Well you got the first part down. How to spray a finish. That's a great start, and you'll need it.
I've built and repainted many machine tools over the years. Here's some of what I've learned for whatever it's worth.
Of course it depends on what you're dealing with and what your plans are with it. Personally I would not go through this much work for anything other then something I was keeping for use by myself.
The heavy cast iron stuff:
Parts like the main castings that you don't trust others to handle properly or doubt they have the equipment to do so is where your skills are needed. Keep it in house and spray it both with a good primer and I suggest a two part urethane. They're bullet proof against any and everything you throw at or on a machine tool. Sure there are isocyanates to deal with. An air supplied hood is technically what you need, but if you're not in business and using it all the time you'll be fine. Just keep the concentrations down. You'll find these paints at industrial paint supply stores. And yes I use a standard air compressor type HVLP but you'll need biggish tips.
Prepping cast iron for paint can come in many forms. Mostly in the way of elbow grease. There is a place for solvents and plain ole hot soapy water. (Meaning Dawn dish soap.) Fabulous Cleaner at the Dollar Store is good and cheap to use also. I'll always finish with hot Dawn water as my last clean before paint. (Even back in the day before rebuilding automotive engines.) Dry it off quick and don't get too worried about the small bit of flash rust. Even after heavy cleaning most cast iron will likely leach oil. You'll see wet spots in your primer after a day or two of sitting. There's very little you can do about it unless you want to bake it all out in an oven. I also use Acryl Clean (PPG?) after primer as a last wipe off before paint. I also like spraying sealers over old paints.
The sheet metal:
A full on CNC enclosure is best done by sending it all out to have the paint burnt off. No pre-cleaning necessary. It does a great job, and believe it or not is totally environmentally friendly. The after wash they use sets the panels up perfectly for what you should do next. Powder coating. Again Urethane. For what you end up with, I find the costs to be totally worth the tons of work it saves. Plus you get a finish that is very difficult to match at home both in look and reliability. Do all the bodywork before you send it out. The great thing about this process is it is little work with perfect, near bullet proof long lasting results.
The other stuff:
Cabinet blast everything you can. (Walnut shell, glass bead, Black Beauty (Coal slag)) I never use sand anymore. Scares me more then the isocyanates. :-) The front clam shell opening cabinet types are best for dealing with large heavy pieces. Much easier to load parts in and out. I also powder coat everything I can except like I mentioned above. It's simply the best, and I've tried the rest. I use the same two part Urethane like on the other. Let's face it. Painting is a lot of hard and smelly work that can also disturb the neighbors, so why not use the best you can or at least best you can afford.
Add Edit: Sometimes for small stuff I have used spray can Self Etching Primer with a top coat. Try to find Krylon over Rust-Oleum. I hate that stuff. Tips clog. And your newborn will be graduating high school before it fully drys. I've also had good luck painting gearbox and machine cabinet interiors with light colored Epoxy out of the can. Works well in that situation. Plus the light color helps see inside when you need to.
Misc:
A large tote completely sawed in half makes a great pallet jack-able wash tank with a cover for large parts and castings. A cow watering trough makes a great rinse tank. Both cheap to find on CL. Move your heavy stuff in and out with a hoist if you have or a cherry picker. The textured finishes mentioned limit your selection a little and are more prone to operator error then the plain types, yet those in the business should have experience with it. I've stuck with smooth gloss on everything. I painted a couple of my first machines with quart cans of enamel from Menards. Total crap paint jobs. Never did that again.
Final tip.
Don't waste your time blowing holes, threaded or otherwise, with the tip of any standard air gun. You're completely wasting your time. Get a cheap changeable tip air gun with the different length small tube tips that fit down
inside the hole. I spent years blowing out holes with a standard gun thinking I was actually doing good. Ha-ha... what a joke. You'll realize the no-bull-here when you use what actually does work.
Here are some pictures of the wash tub, rinse tub with a tool changer casting, and the main castings of the last machine I rebuilt showing the main castings painted in house. What you can't see is the other half of the tote that fits perfectly over this one as a cover.
Final note. This tote with $300 worth of industrial water based cleaner in it is free for anyone near Saint Paul, MN. Even if you just want to pump it out into your own container. Looks dirty, but there is plenty of miles left in it, and any particulates are all settled out. The cow trough is for sale at 30 bucks. Decided that I've rebuilt my last machine tool so am looking to move them out. Haven't yet bothered advertising until I just thought of it now.
Hope at least part of this helps or gives you ideas. Good luck.
Dave
View attachment 275243View attachment 275244View attachment 275245