As a side project, I'm currently in the process of building a CNC machine, and one of my major concerns is rust forming on the guide bearings. These bearings serve as wheels, with their ODs running on an aluminum rail. Now, since the bearing is rolling along this rail, I'm not sure that simply coating it in grease will work, lest it just squeeze out every time the bearing turns; so I'm curious if anyone here has a good long-term method for preventing rust on a load bearing surface. (side note, this machine will be used to cut wood as well as metal, so dust-proof solutions would be much preferred)
Only thing I can think of is dry teflon spray if you can find it.
One thing for sure, any kind of lube on a metal to metal rolling surface isn't a good idea; it will make the wheels skid. I guess your application is low speed and low load, right? Have you thought about stainless steel bearings? They're fairly common in the food processing industry.
Air conditioning.
I have, and I'm ordering a few parts from McMaster, such as ACME lead screws, but stainless steel bearings are 32 bucks a pop, and I need 24 of them. I'm trying to keep this super cheap, and that more than quadruples the cost of my hardware. I'm getting a few acetal bearings w/ stainless balls to support the lead screws, which are a significantly more reasonable 5.82 each, but with a load capacity of 55 lbs I'm not sure that is enough for the guide rails. I've already got some skate bearings from amazon, 16 bucks for a pack of 30, and built a test rig about two months ago to make sure my idea for the guide rails would work (the answer: surprisingly well), and its already developing tiny rust spots from sitting in my basement, where the machine will sit when it is complete. This machine is kind of a test, to experiment with the building techniques and controlling it, and eventually it will build its own replacement, so while I'm not willing to spend thousands on it, I do want to make it last. In a perfect world I would make some "tires" on my lathe from stainless tube and press-fit them on the bearings, but I don't have a lathe. Now I'm wondering, what about painting the OD with shellac?
Shellac will not be hard enough and will cause other problems later on... have you thought about using one of the online machine shops for making the SS tires you mentioned? on some of my cnc setups I have made with regular steel I just hit em with a shot of wd40/pb blaster once in a while to keep things from rusting up as they are in a basement garage without heat, works ok to keep things cheap.
I looked into a local shop Ronsii, and they want over a hundred bucks to make all 24, understandable, so I've decided I'm just going to live with it, maybe as you said hit it with some wd40 occasionally, and on mark two sometime in the future, I'll look into more expensive long term solutions such as full stainless bearings and lead screws.
Delmer's suggestion is a good one. That basement must have a high level of humidity. If air-conditioning isn't an option consider a stand-alone dehumidifier.