Bronze Bushing and Steel Lube

[ShagDog]

I have a bronze bushing on my spindle cone pulley that was used to fix the end of the cone pulley that had worn on the inside diameter. The bushing is a tight fit inside the cone pulley that spins freely around the diameter of the lathe spindle. The bushing spins around the lathe spindle when the backgear is engaged.

While looking for bolts for something totally unrelated, I came across the term "galvanic corrosion" (dissimilar metals corrosion), and found that bronze is not compatible with steel, and may cause the steel to corrode as long as there is the presence of an electrolyte (not a science mind here so not sure exactly how it all works).

Then I got to thinking how can bronze cause steel to corrode when the combination is used in many applications, even lathe bearings or bushing in the older lathes.

Then I got to thinking further that if it is an issue, then a good oil should prevent the corrosion. I was thinking a way oil equivalent to Vactra 2 would be good. The application is low speed. In back gear, it would turn no faster than 1000 rpm, much higher than I would use in backgear. The way oil would form a moisture barrier also.

Now for the questions:
1. Is galvanic corrosion (dissimilar metals corrosion) any concern in this application?

2. Is way oil good to use if there is any issue of corrosion, or in any event, in this application?

 

[benmychree]

In a word, NO! galvanic corrosion is "in the presence of an electrolyte", and there is no such substance in machine tools where oil is present. Vactra #2 is good for (nearly) any application for machine tools except for heavy gearing and precision high speed spindles. "I'd have it on my hotcakes if it tasted better", to paraphrase an old boss from long ago, with respect to white lead.

 

[JimDawson]

It's unlikely that you would have a problem in that application, unless you keep your lathe immersed in salt water.

 

[ShagDog]

It's unlikely that you would have a problem in that application, unless you keep your lathe immersed in salt water.

It's not ready for boat anchor status yet, at least not to me . Actually, it is an older lathe, Taiwanese that I have grown very fond of, and would like for it to last me forever. In any event, here is a photo of the cone pulley which is the one at the bottom of the picture. The bronze bushing is at the left hand end (under the small gear)and goes to about where the belt is. The oiling setscrew is in the middle pulley.

 

[ShagDog]

Oh, if anyone is interested in more about the lathe, here is a link to a thread I did on it: https://www.hobby-machinist.com/threads/select-lathe-model-816b.85227/#post-765245

 

[Ulma Doctor]

congrats on the new to you lathe!
you are very unlikely to get any appreciable galvanic corrosion in your lifetime.
if there were alkaline or acidic components introduced to the assembly, that would change things.

you got bigger things to worry about.....
like where do i get my hands on some 12L14, 2024 aluminum and delrin to play with!