Need help painting a machine

[Bobby Robbinett]

Hey guys, I have a machine that I have broken down and am rebuilding at the moment. While I have it apart I want to sand it and do a repaint because the original paint is all beat up and has lots of scratches. I have painted a lot of cabinets but never anything metal. The machine’s base is cast iron and the smaller parts that I pulled off are mostly cast iron I believe as well. It’s a type of multiple head shaper sander. I initially wanted to have it sand blasted and power coated but my local guy is way busy and said it would be a month or longer before he could get to it. So I am looking for advice from you guys on sanding and painting this thing. I have worked at a cabinet shop most of my life and would consider myself a veteran of sanding and spraying cabinet coatings with a variety of paint guns.

My thoughts on sanding this beast are to use a grinder with an 80g flap wheel to hit all of the areas that are scratched and have surface rust. Then use my Festool RO125 5” ros to sand the rest of the machine starting with 120g going up to 320g. Would this be ok? I have never sanded or finished anything made of something other than wood.

My next question to you guys are what would be a good primer and paint to use? I would assume two coat of primer and two top coats would suffice. I don’t want to spend a ton of money on an automotive 2k type of finish. Just need something basic and somewhat forgiving that I can spray with cheap HVLP gun. I can find a TDS sheet on what ever primer and paint I choose for info on thinning and needle/nozzle size for my HVLP gun. Any help would be great!

[William Hodge]

Depending on the age of the machine, it might have lead paint on it. In that case, electrolysis would make less airborne lead than sanding. It's worth a lead test.

[Lisa Starr]

Look into the Createx paints. They are Waterborne and quite forgiving to work with. The only drawback is they need to have a urethane clear coat applied for durability.

[Matt Day]

I’ve restored many vintage machines.

Ditch the sandpaper and flap wheels. Use an angle grinder with wire wheel for the cast iron, and for any sheet metal use an abrasive wheel like this for on your angle grinder:
https://www.harborfreight.com/4-1-2-half-inch-nylon-abrasive-wheel-94017.html?utm_source=google&utm_medium=cpc&utm_campaign=12126402660&campaignid=12126402660&utm_content=118355062073&adsetid=118355062073&product=94017&store=441&gclid=Cj0KCQiA0eOPBhCGARIsAFIwTs5AjN2rVMa4Ot0oRAUs Dnl0NozEF5vTpuMpTeVSTjYfCxxWOgH9ojkaAsyHEALw_wcB

You don’t need to sand progressively on metal like you do in wood. Just strip the paint, clean it with mineral spirits, and prime and paint. It’s up to you if you want to do any kind of bondo to fill and deep scratches or rough castings in the CI.

Rattle can primer and paint works just fine by the way.

[Mark Hennebury]

Rust-oleum, oil-based rust paint and primer. and Automotive body filler, sandblasting is best prep. I will show you more later, in the meantime you can check out my website on the rebuilds tab. www.solidwoodmachinery.com

[Bill Dufour]

Tractor supply oil paint is pretty good stuff. In California you need to double the amount of recommended thinner to spray. In the other 49 states the label may be correct.
Bill D

[Michael Fink]

Wire wheel, primer coat (Rustoleum), color coat (Rustoleum), clear coat (2K urethane). The clear is where the hardness/protection come from, this is what I typically use for heavy equipment/tractors/etc (the same thing you'd use on a car):

https://www.amazon.com/Speedokote-Acrylic-Urethane-SMR-1150-1102-Q/dp/B00SX5537Y/ref=pd_lpo_1?pd_rd_i=B00SX5537Y&psc=1

DO NOT SPRAY THIS STUFF without a good respirator. It's a 2K urethane, breathing it in will do bad things, potentially very bad. It also smells like death. Spray it with a gravity gun using a 1.1-1.4 tip. Harbor Freight cheepy works fine if you'll only be spraying once. Honestly, if you're not going to do this much, rather than get the right thinner, I'd just throw the gun away.

[Dan Friedrichs]

While the common advice is to wipe sanded surfaces with a solvent (mineral spirits, etc), this is a really good explanation (and demonstration) of why that classic advice is incorrect: https://youtu.be/x7onZGqrYyY?t=180

[Patrick Kane]

I sprayed a machine and then i brushed and tipped another machine. Unless you are aiming for better-than-new and user automotive filler to prep the base casting as perfect as possible, then i would skip spraying and roll/brush an oil based machine paint. The cleanup from spraying an oil based paint is dreadful. Here is an Oliver 232 from last year. Zoom in on the photo and you will see the casting has imperfections all over it. This is why i say spraying is pointless if you arent going over the whole machine and filling these defects. A sheet metal machine will be a smoother base to begin with than a cast machine. Start with your goals for the machine and then follow the appropriate steps to reach those goals. While i admire guys that go the extra 10 miles on machine restorations, i personally am not on board. Case in point, i dropped the arbor nut(it weighs like 4-5oz) while changing a blade on the Oliver and the fall put a good ding in the base cabinet's paint. It is a tool, you are going to ding it, and that is why i personally wouldnt go the route of using bondo and spray equipment.

