Stuart 10V Big-End Bearing Lubrication?

[Dr_GMJNParticipant @dr_gmjn]

[Dr_GMJNParticipant @dr_gmjn]

Guys – as you all probably know, there’s no defined method of directly lubricating the big-end bearing on the Stuart 10V.

I’m thinking of drilling a 1.5 mm hole from the curved base of the forked little end, all the way down to break through into the big end journal. I’d use a centre drill to form a v-shaped cup at the top. It’s not assembled yet, so would be a two minute job on the mill.

My thoughts are that I could then easily fill the connecting rod with oil, and it would lubricate the crank pin during a run.

Drawback is that any debris or wear particles from the crosshead/pin would also get directed straight down there.

Worth it? Not worth it? Any thoughts welcome. Thanks.

[JasonBModerator @jasonb]

Unless you are going to be doing extended runs probably not worth doing.

However you could drill in from the side of the conrod at an angle which I have seen on full size and replicated here

A similar arrangement but with an oil cup on this one of mine, you could simplify it by just turning a "funnel", bending the spout and poking it into a suitable oil hole.

A "Greaser" fitted to the bottom of the bearing cap would also work but a bit of a pain to get to. Greasers are a bit like an oil cup but they have a flatter base that is threaded externally for a "cup" that is filled with grease and then screwed on. You tighten the cap every so often and it squeezes out a bit more grease

[Dr_GMJNParticipant @dr_gmjn]

Thanks Jason. It won’t be run for extended times, so I’ll leave it. It was just that the cheek bosses are a very close running fit against the crank webs, and it’s capillary action alone that will lubricate the big end bearing. Seems odd that the main bearings have provision for oiling, but not the more highly loaded pin.

[mechman48Participant @mechman48]

Hi, as you mentioned you won't be running it for any extended period so I wouldn't worry about it. My S10V is only for display, as my other models, so it rarely runs for any period longer than a couple of minutes to keep things free. When I give my models a run, on air, I generally put a few drops of lube oil in the crankshaft cups ( home made ) & drop a few drips down the cheeks of the big end & let capilliary action do the rest.

George.

[not done it yetParticipant @notdoneityet]

One (full size) crank I have is lubricated from the end of the shaft. Drilled through the shaft and crank web, then cross drilled for the big end lube using a grease cap on the end of the crank. Simply occasionally grabbing the cap, to turn it a bit, was likely the usual modus operandi back in the day!

[Dr_GMJNParticipant @dr_gmjn]

Thanks guys. I'm going to leave it as-is. Firstly I don't want to risk damaging the connecting rod, and secondly, as suggested, there's no point since it'll only be run occasionally on air. It just seemed like a bit of an omission from a design point of view, and as a design engineer myself, it niggled me a bit.

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