STD 305M main bearing question

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Alec124c41
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Re: STD 305M main bearing question

Post by Alec124c41 » 28 Dec 2015 03:27

I asked about the underside of the housing, not the bottom of the well.
I don't think that there is anything missing. The spindle looks to have a flat bottom, and a ball onside would make a point of rotation.
The Lenco bearing housing, as well as some old Pioneer housings, can be opened from the bottom. the Lenco had a flat brass thrust plate, which often got a dimple from the point of the spindle. Reversing it was a quick fix.

Cheers,
Alec

Trio KD1033
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Re: STD 305M main bearing question

Post by Trio KD1033 » 28 Dec 2015 03:36

Alec124c41 wrote:I asked about the underside of the housing, not the bottom of the well.
I don't think that there is anything missing. The spindle looks to have a flat bottom, and a ball onside would make a point of rotation.
The Lenco bearing housing, as well as some old Pioneer housings, can be opened from the bottom. the Lenco had a flat brass thrust plate, which often got a dimple from the point of the spindle. Reversing it was a quick fix.

Cheers,
Alec
Hi Alec,

The underside is sealed in some kind of glue/sealant but through it you can see a circlip.

Andy

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Re: STD 305M main bearing question

Post by Alec124c41 » 28 Dec 2015 03:55

That stuff on the outside is to keep the oil from running out.
I do not think there is anything missing. The clip almost certainly is to keep the ball from falling out. If you use a magnet, I think you could move the ball, unless it is totally gummed in.
You could polish the smooth parts of the sides of the shaft. It looks as if it could use it. I use Peek. It is a paste of diamond dust, fine enough to polish a CD or DVD, and great for dustcovers. Clean it off when you are done.
You could remove the stuff on the bottom of the housing, and the clip, then the ball, but clips like to fly, and you would have to seal the whole thing up again. This might be more trouble than any gain would be worth.
I think that polishing the shaft, and using good lubricants, should be all you need.

Cheers,
Alec

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Re: STD 305M main bearing question

Post by Copperhead » 28 Dec 2015 04:18

Alec124c41 wrote:I asked about the underside of the housing, not the bottom of the well.
I don't think that there is anything missing. The spindle looks to have a flat bottom, and a ball onside would make a point of rotation.
Cheers,
Alec
Apologies, I misunderstood. As far as I can see, Andy is missing a ball. The photograph showing the ball is not that of Andy's bearing. Or is it? Either way, a bearing design likely to be noisy.
Lenco's ball is held captive by the spindle, so it only really rotates on the Delrin pad. The 305's spindle would not retain the ball, and probably neither would the dimple in the well. The ball bearing is either turning on one surface, or both, strange design.

Then again, I have seen new Lenco bearings running on two ball bearings. This will virtually guarantee the spindle never to be centred. Just goes to show perfection is not required in order to get sound out of a turntable.

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Re: STD 305M main bearing question

Post by Trio KD1033 » 28 Dec 2015 12:55

Here is the underside of the housing.
Very tempting to open it up and have a look isn't it?

https://farm6.staticflickr.com/5749/239 ... 8785_z.jpgbearing by Andy Likes Cameras, on Flickr

Andy

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Re: STD 305M main bearing question

Post by Alec124c41 » 28 Dec 2015 20:24

The Lenco looks like that, but has a plastic boot over it, instead of the sealant.
If that is epoxy, getting through it might be difficult, but I would say, go for it. Then you will know what is going on in there.
A plastic furniture foot, in the right size, will retain oil, later.

Cheers,
Alec

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Re: STD 305M main bearing question

Post by Trio KD1033 » 28 Dec 2015 21:26

That sealant is really hard! I might have a go at it though.
One thing I have discovered by looking inside the bearing through my camera, while moving it from side to side is that the centre of the raised area definitely has a circular recess. That means that the dimple worn into the spindle was made by something that is not there now.

