Mechanics Rules

The mechanics rules are based in the nature of things. They are not rules to follow but rules to know. Working with these rules in mind should increase your effectiveness, decrease your frustration, make your projects look better when done, and make your tools last longer. Although these are general rules I have placed the emphasis on plumbing, no surprise there.

Mechanics rules.

Over the decades since I started turning wrenches and manipulating materials I have come to understand certain things about work, tools and materials. I earnestly try to pass this understanding on to those that I apprentice, just as many of them were taught to me by my journeyman. An apprentice may have more than one journeyman to train under, as I did, yet one may loom larger then the rest combined so when you speak of that person you say “my journeyman”. In my case he was the person who actively saw to it that I got my ticket. I am a journeyman today because of him. In a sense when I say don't put teeth on brass it is not entirely me speaking.

Mechanic's Rules,

What can you add to this list? What use of tools or rule of materials do you think is missing?


Never use a toothed tool on brass. Use a flat jaw wrench, a strap wrench, an internal wrench, a nylon pliers, a spud wrench, a pair of locked nuts, but no teeth!

The first thing I do on any job is assess the need so that I may chart a proper course of action. As part of that assessment I consider the condition of the materials I am to work with. When I see pipe wrench and pliers scars on parts that should never have those marks no matter how many times they are worked on I look for the things that usually go with those scars, over and under tightened parts, damaged threads, parts miss-assembled, missing parts, once round parts forced oval by miss-application of force etc. Those wrench marks tell me I am following an untrained and or careless worker. One more thing to consider before you work on those softer than steel parts is that those marks that standard pliers leave are not just gouges, but sharp high points as well that cut and break off in the callouses of your hands.

Nonferrous work

Brass is not steel. A two sided wrench will change the shape of a brass nut, forcing it to oval. If it doesn't turn at first move your wrench to a different pair of sides. Keep changing, each change does a little work. As you work follow the next rule.

Loosen to loosen, then tighten to loosen, then loosen to loosen, etc. It is patience that moves brass, not strength. Augment your efforts when necessary with blows from a nylon hammer, the smaller the part the more modest the blow. Strike with the hammer around the circumference of the part.

Brass is "grippy" on brass. Two brass parts require a lubricant to tighten on to each other. That squeal you hear is the sound of a high speed chatter between the surfaces. It warns you of a false torque on your parts.

The most common mistakes I see where do it your selfers have gone before me are the mishandling of materials, and wrong assembly of parts. I understand the problem of new materials because I worked on all manner of devices, power tools, cars, trucks, bikes, cycles, even bowling pin-spotters, for years before I started working on pluming. Almost everything the common mechanic works on is made of steel. When that person starts working on nonferrous plumbing the shift in style approach and torque is hard to make. The best thing to do when you work with unfamiliar materials is to be observant, go slow, get advice, and treat it as the learning opportunity it is.

As for order of assembly, once again stay observant. If you take something apart study it as you go, take photos. If you work on an assembly read the instructions.



I am big on reading instructions. When I am working with a product that is new to me, or researching for a prospective purchase I review the instructions. In the paperwork I find details about the orientation and sequence of parts to be assembled. The tolerance finishes and parts may have for putty, thread seal, glue, pressure and heat. I get the “do”s, the “don't”s, and the troubleshooters guide.

I respect the engineers who create the materials I handle, and if I can't I try not to handle their materials again. The end result is that familiarity with the manufacturer's data increases my success rate, and reduces my failure rate. Needing to go fast is no argument against the instructions because it takes less time to do it right than it does to do it twice.

Please do read the instructions. If they disagree with me, follow them. If they don't make sense read them again, or get help. I make great use of tech. support on the manufacturers dime, so I dial 1-800 without blushing a bit. I understand that some folks don't like to look like they don't know what they are doing, but they run the risk of proving it.

Rules of tools and materials


A nylon hammer will jar, but not mar. Use a nylon hammer to loosen parts that are frozen in place. Plumbing fittings that have leaked may have stopped leaking because the seeping water filled the threads with lime. Lime is stone, jarring the joint may help reduce it to dust

A lead hammer will deliver a powerful impact to steel but will be marred instead of leaving a mar. A lead hammer will not throw a spark.

A wooden hammer will shape moderately malleable metals.

