On 15/08/2010 08:29, Ian Iveson wrote:
David Harris wrote:

Does anyone know what this is /likely/ to be:

http://www.roksan.co.uk/roksan/roksanpage.php?pageno=6#

3in1, some grade of motor oil, some hybrid concoction?

I never found out what the right oil for a Garrard 401
was.
As the bearing is similar to a Roksan, according to the
pdf on that page,
then I guess the oil will be about right too.
I thought for a plain spindle on top of a ball-bearing,
something heavy like EP90 gear oil would be best.


I went the other way with my Thorens deck, and I used
sewing machine oil. Yes, I did need to top it up fairly
regularly, but it did *seem* to give less bearing noise
off the platter than a heavier oil.

I also tried PTFE spray once, but wasn't so keen.

Yes, it *is* actually important to use the right kind of
oil. The lubrication requirements of ball and plain bearings
are different, so most car or bike oils are unsuitable. The
problem here is that it's an odd application in a domestic
context. That's why the retail price is high.

Too thick, or too slippy like PTFE, STP, or molybdenum
disulphide, and the balls will skate. The surface of the oil
will be wavy so it can be a choppy ride. If a ball catches
up with its own bow wave it may briefly lock and judder.
Pressure can be great enough to crack the casing, although
not at turntable speeds.

Too runny and it won't maintain a film.

If it absorbs moisture then corrosion-erosion will lead to
early failure.

You need a thin or medium single-grade, thixotropic (or
"clingy"), water repellent, corrosion-inhibiting machine
oil, I would think. Best option, unless you already have
some of the right kind of oil, is the recommended oil from
the manufacturer, if you can get it. Maybe expensive for the
amount you get, but you'll only ever need a few drops. Share
with friends.

A plain bearing would be quieter but an oil pump would be a
problem, I suppose.

'A ball'? You mean 'The ball' It's a single ball sitting under the spindle
and only provides vertical thrust.
Sideways movement is controlled by the steel spindle in a bronze bush,
at least in the Garrard, and the Roksan diagram looks similar.
Does that change your recommendation?

--
Eiron.

'A ball'? You mean 'The ball' It's a single ball sitting
under the spindle
and only provides vertical thrust.
Sideways movement is controlled by the steel spindle in a
bronze bush,
at least in the Garrard, and the Roksan diagram looks
similar.
Does that change your recommendation?

Yes, sorry, I've had a thing about ball-race bearings ever
since motorbikes changed to plain bearings and suitable oil
for older bikes with rollers and balls disappeared.

Phosphor-bronze relies on being porous, so oil for that part
shouldn't have additives that might clog the pores, although
there's so little loading there that it might not matter
much.

If the thrust bearing isn't immersed in oil, then you do
need an oil that stays in place and makes a strong film. I
assume a ball rather than a cone is used so that an oil with
strong capillary action will be drawn in. Thicker oils and
greases aren't any better at staying in place under that
kind of pressure if there's nothing to keep the lubricant in
circulation, as there is in a gearbox or a wheel bearing.

I can't remember the tech term for capillary
crawling...something to do with surface energy...but that's
what's needed. An oil that crawls and forms a strong film
that repairs itself quickly if it breaks. To some extent,
all oils are supposed to do that, but there will be an
optimum consistency, so best go with the recommended type,
unless someone really knows better. I don't.

Not the ideal kind of bearing, seems to me, but anything
better would be lots more expensive. I would have thought
there's a risk of the contact point being off-axis.

Why isn't the plate made of nylon or PTFE, I wonder? Or even
graphite. Hmm...could be a market for audiophile oil-free
inserts.

Ian

On 15/08/2010 11:36, Ian Iveson wrote:
'A ball'? You mean 'The ball' It's a single ball sitting
under the spindle
and only provides vertical thrust.
Sideways movement is controlled by the steel spindle in a
bronze bush,
at least in the Garrard, and the Roksan diagram looks
similar.
Does that change your recommendation?

Yes, sorry, I've had a thing about ball-race bearings ever
since motorbikes changed to plain bearings and suitable oil
for older bikes with rollers and balls disappeared.

Phosphor-bronze relies on being porous, so oil for that part
shouldn't have additives that might clog the pores, although
there's so little loading there that it might not matter
much.

If the thrust bearing isn't immersed in oil, then you do
need an oil that stays in place and makes a strong film. I
assume a ball rather than a cone is used so that an oil with
strong capillary action will be drawn in. Thicker oils and
greases aren't any better at staying in place under that
kind of pressure if there's nothing to keep the lubricant in
circulation, as there is in a gearbox or a wheel bearing.

If we're still talking about a Garrard 401, the spindle and bearing are
immersed in oil;
you top it up occasionally at the top and it leaks past the gasket at
the bottom
like a good old British motorcycle engine.

--
Eiron.

