For those who repaint

[Patrick Kane]

How perfect does the surface need to be prepped before painting? I have a 72 cabinet im going to repaint, and i would rather not spend the time stripping the entire cabinet if i dont have to. There is flaking and rust at the base that i plan on taking a wirewheel to and cleaning up. Most threads i see guys completely sandblasting the tool, wetsanding it, priming it, and then applying paint. Last night i even found one on OWWM where someone polished a PM45 to a mirror finish. Ive never sprayed paint out of my HVLP setup, and i dont expect automotive level results. I just want it to be respectable looking. At some point it will be whacked by a cart, or a board, or something else that will ding it. Any tips on prepping before paint? I have a FUji 4 stage turbine, but ive only ever sprayed clear finishes out of it. I imagine it can handle paint with minimal thinning.

[johnny means]

Every shop I've ever painted machinery in just cleaned them lightly wire brushed before rolling and brushing on an industrial type oil based enamel.

[Don Jarvie]

I’ve used a course wire wheel on a grinder then course sandpaper on the grinder. It will get a lot of the paint off. When I redid my 74 PM 66 I got the paint off, washed with Super-clean and primed the cabinet. You can give it a quick wet sand.

I recommend auto paint. It’s easy to spray and gives a nice finish. The paint has a reducer in it and dries fast. The key is applying a hardner after you paint. The hardner will keep it from chipping. You can add the hardner to the paint or get some cans. The issue with the hardner in the paint is it’s only good for a day or two. No need to sand once you paint.

[Wayne Lomman]

For what you have there, power wire brushing and grinding/sanding to get rid of loose and flaking rust and loose paint will be OK. Sand the existing paint and feather the edges so you don't have a sharp step at the transition from paint to bare steel. Use a zinc phosphate pigmented or similar primer and a compatible top coat. Auto products are good but so are straight industrial paints. Hammer finish paints survive well on machinery like this. I can't tell you exactly what to buy as you have different products available unless you are in Australia too.

Things to avoid:

Wet sanding on bare steel. It is counterproductive when you are trying to prevent rust. You get water in gaps where it can't easily get out and the steel is going rusty before your eyes. Just don't do it. Auto guys don't seem to worry about it but they are focused on standard of finish above other considerations. I spend my time focused on corrosion protection first.

Overly fine finishing during surface preparation. Paint needs a mechanically keyed surface to hang onto. Finish your surface preparation with sharp abrasive so that you have a surface you can file your finger nails on. Not too coarse though or it will suck up too much paint. Sharp 120 grit is as far as you need to go.

Burnished surface. This leave nothing for the paint to hang onto. Its a total waste of effort and the earth's resources. Going too heavy with the power wire brush will burnish the steel as will fine sanding.

I said a bit more about painting metal in the Metalworking forum. Its only about 5 topics from the top. Cheers

[Patrick Kane]

Great, glad to hear this is universally acceptable and I’m not being lazy. When you guys wire brushed your machines, did you use brass or steel? I only have brass, which I’ve used to clean off rust off surfaces nicely. Not sure if brass is stout enough.

I was was just going to go to Sherwin Williams with the paint code off OWWM and buy whatever they suggest.

[Richard Coers]

Any paint job is only as good as the prep. Golden rule of finishing. If you don't want to spend a lot of time prepping, why paint at all? It just going to be whacked by something anyway.

[Jim Becker]

Really clean and oil free combined with a surface abraded for good adhesion should be just fine. Best to prime any areas that you did have to take to bare metal.

[Jeff Duncan]

Auto paints are nice.... but pricey! I spent way too much painting a shaper with them several years ago, but felt it was worth it for the finish I wanted. I used a 3 stage Fuji to spray and had no problems. But the paint I used was a pretty thin viscosity. You have to be careful as some industrial finishes may be higher viscosities which may need a lot of thinning to spray through the turbine. Hopefully the guys at SW can help you there.

As far as prep I removed all the loose paint and sanded whatever was left until I got it reasonable clean. Going down to bare metal is great if you can do it, but certainly not necessary. You just need to have a good intact surface to paint.

good luck,
JeffD

[johnny means]

Any paint job is only as good as the prep. Golden rule of finishing. If you don't want to spend a lot of time prepping, why paint at all? It just going to be whacked by something anyway.

Paint in a shop is often not about looking pretty.

[Patrick Kane]

Yeah, I want to clean up the rust and paint over the whole thing to prevent further rust. Aesthetics is a secondary motivator. Although, I’m trying to class the joint up a bit, so I’d like the saw to look halfway decent. I was mostly asking if I had to strip every last bit of the original paint off before repainting. Sounds like I need to strip and sand the lower 1/4 down to bare metal. The rest I was hoping to give a light orbital sanding before priming.

[Matt Day]

I’d strip it with an angle grinder with a Norton Rapid Strip wheel. Those things are by far the best IMO at stripping flat surfaces. You’ll need a wire wheel (steel not brass) for places like where the plinth meets the cabinet since that’s tough for the disc to get into.

Strip paint/rust, apply a degreased like super clean, then paint. This won’t win any contests because you skipped bondo work, but it will still look good and prevent rust.

Would be a good idea to also strip rust on and paint the inside too. I painted the inside of my Uni white to make it easier to see in there.

[William Batdorf]

I agree with the Sherwin Williams approach. Check out their line of metal shop finishes. Much less expensive than automotive paints. A full line of primers and colors geared toward metal fabricators. I've used the product numerous times with very good results. The product thins with xylene and it's very forgiving to less than perfect thinning proportions. I use a Sharpe Finex 3000 HVLP gun and it gives very good results.

[Bill Dufour]

No need to remove all the paint. If the existing paint is sticking on and hard to remove just sand it to feather the edges then paint over it. I think the tractor supply paint is fine in a shop. I thin with coleman fuel. In California we have to thin with double the recommended thinner. If you can wait a week or more after painting to let it harden.
I have mixed TS paint to get the color I wanted. Use some fast food spoons and mix like two spoons of green to one spoon of gray to see what you get. Once you get the ratio right I use a dixie cup to scoop it out of the cans and measure the ratio.
Bil lD.

[Bill Dufour]

No idea where you live but the northern hemisphere is going into winter and cooler temperatures will mean paint takes longer to dry. If you do this inside be careful as the vapors can be flammable and bad to breathe.
Bill D

[Jim Becker]

There is also the option of using "tractor" paint...and just brushing it on. It applies easily, levels nicely (it's oil based) and looks nice when done.