6001 Bearing - Actual Size

[wafter]

That's a good shout.

In imperial:

Bore size: 0.5" (0.50236"; ≈ 1/2")
Outer diameter: 1 1/8"
8mm: 5/16"

On edit, these maybe?
On second edit: After measuring several times again, the axle is about 12.65 mm which is within 2/1000 of half an inch.

@wafter I think you've just saved me from an expensive mistake. Thank you.

No worries - glad to help

 

[gbb]

We almost always specified " 2RS " for our stock bearings ( 2 RS = 2 rubber coated shields ). That way we could flip one or both shields out if necessary, or to clean out and repack with a specialist grease. What always amazed me was how little grease was in the bearings, even the larger ones ( palm of your hand size etc ), to the extent that I thought " this can't be right " I did query this with the SKF rep once, and he sent me some in house research that showed the vast majority of premature bearing failure was over greasing.

One of my last projects at work was a cost comparison ,/analysis of 'normal bearing maintenance (greasing) and fitting high quality sealed for life bearings.
These were industrial self aligning bearings, a bit bigger than 6001s but not massively. Using FAGs technical recommendations, the annual grease refill requirement was a mere 6g per annum in clean dry ambient, light use applications.

Just 6g per year in an industrial environment.

Overgreasing is indeed not beneficial for bearings

 

[wafter]

One of my last projects at work was a cost comparison ,/analysis of 'normal bearing maintenance (greasing) and fitting high quality sealed for life bearings.
These were industrial self aligning bearings, a bit bigger than 6001s but not massively. Using FAGs technical recommendations, the annual grease refill requirement was a mere 6g per annum in clean dry ambient, light use applications.

Just 6g per year in an industrial environment.

Overgreasing is indeed not beneficial for bearings

What's the mechanism by which excess grease proves detrimental to service life?

 

[Tenkaykev]

What's the mechanism by which excess grease proves detrimental to service life?

"
Over greasing a bearing can lead to a myriad of issues that can compromise its effectiveness.

In roller and ball bearings, an excess of lubricant may cause the rollers and balls to slide rather than roll, severely hampering the effectiveness and efficiency of the bearing.

Having the correct amount of free space in a bearing is essential to prevent churning, a condition where the bearing will needlessly be forced to operate through the excess grease. When a bearing is over greased, churning will quickly degrade the grease which can lead to overheating, resulting in premature wear and failure of the bearing and application. Chronic bearing failures can lead to large financial costs from repairs and downtime.

Excessive grease can also generate too much pressure inside the bearing. If the bearing has a seal component, the high pressure may cause seal failure or blow the seal altogether, resulting in bearing leakage and ultimately premature bearing failure."

 

[Gillstay]

"
Over greasing a bearing can lead to a myriad of issues that can compromise its effectiveness.

In roller and ball bearings, an excess of lubricant may cause the rollers and balls to slide rather than roll, severely hampering the effectiveness and efficiency of the bearing.

Having the correct amount of free space in a bearing is essential to prevent churning, a condition where the bearing will needlessly be forced to operate through the excess grease. When a bearing is over greased, churning will quickly degrade the grease which can lead to overheating, resulting in premature wear and failure of the bearing and application. Chronic bearing failures can lead to large financial costs from repairs and downtime.

Excessive grease can also generate too much pressure inside the bearing. If the bearing has a seal component, the high pressure may cause seal failure or blow the seal altogether, resulting in bearing leakage and ultimately premature bearing failure."

Very useful to know. Shame a younger me did not know.

 

[raleighnut]

Very useful to know. Shame a younger me did not know.

Yeah but bearings on cycles ain't exactly whizzing round. On an 'overhead router' (Wood work machine) where the spindle is turning at 15,000 to 18,000 or even 20,000 rpm overheating could well be a problem but what looks like grease ports on the bearings is actually an oil port and some of those machines have been running daily for 70 odd years without failing.

 

[Ajax Bay]

At 30pmh a cycle wheel (622) turns at about 6Hz (360rpm).

 

[Tenkaykev]

Yeah but bearings on cycles ain't exactly whizzing round. On an 'overhead router' (Wood work machine) where the spindle is turning at 15,000 to 18,000 or even 20,000 rpm overheating could well be a problem but what looks like grease ports on the bearings is actually an oil port and some of those machines have been running daily for 70 odd years without failing.

