are made different than others, but I use Redline 5W 30 for bearings with a bit of slop and thin oil for tight tolerances.

Get yourself a small torch, a £ shop one will do, you really need to see what is happening down below.

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Re: STD 305M main bearing question

Post by Trio KD1033 » 25 Dec 2015 18:00

Copperhead wrote:Shine a torch down the well, you should be able to inspect it properly then.
If indeed there is a ball, add some alcohol and hopefully the ball will come out. Might be stuck due to sticky old oil holding it in.

I am by no means an expert on lubricants, and some bearing bushes are made different than others, but I use Redline 5W 30 for bearings with a bit of slop and thin oil for tight tolerances.

Get yourself a small torch, a £ shop one will do, you really need to see what is happening down below.
Will do, cheers Vinnie.
Andy

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Re: STD 305M main bearing question

Post by Alec124c41 » 25 Dec 2015 23:26

You might try adding a dab of moly-lube.

Cheers,
Alec

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Re: STD 305M main bearing question

Post by Trio KD1033 » 25 Dec 2015 23:40

Alec124c41 wrote:You might try adding a dab of moly-lube.

Cheers,
Alec
Hi Alec,

I've just entered Moly-Lube into Amazon.co.uk, and it comes up with a few different products.
Is there a specific one to use? I'm guessing it's a bit thicker than the usual stuff used for turntables.

Andy.

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