The topic of how I paint machine tools including the Pratt & Whitney is lengthy, but it’s the details that make a difference. I’ll break it into multiple posts to try to make it more readable.
I’m not a professional painter or paint expert. However, one of the reasons I decided to post this is that I figure many who are interested in this subject on this forum aren’t either. I generally get decent results, and I’m confident that others can too.
First thing to remember is that I consider a good paint job to be a byproduct of a refresh or a rebuild of a machine. What I mean is the quality of the paint job is proportional to the amount of disassembly done. It is easier to prep and paint small individual parts than to try to mask a large machine made up of intricate parts. When you paint a machine that is not disassembled, it can wind up with too much paint in some areas and not enough in others. This is how you get runs and overspray.
I’ll divide this into three sections: 1) Materials and tools, 2) Machine preparation, and 3) Painting.
1) Material and Tools
I’ve included some pictures of the materials I use. Through the years I’ve tried several paints but finally settled on Anchor Paint’s Saf-T-Gard I or II with a cyanalite hardener. This paint seems to be durable, relatively low cost, and easy to touch up or repaint. The hardener I use is Anchor’s Polyurethane Converter J1100. Using a hardener allows me to change ratios from an 8:1 full strength which is very hard to a 16:1 half strength which has more chip resistance.
I know some people are reluctant to use cyanalite, but if you are careful about ventilation and safety equipment, I’ve never had a problem. The one thing to keep in mind is if you miss a little part and you’ve already taken your mask off, don’t think “I’ll just shoot the one little part without a mask.” You cannot do that. Always use an appropriate respirator. I use two North half-mask respirators. One has a P100 cartridges which is used only for sanding. The other has a P100 cartridges with charcoal which is only used for painting. The reason I use charcoal version is that it removes the paint odor. If you smell paint, you’ll know you have a problem with your filter. I also use a Tyvek full white suit with hood and nitrile gloves that I get from Harbor Freight.
I use Evercoat Rage Gold filler. It is easy to sand, relatively soft, and sticks to about anything. I experimented with harder fillers, but they are harder to sand and if you drop a crescent wrench it chips it regardless of the type of filler used.
For sandpaper I use Indasa Rhynostick Rolls which I buy from Eastwood. I use 80, 120, 180, 220 and 320 grits. This sandpaper has a sticky back which can be folded over on itself making it easy to hold. It’s expensive but cuts quickly and lasts a long time.
I use either Evercoat Feather Fill primer or Eastwood High Build Self-Etching primer in aerosol cans and by the quart applied via a spray gun depending on the size of the part. This goes on after the filler work is done.
The other primer I use is Anchor Quick Dry Gray Primer which goes over the feather fill coat. This is important because the feather fill primer is porous. I use the Quick Dry Primer not only because it dries quickly, but when you paint intricate parts, it is easy to get too much primer in small areas which causes cure problems (i.e. it leaves it soft). If you spray over an uncured soft primer, you’ll get peeling or cracks. This primer helps you avoid some of those problems.
I use is Anchor J1131 Synthetic paint thinner. It works well in a variety of different temperatures and works with the primers and paint.
When I mask parts, I use low stick masking tape, box of razor blades and a full bucket of rubber and cork plugs ranging in size from about ¼” to 2” in diameter. I use these to plug holes and bearing bores. It is important to keep this paint off precision surfaces as it can be difficult to remove when dry. Also keep several rolls of round foam weather insulation. This can be put in bolt holes and cut flush with a razor blade.
The spray gun I use is a 3M Accuspray. For general painting I use the 1.4mm head and the larger heads for primers and fillers. The heads are plastic, come in different nozzle sizes and are disposable (i.e. pitch instead clean). The gun also has liners and strainer built into the disposable cups. This makes clean up very easy, requires very little solvent and allows for quick color changes. The gun is very simple to adjust. It has a fan control which I use one turn open; fluid control with 3 turns open at 20 PSI trigger down and hold. It does a remarkably high-quality job for being mostly plastic and disposable.
One other tool… Most machine tools have metal tags that are held on by little brad screws. These can be difficult to remove without destroying the tag. I use a wood chisel that has been ground down to a long, thin wedge with a small square notch in the center (1/8” x ¼”). The leading edge is sharp. This allows you to get under the tag’s edge and pry up the brad without damaging the tag. If you don’t want to damage existing filler and paint, stick a piece of poster board under the heal first. This always works. These metal tags should be removed because they are harbinger of oil, the nemesis of a good paint job.
There are four power tools I use which are a belt grinder with a medium Scotch-Brite belt, a buffer which I use with only two compounds that I keep separate on two different wheels, and a two wire buffers which I keep very soft wire wheels on. I keep all of these away from precision surfaces, but there are many other places these can be used. The power tool is a power washer as mentioned in an earlier post. I use it on bases, chip trays, beds and columns – things that all moving parts can be removed first. I usually keep it away from headstocks, saddles, aprons, those kind of things.