"Well,
I have decided to try my hand at painting with a gun but I had a few quick questions:
1) About how much paint per coat does it take? I am trying to decide between a full size gun and a detail gun. The main one I am considering is LVLP as my compressor has 6cfm at 90 (9 @ 40). I am planning on doing the sides, fender and hood at 3 separate times based on paint needed.
2) Drying time for primer and paint with hardener?
3) Can you paint over rattle can primer with regular primer and paint? I will use the same brand of paint (in this case JD)"
LVLP - Low Volume Low Pressure guns are great for homeowner compressors (low cfm) and new painters. They don't throw a lot of paint, so you don't have to move the gun as fast. If you are planning on spraying acrylic enamel, you need to go slow enough that you don't get dry spray, and not so slow that you get runs and sags. When I spray tractors I like using my detail gun, but I have a stable of 6 or so to choose from. As far as doing the large parts in different stages, you really should try to get them prepped & primed and then spray at the same time. This will help with a consistent finish. (weather will be the same, paint mix will be the same, your spraying will be the same) Yes, you can paint over rattle can primer as long as your prep work is excellent, but your paint is only as good as what's under it.
I use a 2 part epoxy primer. I can shoot color between 1/2 hour and 2 hours of priming without having to scuff it up. If I'm not spraying color for a day or two, I'll scuff up the primer with some 220, wipe with wax & grease remover, tack and then spray. Whatever paint or primer you plan on spraying you really need to get the "P" sheets. They detail out the mix, drying times, recoat times, etc.
The way I do it:
Clean with soap/water and/or pressure wash parts.
Wipe down all parts with Wax & Grease Remover
Grind/sandblast/sand all rust or pitting to bright metal.
Treat bare metal with a metal prep (rust convertor)
Prime with epoxy primer
Do any filler work necessary
Re-prime
Paint (I like Acrylic Urethanes as they are less finicky about the weather and the mixes are simple)
One last thing, respiratory protection. I use a fresh air system (now) and wouldn't recommend spraying without one. Cartridge masks are ok, if they fit properly and have new cartridges, but usually don't do either. My system was around $400 (Neoterik) and I've never felt better after spraying.
Good Luck.