So what are "rifle bearings"?

[graham-xrf]

The context is cooling fans, like in the computer, or on the back panel of an oscilloscope.
Various 120mm cooling fans for computer and electronic equipment can have bearing types ball, fluid, hydraulic, magnetic, rifle, sleeve, and maybe others.
An eBay search had rifle bearings as the second most offered (132), compared to the most being fluid bearings (142).
I tried the AI engine (perplexity), but it ended up "perplexed". It had no idea!
I am looking for quiet, good flow 80-100CFM, 120mm, 12Volt, and not have to run 3 blades at 3000RPM, like the raucous Muffin fan I seek to replace. I would like to know how they compare.

In advance, I admit I don't know the connection to rifles, and I suspect folk here who are into rifles might wonder if there ever was one with "bearings", but I could be wrong!

 

[rabler]

Just a "shot in the dark", but maybe rifled (grooved) sleeves, with some lubricant?

 

[Karl_T]

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www.tomshardware.com

 

[graham-xrf]

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That is a good link!. The kind one can get distracted into.

In the meantime, I have finally discovered what it is about rifle bearings. I have seen that trick before on a generator crankshaft. The little spiral groove that stops short of the end of the bearing. It carries oil along the shaft with a little "pump" action like Archimedian screw. Otherwise, it's like a normal sleeve bearing except quieter, and have almost as much lifespan as ball bearings. They can also be mounted horizontally. We may possibly come across them on our machines in places.

I have wondered whether there is much mileage in fitting up two "quiet" fans" in series.

 

[MrWhoopee]

In the meantime, I have finally discovered what it is about rifle bearings. I have seen that trick before on a generator crankshaft. The little spiral groove that stops short of the end of the bearing. It carries oil along the shaft with a little "pump" action like Archimedian screw.

We used to do those grooves manually. Using a boring bar with a large radius tool, set a hard stop at each end of travel to prevent break out. With the lathe set to very low rpm, start the lathe, with the carriage against one stop plunge the tool to make a groove, move carriage rapidly to the other stop, allow to dwell, then move carriage back rapidly back to the other stop. Not perfect, but functional

 

[pontiac428]

If you want a quality, quiet fan with a heap of proprietary engineering, just go with a 120mm Noctua and enjoy the silence.

 

[benmychree]

We used to do those grooves manually. Using a boring bar with a large radius tool, set a hard stop at each end of travel to prevent break out. With the lathe set to very low rpm, start the lathe, with the carriage against one stop plunge the tool to make a groove, move carriage rapidly to the other stop, allow to dwell, then move carriage back rapidly back to the other stop. Not perfect, but functional

I used to do that on a Monarch toolroom lathe with reverse to the lead screw on the carriage and set stops that kicked the screw into neutral at the ends, it worked slick.

 

[graham-xrf]

We used to do those grooves manually. Using a boring bar with a large radius tool, set a hard stop at each end of travel to prevent break out. With the lathe set to very low rpm, start the lathe, with the carriage against one stop plunge the tool to make a groove, move carriage rapidly to the other stop, allow to dwell, then move carriage back rapidly back to the other stop. Not perfect, but functional

That action is about skill, and the confidence of experience! What you describe is a one-shot "get it right first time" manual move of the carriage. It has the good side in that unlike cutting driven by a lead screw, you can feel the stop, and no danger of crashing it. I take it there is a dwell at both ends of the spiral.

John's method seems a version of the more stress-free Joe Pieczynski method driving in reverse, and it needs a lathe with the trick stops to let go of the lead screw.

I guess the way these work is the spiral carries the oil along to be all over the bearing surface, and then, there would be the normal continuous loss coming out of the journal in the usual way.

I am curious about the move back, "rapidly to the other stop". Do you keep the tool cutting during this return move, making a kind of flyback fast helix? Also. in passing, how deep does one usually make the groove?

 

[pdentrem]

I have cut lube grooves free hand using a Dremel/Foredom like tool and a cutting burr. Of course the bearings were 2.5” ID!
Pierre

 

[FOMOGO]

Rifled bearings? That's when your gun is so big you have to put wheels on it. Mike