Eiron wrote:

Yes, sorry, I've had a thing about ball-race bearings
ever
since motorbikes changed to plain bearings and suitable
oil
for older bikes with rollers and balls disappeared.

Phosphor-bronze relies on being porous, so oil for that
part
shouldn't have additives that might clog the pores,
although
there's so little loading there that it might not matter
much.

If the thrust bearing isn't immersed in oil, then you do
need an oil that stays in place and makes a strong film.
I
assume a ball rather than a cone is used so that an oil
with
strong capillary action will be drawn in. Thicker oils
and
greases aren't any better at staying in place under that
kind of pressure if there's nothing to keep the lubricant
in
circulation, as there is in a gearbox or a wheel bearing.

If we're still talking about a Garrard 401, the spindle
and bearing are immersed in oil;
you top it up occasionally at the top and it leaks past
the gasket at the bottom
like a good old British motorcycle engine.

:-)

Sat next to me is an AJS 500 single and Burman gearbox. The
clutch pushrod that I can see sticking out the end of the
box mainshaft has a little dent in it where it bears on a
ball. There is no provision for lubrication at all, other
than leakage. There is hardly any wear after 60 yrs. I
assume the pushrod is made of dural. The ball is steel and
it fails occasionally due to corrosion/erosion.

In that case a modern gear oil, perhaps 50 grade, would be
OK. That will be less inclined to leak, have very high film
strength, and good cold corrosion inhibition. Should last
forever. Some oils use a volatile corrosion inhibitor, good
for sealed housings when some of the parts are not immersed,
but no good in this application.

Who said that thin oil runs off? Not if it's immersed.
Grease is definitely *not* a good idea either, in that case.

Ian

In article , Eiron
wrote:


'A ball'? You mean 'The ball' It's a single ball sitting under the
spindle and only provides vertical thrust. Sideways movement is
controlled by the steel spindle in a bronze bush

Doesn't anyone use Dindsdale's 'groove pattern' to get the rotor stabilised
and floating on the oil? Not even Max Townshend?

FWIW I just used the oil that Technics supplied with my TT. Until I lost
the small tube and stopped bothering, erm, about 20 years ago. Still works
OK when I use it. No idea what it was, but if I needed some fresh oil I
guess I'd have probably used light grade oil as for sewing machines, etc.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Jim Lesurf wrote:

Doesn't anyone use Dindsdale's 'groove pattern' to get the
rotor stabilised
and floating on the oil? Not even Max Townshend?

Dinsdale? Could be a relation of mine. Dinsdales and Ivesons
come from adjacent villages in the Yorkshire dales.

You'd need a heavy oil for grooves to work at such a slow
speed, I would have thought. I've seen reference to "self
pressurising" and "floating" turntable bearings while I've
been looking around, but compared to a ball I guess the
precision machining required would be expensive.

FWIW I just used the oil that Technics supplied with my
TT. Until I lost
the small tube and stopped bothering, erm, about 20 years
ago. Still works
OK when I use it. No idea what it was, but if I needed
some fresh oil I
guess I'd have probably used light grade oil as for sewing
machines, etc.


If the last shot of oil has lasted 20 yrs and is still OK,
then if it ever needs oiling again, wouldn't it be sensible
to use the same type? By what logic might you decide to use
something else?

Ian

In article QFZ9o.13506$qQ6.7489@hurricane, Ian Iveson
wrote:
Jim Lesurf wrote:

Doesn't anyone use Dindsdale's 'groove pattern' to get the
rotor stabilised
and floating on the oil? Not even Max Townshend?

Dinsdale? Could be a relation of mine. Dinsdales and Ivesons
come from adjacent villages in the Yorkshire dales.

Pass.

You'd need a heavy oil for grooves to work at such a slow
speed, I would have thought. I've seen reference to "self
pressurising" and "floating" turntable bearings while I've
been looking around, but compared to a ball I guess the
precision machining required would be expensive.

Given the price of some modern TTs I'd have thought they could afford it.
:-)

FWIW I just used the oil that Technics supplied with my
TT. Until I lost
the small tube and stopped bothering, erm, about 20 years
ago. Still works
OK when I use it. No idea what it was, but if I needed
some fresh oil I
guess I'd have probably used light grade oil as for sewing
machines, etc.


If the last shot of oil has lasted 20 yrs and is still OK,
then if it ever needs oiling again, wouldn't it be sensible
to use the same type?

No doubt... So *if* I had any idea what "type" it was, I'd probably choose
it.

By what logic might you decide to use something else?

Only the practical reality that I have no idea what "type" it was. Using
'logic' to reach a decision also depends on your starting conditions. :-)

But as I said, I've seen no reason thus far to think it needs re-oiling. So
I have no plans to do so. Who knows, by then I may find the old tube of oil
falls out of an ancient box when I am tidying. Looking for one thing is
often a good way to find something else. ;-

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html