Andy

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Re: STD 305M main bearing question

Post by Copperhead » 29 Dec 2015 00:15

Trio KD1033 wrote:That sealant is really hard! I might have a go at it though.
One thing I have discovered by looking inside the bearing through my camera, while moving it from side to side is that the centre of the raised area definitely has a circular recess. That means that the dimple worn into the spindle was made by something that is not there now.

Andy
As Alec pointed out, the sealant is probably epoxy, the stuff is a pain to remove and heat (around 200 degrees) is one of the only things which will break it down. You will have to drill out as much as you can and pick away at the rest. If you are intending to try heating it, make sure there is nothing likely to melt. Unlucky it wasn't the new Araldite Rapid, the stuff never hardens more than a bogey.

Are you sure it is domed? Garrard 301/401 bearings have a domed thrust pad, but then the spindle runs straight on that. The dome is a type of phosphor bronze and provides the sacrificial surface, which can be replaced.

The dimples in both surfaces of your bearing are there to locate the spindle. Without them, and in a bearing which exhibits play, the spindle would not be able to stay centred.

Personally, I would polish the bottom of that spindle and do away with the leaning tower of Pisa by using a Delrin thrustpad.

A ball which fits tightly in the well will ensure it doesn't move around, it will also sit on the dimple, whether the dimple on the bottom of that spindle would stop it from moving around is debatable. I reckon a smaller ball would have a better chance as it would sit in the dimples more firmly. Why they added a ball between two domes is a mystery.

just stick the ball from the Rega and see what happens.

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Re: STD 305M main bearing question

Post by Trio KD1033 » 29 Dec 2015 02:22

Copperhead wrote:
Trio KD1033 wrote:That sealant is really hard! I might have a go at it though.
One thing I have discovered by looking inside the bearing through my camera, while moving it from side to side is that the centre of the raised area definitely has a circular recess. That means that the dimple worn into the spindle was made by something that is not there now.

Andy
As Alec pointed out, the sealant is probably epoxy, the stuff is a pain to remove and heat (around 200 degrees) is one of the only things which will break it down. You will have to drill out as much as you can and pick away at the rest. If you are intending to try heating it, make sure there is nothing likely to melt. Unlucky it wasn't the new Araldite Rapid, the stuff never hardens more than a bogey.

Are you sure it is domed? Garrard 301/401 bearings have a domed thrust pad, but then the spindle runs straight on that. The dome is a type of phosphor bronze and provides the sacrificial surface, which can be replaced.

The dimples in both surfaces of your bearing are there to locate the spindle. Without them, and in a bearing which exhibits play, the spindle would not be able to stay centred.

Personally, I would polish the bottom of that spindle and do away with the leaning tower of Pisa by using a Delrin thrustpad.

A ball which fits tightly in the well will ensure it doesn't move around, it will also sit on the dimple, whether the dimple on the bottom of that spindle would stop it from moving around is debatable. I reckon a smaller ball would have a better chance as it would sit in the dimples more firmly. Why they added a ball between two domes is a mystery.

just stick the ball from the Rega and see what happens.
The Rega ball was too large unfortunately. The spindle sat too high, and the base of the spindle didn't connect with the lower bushing so there was huge play. There is definitely a recess in the middle of the dome, but it is really small. I could try what you said with the thrust pad. Is that material easy to obtain and fashion?

Cheers
Andy

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Re: STD 305M main bearing question

Post by Copperhead » 29 Dec 2015 03:20

Trio KD1033 wrote:
Copperhead wrote:
Trio KD1033 wrote:That sealant is really hard! I might have a go at it though.
One thing I have discovered by looking inside the bearing through my camera, while moving it from side to side is that the centre of the raised area definitely has a circular recess. That means that the dimple worn into the spindle was made by something that is not there now.

Andy
As Alec pointed out, the sealant is probably epoxy, the stuff is a pain to remove and heat (around 200 degrees) is one of the only things which will break it down. You will have to drill out as much as you can and pick away at the rest. If you are intending to try heating it, make sure there is nothing likely to melt. Unlucky it wasn't the new Araldite Rapid, the stuff never hardens more than a bogey.

