Oiling holes?

[kvom]

Wondering if there are any rules of thumb for the size of holes  to make for oiling bearings via oilers or cups.

On my Joy engine the plans specify a 1/16 hole for some smaller bearings, but no dimensions are given for oiling the main (crankshaft) bearings.  These have a 3/4" bore and are about 1.6" wide.

I am planning to use the same medium spindle oil I use on the mills and lathe.

[Dave Otto]

I think 1/6" may be a little small for the mains; I took a look at one of my antique engines and the oil holes vary based on the size of the shaft. See in the picture the oil hole for the push rod is 1/8" and the shaft is 1/2" On the rocker arm which has a much larger shaft (probably on the order of 3/4") the hole is 3/16". The depression also varies depending on the size of the hole.

Dave

[b.lindsey]

You guys are probably used to using larger shaft sizes than I am but 1/16" sounds big to me. Why not run a quick test with the oil you plan to use with various hole sizes (maybe a couple of sizes either side of 1/16" and see how the oil flows through it. As long as it flows to the bearing/shaft interface the flow should be enough to provide adequate lubrication.

Bill

[90LX_Notch]

That's a great question.  It's something that I've never considered.  I'm very interested in what the actual engineering answer would be.

-Bob

[Jo]

The rate of oiling should be adjustable on a drip oiler in which case the size of the hole underneath is irrelevant.

If your plan is to use total drain cups, then the drain rate is caused by the amount of space between the shaft and the bearing. A 1.6mm diameter oil hole is likely to be much larger than the gap between the shaft and its bearing.

[On my Cowells lathe it has a total loss headstock oil system with a dimple for oil and a 2mm hole. A single drip of thin oil is adequate to run it for 30 mins before it needs another drip of oil.]

Jo
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P.S. Saying the Cowell headstock is a total loss system it is bit of a fib, I know exactly where the oil is: most of it is up the wall behind the lathe 

[Jasonb]

Put in a 1/8" hole and pack with worstead wool, the wool will control the flow rate. If they are oil boxes then use a slightly larger hole and press in a tube to stand proud of te oil box base. Again use tha wool and drape it over into the oil, the capilary action will draw the oil up and down to teh bearing, more strands = more oil flow

[Jo]

And with wick oilers don't forget to make a cap or some means that can be sealed off otherwise they will continue to wick all the oil out of the cup, through the bearings and all over the place  .

Cotton wicks also work 

Jo

[Ian S C]

On bigger machinery, a bit of pipe cleaner(twisted wire with furry bristles, smokers pipe), works well, easy to put in and out of the hole.

[Allen Smithee]

P.S. Saying the Cowell headstock is a total loss system it is bit of a fib, I know exactly where the oil is: most of it is up the wall behind the lathe 

So it's a non-scavanged oil system with integrated total-loss wallpaper capability.

PDR

[kvom]

Good info here.  My tentative plan is to use adjustable oilers on the main bearings and cups on the smaller ones; this is the same system that Lee used on his.  Given that most models will be run very intermittently means that much of this is probably irrelevant.