Ball-race arm-bearings - lubrication an absolute no-no?

[Aleksunder]

'Received wisdom' seems to be that ball-races such as in Rega arms should always be left completely dry, I assume because they are open to the elements and would (sooner or later) gum-up from the ingress of air-borne contaminants.

That said, from what I can gather they would in fact function better in several ways if they were lubricated (until the aforementioned contamination offset it), such as less stiction and, more importantly, bearing rattle.

By "bearing rattle" I don't mean actual gross or audible buzzing, but rather the way they deal with noise (pops and clicks), and the overall coupling of the arm-tube to the yoke/carrier.

I'm about to clean the bearings on an elderly RB250 in-situ (probably by flushing using lighter petrol followed by isopropyl) before installing new wiring, and I'm seriously tempted to try using a suspension of very light (synthetic?) oil in the final flush.

Could anyone convince me this is a Bad Idea?

Thanks.

 

[djQUAN]

I think the notion that lubrication is a no no came up since when you add oil to an open bearing, chances are, dust will stick to the bearing and be more difficult to remove than a dry one...

 

[Aleksunder]

I think the notion that lubrication is a no no came up since when you add oil to an open bearing, chances are, dust will stick to the bearing and be more difficult to remove than a dry one...

Aye, which is exactly the point I was making.

I guess how quickly the bearings get fouled depends on the cleanliness of the environment in which they subsequently live.

I wouldn't like to try the flushing exercise I mentioned with the wiring in place, let alone the foam I'll be stuffing into the arm-tube.

 

[Nanook]

what about dry lubricants?

graphite types, or silcon based types? I live in a particularly dusty climate, and haven't had "Bullshot" bicycle grease foul up over several years (in a exposed bearing tonearm)

 

[EC8010]

I once lubricated the ball races in an SME3009mkII arm. Big mistake; they gummed three years later.

 

[AMV8]

Hi

I have used a lubricant when I rebuilt an arm bearing. I figured that watches and clocks use a very fine oil so it should be ok - and has been. However the turntable is in a cabinet so it keeps reasonably clean.

I used wd40 as the lubricant. Very fine oil and does not tend to pick up much dust. I found the arm better with wd40 than without.

Don

 

[Aleksunder]

I once lubricated the ball races in an SME3009mkII arm. Big mistake; they gummed three years later.

Was that due to dust sticking to the races, or did the oil itself gum up?

I know some oils break down over time with exposure to air and form a sticky gunge all on their own, synthetics are apparently much more stable.

A couple of the other guys have mentioned using lubes which are formulated to be minimally 'sticky'.

And did you manage to clean those bearings out?

 

[Conrad Hoffman]

It's probably a bad idea, since arms can be so tough to clean well. FWIW, I've heard of people putting WD-40 in a cup and letting it settle for a few days, then using the clear oil from the top. IMO, WD-40 is not a good lubricant. It's many things, but that's not one of them. There might be some merit in using one of the special damping greases from Nye, and their stuff is formulated not to gum up, but the cleaning issue remains. They also make some very high tech oils. Eventually, no matter what you use, it will be time for a rebuild. I often fix old cameras where the oils and greases have turned into something close to an epoxy, and it's not fun.

 

[tvi]

Never had a problem with this stuff

An externally hosted image should be here but it was not working when we last tested it.

but I haven't usesed it in a tonearm.

From here

• Won't drip, run or evaporate
• Repels dirt, dust, grit and grime

Regards
James

 

[EC8010]

I can't remember what oil I used in the SME but it wouldn't have been exotic. I got it out by removing the bearings and giving them a good soak in isopropyl alcohol. I doubt if it was dust; the SME is quite well shielded.

 

[Mark Kelly]

That said, from what I can gather they would in fact function better in several ways if they were lubricated (until the aforementioned contamination offset it), such as less stiction and, more importantly, bearing rattle.

Could anyone convince me this is a Bad Idea?

Thanks.

That would depend on how much convincing you need.

The first thing to note is that lubricating a low speed precision bearing will increase the drag in the bearing. This is why jewel bearings are always run dry - if lubricated the surface tension of the fluid creates a larger effective contact area (the pool of lubricant surrounding the contact) which increases the energy required for a given movement thus increasing the effective drag. The same applies for ball bearings.

 

[EC8010]

Thanks for the explanation. No oil for me!