Are you sure it is domed? Garrard 301/401 bearings have a domed thrust pad, but then the spindle runs straight on that. The dome is a type of phosphor bronze and provides the sacrificial surface, which can be replaced.

The dimples in both surfaces of your bearing are there to locate the spindle. Without them, and in a bearing which exhibits play, the spindle would not be able to stay centred.

Personally, I would polish the bottom of that spindle and do away with the leaning tower of Pisa by using a Delrin thrustpad.

A ball which fits tightly in the well will ensure it doesn't move around, it will also sit on the dimple, whether the dimple on the bottom of that spindle would stop it from moving around is debatable. I reckon a smaller ball would have a better chance as it would sit in the dimples more firmly. Why they added a ball between two domes is a mystery.

just stick the ball from the Rega and see what happens.
The Rega ball was too large unfortunately. The spindle sat too high, and the base of the spindle didn't connect with the lower bushing so there was huge play. There is definitely a recess in the middle of the dome, but it is really small. I could try what you said with the thrust pad. Is that material easy to obtain and fashion?

Cheers
Andy
Strange, the ball in the photo of the working bearing looks bigger than the Rega's. Maybe there were different designs.

The dimples would locate a smaller ball more easily, I assume.

The Delrin can be bought in rods, then cut to size, POM would probably work better. Difficult to say, it depends on the weight of the platter. You would need to experiment.
Meanwhile, why not go to the local bicycle shop and get a handful of balls!

You obviously need something smaller then the Rega's.

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Re: STD 305M main bearing question

Post by Trio KD1033 » 29 Dec 2015 03:37

Next step: smaller balls!
I'm guessing an old Scottish turntable would use imperial sizes, so I'll get 5/32" 1/8" and 3/32" aka 3.97mm, 3.18mm and 2.38mm. They seem like tiny sizes but let's give it a go.

Andy

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Re: STD 305M main bearing question

Post by jives11 » 29 Dec 2015 09:34

1/8" is what the pioneer PL12D uses. I agree looks like a Lenco bearing with an open sleeve, circlip holding a metal plate on top of which is a plastic thrust pad. As Copperhead says, the ball bearing sits in captive a recess on the end of the spindle, and rotates on the pad not on the spindle. On the Lenco there is a plastic cap which theoretically seals the oil but doesn't so a big blob of lithium grease on the underside keeps mine oil-tight. Slightly odd that they go to the trouble of having apparently serviceable parts then sealing it all in epoxy ? Is it worth soaking it in boiling water, see if that wad comes out ?

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Re: STD 305M main bearing question

Post by Trio KD1033 » 29 Dec 2015 10:57

jives11 wrote:1/8" is what the pioneer PL12D uses. I agree looks like a Lenco bearing with an open sleeve, circlip holding a metal plate on top of which is a plastic thrust pad. As Copperhead says, the ball bearing sits in captive a recess on the end of the spindle, and rotates on the pad not on the spindle. On the Lenco there is a plastic cap which theoretically seals the oil but doesn't so a big blob of lithium grease on the underside keeps mine oil-tight. Slightly odd that they go to the trouble of having apparently serviceable parts then sealing it all in epoxy ? Is it worth soaking it in boiling water, see if that wad comes out ?
I'm very tempted to really see what's going on in there. What's the worst that could happen? I like to know how things work rather than just guess.

Andy

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Re: STD 305M main bearing question

Post by jives11 » 29 Dec 2015 12:16

well if you did manage to get that sealant out you'll need a circlip tool, and I found for the Lenco ,that most sold in the UK need filing down to get the pins small enough to get in the holes. if you need to borrow a circlip tool, modified for a Lenco let me know. of course the STD may have bigger holes.

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Re: STD 305M main bearing question

Post by Copperhead » 29 Dec 2015 13:23

Hot water will make it squeaky clean but will not affect the epoxy, it takes around 200 degrees to start softening, the old stuff might just burn! Drilling and digging it out is going to be the only solution.