Brass Technical Tips
Number Three:
December Brass List 1997
"Cleaning Methods and Lubricants"
Welcome back to Brass Technical Tips for December, 1997. This issue addresses the 'How to' and 'What to use' when you encounter the recommendations to 'clean' or 'lubricate' in these bulletins. You will note , in the following, that specific products are sometimes mentioned. This should not necessarily be construed that these are the only products that will accomplish the task at hand. It only signifies that we have had personal experience with these particular ones, and hence feel comfortable recommending them. Indeed, there are quite a variety of cleaning products available, from a number of sources, to do these jobs (e.g., electronics and automotive stores). If you find something that does a terrific job for you, go for it. Remember though, a product's ability to clean or lubricate must also be tempered with its compatibility with the material you are working with (e.g., parts made of plastic or other synthetic materials).
It is worth pointing out here, that cleaners contain solvents of some sort, and most require careful handling and use. At the very least, their vapors can be harmful to breathe. Some can be harmful from contact with the skin. In any case, it is important to read all warning labels on products before you use them and follow their advice, as well as the instructions on how they are to be used. These words are not intended to frighten you away from using such products, they are just intended to convey the message that a cautious approach is a safe approach.
Cleaning Methods and Materials:
The scope of this section addresses cleaning for reliable operation. It does not address cleaning brass in preparation for painting, a topic which has been adequately addressed already in most of the major model railroading periodicals. In essence, our discussion of cleaning will focus on electrical pickup/contact areas and mechanical/drive train areas.
For simplicity, we can treat cleaners as two basic groups: liquids and abrasives (I will consider various types of brushes as abrasives). Liquids consist of the various types of track/wheel cleaners, electronics parts cleaners, and various kinds of hardware or drugstore type solvents (e.g., mineral spirits, lacquer thinner, acetone, alcohol, etc.). Abrasives include the various kinds of sheet abrasives (wet/dry silicon carbide papers), the new handy abrasives on foamboard sticks, 'track erasers' and various types of metal and synthetic brushes. In selecting a cleaning method / material, a good rule of thumb is to use the least aggressive approach that will get the job done, be it a liquid or abrasive.
Electrical Pickup/Contact Areas
OK, with that said, let's proceed with some meat now. You are going to encounter two types of areas: those that are raw brass and those that are plated (usually with nickel silver).The raw brass areas most likely to require cleaning are electrical contact areas such as tender body and truck bolsters and on very old models, perhaps the wheels and wireless drawbar assemblies. If these are in generally good condition, with just a small accumulation of grime and oxidation, any of the commercial track cleaners or alcohol will do an adequate job, although alcohol (rubbing or denatured) may leave a slight residue when it dries. This is easily wiped off. Most of the track/wheel cleaners leave a residue that is actually an oxidation inhibitor and is conductive. On stubborn areas (bolsters) you may encounter heavy corrosion or paint. For these, the hobby sanding sticks or wet/dry silicon carbide papers are ideal, in grades of 320 and up. Clean these surfaces until bright, but be careful to sand flat on bolsters, to avoid rounding these areas and creating wobbly trucks. Brass tender drawbar pins can be cleaned the same way. The important parts to clean in a wireless drawbar are the holes for the screw and tender pin, and the side of the contact wire that touches the tender pin. For these, rotate a toothpick in the holes to burnish the brass. A fine cut round tapered file can be used, if discretion is exercised. Rotate the file LIGHTLY in the hole, in the direction so the file is trying to back out of the hole (usually counter-clockwise). You do not want to remove any material, just the dirt and oxidation. A few turns should do it. This method also has the benefit of cleaning the wire exactly where it will contact the tender pin.
If brass wheels are too corroded for a liquid cleaner to do the job, skip the abrasive stick approach - you will only risk introducing flat spots. A wire rotary brush in a rotary (Dremel) type tool is effective here. However, a brand new wire brush is usually too aggressive, because the bristles are too straight. Break it in first by cleaning a bit of scrap brass until the bristles develop a slight cant away from the direction of rotation. Operate your hand tool at somewhere between 500 and 2000 RPM and wear eye protection. Also, once you have used a wirebrush on brass (or plated brass), do not use that brush to clean other metals (especially steel), and then come back to clean brass later. The brush will pick up traces of the other metal and contaminate your brass surface and encourage corrosion. For drivers, hook up test leads to the locomotive and rotate the drivers at medium speed, with the direction of rotation against that of the rotating brush. For non-powered wheels, hold the rotating brush at a slight angle to the wheel to impart a scrubbing action, otherwise the brush is mostly just spinning the wheel. You will also notice, over time, that your brush collects dirt and will leave a greasy film on the wheel. So you have a choice of either cleaning the brush regularly or cleaning the film off the wheel, which comes off quite easily.