[Bill Dufour]

On the Ts paint: they sell a hardener. I think it is a expensive waste of money. Once you use any the sealed can has about a one year shelf life. It does not make the final cured paint any harder. It helps it cure faster and get harder sooner. If you can wait a week after spraying before banging on the paint you will be fine.
I do not use the special thinner sold by TS. I use coleman stove fuel off brand from walmart. Cheaper then paint thinner, less smell drys faster, higher polarity so more cleaning power. It is about 99%. naptha.
Bill D

[Brian Runau]

Best way to finish is sand blast and electroplate. If there is any way to wait I would look for this, I think you will be happier in the long run. Brian

[Jeff Monson]

If you are going this far on the restoration, I'd highly recommend staying away from any rattle can finish. Even the 2k rattle cans with activator leave alot to be desired when it comes to MIL thickness and durability. If you have any spray equipment do yourself a favor and get decent automotive style finish. If its bare metal do an epoxy primer or good 2 part primer to start with. If you are just sanding a good 2 part primer would be my choice. For your color or topcoat, you can do base and clear (which is a little overkill) or I really like the durability and ease of Utech 500 which is a tintable single stage (still a 2 part product) and do a couple coats. I have used this on many motorcycle parts, its super durable and is not affected by thinners or petroleum products. FWIW you can buy a quart of primer and a quart of utech paint from a local auto paint store for $115.00.

[Carl Beckett]

I would not sandblast unless you are taking apart every nut and bolt (and bearing).

Good recommendations above.

I have restored some old tractors - farm equipment paint is quite good. I might suggest a 2 part epoxy primer then overcoat of your choice (the tractor forums all have personal preferences). I do agree you can get a 'good enough' finish on cast surfaces with a roller/brush. For sheet metal I would spray. My experience is limited to spraying automotive urethane with hardner over 2 part epoxy. (its quite durable).

[Bobby Robbinett]

Update:

I got the machine stripped and every thing disassembled. The cast iron base has been sanded and is almost ready for primer. I took a grinder with an 80g flap wheel to all of the scratched and flakey places. Took those areas down to the bare metal. My plan is to shoot some rattle can etching primer on the bare metal spots. Then lightly sand the entire cast iron base with 320g to smooth the places that I spot primed with the rattle can etching primer.

Then I will shoot it with some rustoleum oil based clean metal primer using a green Harbor Freight HVLP gun. Sand with 320g then shoot another coat of the Rust-Oleum clean metal primer. Then sand again and shoot the creamy white Rust-Oleum oil based top coat.

This will be for the cast machine base. The entire machine has 3 different heads. One a shaper and two are sanding heads. I plan to make all of the heads components black and shoot them with black rattle can primer from Rust-Oleum and then black rattle can Rust-Oleum top coat.

Does this sound reasonable?

[Jim Becker]

Bobby, be sure that you use a decent de-greaser to insure your surface is pristine and very clean before your next steps. It's little things like that which will make the end result better and more durable.

[Bob McBreen]

There is a great thread started by Patrick Walsh about his work restoration an old Martin sliding saw. Lots of information on his prep and spraying.

[Alex Zeller]

For metal you want some light scratches for the paint to bond to. Shinny is bad when it comes to painting bare metal. 320 grit is as fine as I would go. For a shop tool I would probably use 180 or 240 grit as you are not going for the same type of finish as you would on a car. Often people use the maroon colored Scotch Brite pads (320 grit) as a final prep. For epoxy primer I've heard of people using 80 or even 60 grit and then sanding after the primer dries to smooth it out.

[Michael Fink]

If you have a gun, I'd strongly recommend going to a 2K product (like I linked above) for a top coat vs a standard rattle can. It's much, much harder and you'll get a much better (car type) final finish. It's also not that expensive if you already have a setup to spray, IIRC, it's about 80 bucks to a gallon of what I use, you'll probably only need about 16-32oz to finish your machine with 2 coats, so you'll have plenty left over for the next job (and it lasts a long time because it's a 2K product, won't harden in the can).