A leather hammer will shape very malleable metals.

A brass hammer will not throw a spark.

Materials and "work"

Cold shrinks materials.

Heat expands materials.

Most materials become more brittle when cold.

Work hardens metals. If you keep bending it, it will break.

Vibration is work.

Expansion and contraction is work.

Wrench work

Two wrenches set 180 degrees apart will turn an object with no lateral torque. A single wrench tends to push parts sideways. Two wrenches set opposed will apply force to a part on its center axis.

Two nuts form a lock. To turn a threaded shaft run two nuts onto it, tighten them toward each other, and turn the shaft by wrenching onto the following nut. When done loosen the two nuts away from each other and remove them.

Think about where your hand will go if the wrench you are pulling or pushing slips form its place.

File work

Back stroking a file breaks the cutting teeth. Lift the file on the return stroke.

Watch the result of each stroke by angling the work to see the light reflected off of the surface of the piece being worked on. In this way you can know when your stroke is off angle. Doing this will train your hand, train your eye, and bring you closer to mastership.   

If the file face accumulates metal crumbs during work wipe it on a terrycloth rag to keep it clear of the debris. This will keep it cutting instead of sliding on the piece.

Get a file card, (a short bristle wire brush made for cleaning the cutting teeth of files), and use it to clean your files after each use.

Unprotected carbon steel cannot be left wet. Rusty files are worthless. Keep them dry!

Oil grease and petroleum based plastic

A thinner oil always dissolves a thicker oil. The oil of your hands is thicker than the oil in some hand cleaners. Continued use will cause split callouses.

Some plastics are thick oil. Toilet wax is non-petroleum, it will not harm ABS. Plumbers putty is petroleum based, it will harm ABS.

The less is more rule of materials

The weaker the material the more of it will be needed, hence a cast iron sink is thinner than a china sink, which is thinner than a marble sink. It is also why plastic threads are typically coarser than metal threads. A coarse thread has a steeper ramp than a fine thread, this is the reason plastic threads loosen more readily with movement, [work] than metal threads do.

In cast and machined materials less material is a sign of quality, indicating that the manufacturer has confidence in his production style. Those without confidence use more material to create strength or prevent leaks.

The OEM rule of rubber

When replacing parts made of rubber it is best to use parts made by the original manufacturer. There are at lease two reasons for this. The hardness of rubber, as measured on the durometer scale, greatly effects its performance in any specific application. Rubber is molded, or extruded. The original manufacturer has the most compelling motive for your continued success with his product. The parts you get from the original manufacturer will have the proper hardness and come from the best molds.

The best example of this is a Delta faucet seat, the difference in the expected life between Delta seats made by Delta and Delta seats made by "other" is notable.

General practices

Properly maintained tools make work faster and safer.

A clean shop makes work faster and safer.

Machines hate dirt. Dirt is abrasive to moving parts, wicks off lubricants, and holds moisture.

Measure twice cut once. Measure that $5,000.00 tub for drilling at the end of the day. Go home. Measure it for drilling again in the morning ignoring your earlier marks. If all is the same, drill it for the faucet.

Never break a rule you don't fully understand.

If you want to know why the pros. don't do it a certain way go ahead and do it that way, then you will understand.

If you hire a pro to do something tell her or him what you want done, not how to do it.

Practice courtesy, civility and respect.

If you cannot please someone, do not work for them.

Respect your own intuition.

Pay attention to the ideas and solutions you awaken with.

Make your work last longer.

Content contributed by,

Will of Kenmore WA.

Applying the general list and practices of these stated Mechanics Rules will also make what you work on function optimally for longer and last longer.

Thanks Will, well said.

Words Of Wisdom

Submitted by:

Luke Noderer,
of Kentucky

This one was given to me by grandfather, who was my first and best teacher.  Over the course of my life in the shop, in the field, and in general, I have found this one rule to be more applicable and more important than perhaps any other, even the "Golden" one.  Plan your work properly and thoroughly before proceeding, and you will eliminate re-work.


Don't pick up anything -especially anything heavy- until you know where you're going to set it down.

Thanks Luke, the point of this page is to pass on the things we learned along the long road to proficiency, and just as importantly,  to acknowledge and pass on the wisdom that was passed to us in our turn.  You truly get it. 

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