The plated areas that may require cleaning are usually limited to the wheels and wireless drawbar assembly. The purpose of the plating is to inhibit corrosion and hence enhance electrical conductivity, not just to look pretty. Accordingly, use of a liquid cleaner will usually be entirely adequate for these kinds of surfaces. For plated wheels, use a liquid cleaner first to get rid of the dirt and grime build-up. Then, if the wheel tread surface is scored or abraded from use, these areas may be restored by a light polish with a broken-in wire brush in a rotary tool, as described above. This may be followed by a rotating bristle brush in the same tool. The goal here is to restore the surface as close to its original smoothness as possible. The smoother the surface of wheel treads, the less likely they will be to attract and pick up dirt and grime from the rails. Yes, a highly polished wheel tread may have a bit less traction, but the electrical conductivity and pickup benefits make for a net gain. Obviously, it is not necessary to polish the insulated drivers to the same degree; these just should be clean.
Plated wireless drawbars can usually be cleaned quite nicely with a liquid cleaner. Use a pipe cleaner or toothpick to clean the holes for the screw and tender pin. Rotating a toothpick in these holes will usually impart a nice polish. A note here on painting wireless drawbars: Their surfaces can be painted to make them 'disappear', without spoiling their electrical conductivity, as long as the tender pin hole, the contact wire where it touches the pin, and the hole and surface for the attaching screw and spring are all unpainted and bright.
In general, it is best to shy away from abrasive sheets or sticks to clean plated surfaces. If such a surface is unusually corroded, use a very fine grit, 400 or higher. You want to remove the corrosion, but you do not want to remove or unduly abrade the good plating underneath. You do want to leave a bright and burnished surface when you are done.
There is one other spot-cleaning tool for brass that should be mentioned here. These are the pencil shaped brushes known as 'fiberglass erasers'. These are marketed by various model manufacturers and can be found in some office supply stores. They come in the form of a thin (1/8") shaft of fiberglass strands in a pencil-like holder to feed it out as needed. This tool is absolutely great for spot cleaning brass. It will remove corrosion and tarnish, and import a very clean surface for improved electrical conductivity (great for soldering preparation too). However, be forewarned, as the eraser (or brush, if you prefer) does its job, tiny little bits of the fiberglass strands break off. These have a tendency to reappear later, imbedded in your finger and will cause untold distress until removed. Removal is sort of a challenge as these fragments are virtually invisible except under strong light and eye magnification. You will know one is there, though, when you brush the finger against something and you get that small and brief, but severe stab of pain. I strongly urge eye protection when using this little devil; these bits of fiberglass are very light and can easily become airborne. I have been irritated enough by these, that I rarely use this tool anymore, unless absolutely nothing else will do the job. Just thought I'd mention this;....... your choice!
Mechanical/Drive Train Areas
We will address three areas here: Motors, gears/gearboxes and driver axles: There are two basic classes of motors; the older Open Frame style motors and all others (Can motors, Micro-motors etc.). All of the second type are fully enclosed and as such, generally are not prone to collect dirt. They also are designed to require no maintenance other than an occasional touch of lubricant. Indeed, many of these are constructed to inhibit disassembly, by tinkerers, as well as professionals.
This leaves us with the open frame type to consider. A good open frame motor, if well maintained, can produce very fine operation for a locomotive. The elements that require occasional attention are the commutator and brushes. The brushes are made of a carbon compound, and as such, they tend to wear down with use (like a pencil). In doing so, the worn-off carbon tends to accumulate on the commutator in the form of black deposits, and over time, in the segment slots of the commutator. If these slots fill up to the surface, you no longer have a commutator, you just have an electrically conductive cylinder, and the motor will behave poorly, draw higher than normal amperage, or not run at all.
Anyway, periodic cleaning of the commutator is very worthwhile. A track cleaner or electric contact cleaner does a good job. So does TV Tuner cleaner, which leaves a small amount of electrically conductive lubricant. When you have applied the cleaner, a simple and very effective tool to remove the gunk and burnish the surface is a common stick of Balsa wood, about 1/8th inch square. This is porous enough to soak up the gunk and solid enough to remove all but the most stubborn deposits. As the end gets dirty, just slice off to a new surface; a 45 degree angle works well. Another relatively recent product that works well is 'CONDUCTA-LUBE' Cleaner, by Atlas. This is a plastic compatible cleaner / lubricant made specifically for small motor commutators and brushes. To clean the carbon / gunk buildup in the commutator slots, a sharpened toothpick is effective. After you have a clean and dry commutator, polish with 400, then 500 and 600 wet/dry papers, then finish with a wood pencil eraser or 'Pink Pearl' eraser. Be sure to blow or brush off all residue.