If it's an oil lubricated bearing there's usually either a small sprung flip up cap for adding oil, or a small sprung ball that is depressed by the nozzle of the oil can. This leads to a labyrinthine chamber filled with fabric ( often felt ) which wraps around the semi porous metal of the " sleeve " bearing.
I've worked on motors that use oil baths to keep the bearings lubricated. The top of the sleeve bearing has a narrow slot cut in it in which runs a metal lubricating ring, the top of the ring is in contact with the rotating shaft which imparts enough force for the ring to slowly rotate drawing oil from the oil bath which keeps the faces lubricated.
Still quite a few of them around. Among the ones I have worked on are the Cliff Lifts that run on rails from the Prom to the Overcliff in Bournemouth/ Poole ( motors over 120 years old, one of the motors with original bearings, the second had a lubrication mishap a decade or more ago ). Similar systems used in Church Organs, the larger ones found in Cathedrals still going strong, the mechanical speed controls being a work of Victorian ingenuity.

 

[wafter]

"
Over greasing a bearing can lead to a myriad of issues that can compromise its effectiveness.

In roller and ball bearings, an excess of lubricant may cause the rollers and balls to slide rather than roll, severely hampering the effectiveness and efficiency of the bearing.

Having the correct amount of free space in a bearing is essential to prevent churning, a condition where the bearing will needlessly be forced to operate through the excess grease. When a bearing is over greased, churning will quickly degrade the grease which can lead to overheating, resulting in premature wear and failure of the bearing and application. Chronic bearing failures can lead to large financial costs from repairs and downtime.

Excessive grease can also generate too much pressure inside the bearing. If the bearing has a seal component, the high pressure may cause seal failure or blow the seal altogether, resulting in bearing leakage and ultimately premature bearing failure."

Cool, thanks - makes sense.

I guess the slidy / rolly issue is really the only one that's of significance to us given the relatively modest speeds and operating times involved.

 

[raleighnut]

If it's an oil lubricated bearing there's usually either a small sprung flip up cap for adding oil, or a small sprung ball that is depressed by the nozzle of the oil can. This leads to a labyrinthine chamber filled with fabric ( often felt ) which wraps around the semi porous metal of the " sleeve " bearing.
I've worked on motors that use oil baths to keep the bearings lubricated. The top of the sleeve bearing has a narrow slot cut in it in which runs a metal lubricating ring, the top of the ring is in contact with the rotating shaft which imparts enough force for the ring to slowly rotate drawing oil from the oil bath which keeps the faces lubricated.
Still quite a few of them around. Among the ones I have worked on are the Cliff Lifts that run on rails from the Prom to the Overcliff in Bournemouth/ Poole ( motors over 120 years old, one of the motors with original bearings, the second had a lubrication mishap a decade or more ago ). Similar systems used in Church Organs, the larger ones found in Cathedrals still going strong, the mechanical speed controls being a work of Victorian ingenuity.

The overhead router uses a pretty standard 3 phase motor (2 hp or so) but it has a special trick, in the base of the machine is a frequency shifter this is essentially a motor that drives an alternator wound to put out 3 phase at much higher than 50hz enabling the cutter motor to rotate at 20,000 rpm or even higher (I've worked some that run at 22,000rpm) they often have 2 speeds controlled by using different windings on the frequency shifter to cope with larger cutters (generally 15,000)
The oil ports (one at the top and one at the bottom) do have the sprung ball bearing type of aperture.

 

[Tenkaykev]

The overhead router uses a pretty standard 3 phase motor (2 hp or so) but it has a special trick, in the base of the machine is a frequency shifter this is essentially a motor that drives an alternator wound to put out 3 phase at much higher than 50hz enabling the cutter motor to rotate at 20,000 rpm or even higher (I've worked some that run at 22,000rpm) they often have 2 speeds controlled by using different windings on the frequency shifter to cope with larger cutters (generally 15,000)
The oil ports (one at the top and one at the bottom) do have the sprung ball bearing type of aperture.

I'm familiar with those types of systems, I've done some work on in flight refuelling systems that tend to use HF ( 400 Hz )
We've strayed a bit from the OP bearing query, I find the topic interesting having worked " hands on " for about 50 years, not sure about the rest of the community 😁

 

[gbb]

As has been discussed above, of course bicycle bearings are low rpm, relatively low load and grease 'overloading' may only have a negligable effect...but equally may help prevent water ingress.
Nevertheless, good practice is the way I prefer to go. I'm even quite happy to remove the seal, clean the bearing out and regrease occasionally.
At the end of the day it's a bike bearing, not a motor that's rotating at 1700 rpm etc.

One thing worth considering when buying your own bearings are ones with 'low friction' seals...I've used them and they do make a noticeable difference when freewheeling.