Gearboxes, driver axles, and bearings can also require periodic attention. Older petroleum based lubricants can harden over time and actually impede rotation instead of promoting it. Even if not hardened, the lubricants in these areas will collect dirt over time, and will start to act as cutting pastes instead of lubricants. Any mild liquid cleaner will do a good job. An old toothbrush and Q-Tips will aid in the scrubbing process. If you use Q-tips, be aware that these tend to leave strands of cotton on surfaces. It helps to clip about 1/8th inch off the end of the cotton tip. Do not use Q-tips to clean motors; you will leave troublesome bits of cotton no matter how careful you are .
DO NOT use Crocus Cloth to clean brass or plated surfaces, especially motor commutators. The abrasive on this stuff contains very fine iron particles, and will contaminate such surfaces and really louse up the surface and conductivity of a commutator.
Lubricants:
Motors, even sealed 'can type' motors, require periodic lubrication. Most open frame motors have a felt pad at each end of the motor shaft. Oil this pad. You want the pad saturated with oil, but not dripping. This pad will provide adequate lubrication, under moderate use, for a long time, sometimes up to several years. On motors without the pads, a pinhead drop or two of oil at each motor bearing is adequate. The same applies to gearbox bearings and axles. A little oil goes a LONG way. Too much oil spreads and contaminates other surfaces (electrical contact surfaces - bad news), and attracts dirt as well. Too little is almost better than too much, when it comes to model locomotive lubrication. If axles, especially driver axles, are dirty where they rotate in the journals, clean the dirt off before re-lubrication. Otherwise, you are just adding new oil to dirty oil. Driver axles and their journals are under the most load of any locomotive / tender axle. Cleanliness and proper lubrication here will keep driver rotation free and avoid sloppy rotational clearances.
Well, what do you use here? I have had good fortune with Labelle's lubricants over the years.
For motor and gearbox bearings, drivers and all axles, it is hard to beat Labelle Number 108. This is a very light plastic compatible oil. For larger motors in O scales, Labelle 107 may be indicated. For gears, Labelle 102 is excellent. It is a true gear oil which is also plastic compatible. Labelle 106, a Teflon bearing gear grease (also plastic compatible) is a viable alternative for gears. It is only necessary to have a film of gear lube on each gear tooth; it is not necessary to have the gears swimming in it.
Equally good lubricants are marketed under the 'HOB-E-LUBE' banner. They have also recently introduced a new line called 'HOB-E-LUBE PREMIUM' lubricants. Atlas also makes a quality motor bearing and axle lubricant, as well as their previously mentioned 'CONDUCTA-LUBE'. PBL also markets an oil especially formulated for brass models, which contains Teflon, and is called 'Trick Oil'. Most model lubricants made today are synthetics, and as such, do not readily suffer the eventual gumming and hardening that petroleum based lubricants did. However, any lubricant, no matter how modern, can be contaminated by dirt. Long life for rotating surfaces is achieved when such surfaces are both lubricated AND clean.
Most of the lubricant lines mentioned above have several grades of oil, making them suitable for all scales, from N scale through O scale. I suspect that the heavier oils in those lines would be suitable also for G scale brass models.
A Word of Explanation:
In the previous Tips, on diagnosing shorts, I stated that it was a convention for the right rail to be positive ( + ) and the left rail to be negative ( - ). In truth, the assignment of (+) or (-) polarities is defined relative to the direction of the locomotive. If the locomotive is going forward, the right rail is defined to have (+) polarity. The polarity that the motor terminals actually get depends on the gearing of the drive train (e.g. idler gearbox vs. non-idler gearbox). I chose the convention described in the 'Tips' as what I conceive to be the easiest way to describe and think about the polarity differences between the locomotive and tender for the purpose of diagnosing shorts. Furthermore, when discussing the frame of the locomotive as 'ground' for the motor, it is more natural to associate the term 'ground' with the (-) polarity, especially if you have ever dealt with automotive batteries. The discussion on diagnosing shorts does not suffer in the least from this transgression, but if I have confused anyone or offended knowledgeable purists, I humbly apologize.
Summary
The following is a list of cleaners and cleaning tools, which should be suitable for most cleaning tasks that you will encounter. Within each category, the items are listed in approximate order of increasing aggressiveness.
LIQUIDS:
BRUSHES:
PAPERS:
OTHER:
MOTOR/AXLE/GEARBOX BEARINGS:
* Not plastic compatible or not specified as plastic compatible.
GEARS:
MOTOR COMMUTATORS:
* Not plastic compatible or not specified as plastic compatible.
DRY LUBRICANTS FOR AXLES:
* Not plastic compatible or not specified as plastic compatible.