Aeromodeling Workshop Safety

Originally by Donald W. Brooks for Model Aviation

I have two goals for these discussions; the first of which is to make you aware of safety hazards you may encounter while building, performing flight preparations and flying your model. Second, I hope to arm you mentally with tools to avoid the pitfalls that can lead to mistakes and getting someone hurt. I will try to keep these discussions straightforward.

Aeromodeling safety is a defensive effort. This defense recognizes the safety risk: a combination of the probability of an accident happening and the possible consequence of that accident.

Generally, the consequence of an accident may be on one of three levels.

1) A first-aid injury – a minor inconvenience
2) A significant injury that requires medical help, such as stitches, to repair a wound
3) A debilitating and possibly life-threatening injury

The higher the safety risk, the stronger the defense we have to muster. If the safety risk is low, we apply only one or two of the multiple levels of defense. If the risk factor is high, we employ all possible levels. The five levels of safety defense applied to aeromodeling are:

1) Attitude
2) Pre-checks
3) Backup
4) Isolation
5) Barriers

The first three levels of safety defense are used to prevent something from going wrong. The last two minimize the risk of a consequence for an occurrence that is beyond our control. We usually apply these defense levels cumulatively; that is, we ensure the right attitude before we apply the pre-checks.

The application of backup normally implies that we have already ensured the right attitude and have done the pre-checks. However, there are occasions when it is appropriate to proceed directly from attitude to pre-checks to barriers. I will point out such instances.

By barriers, I mean personal protective equipment, such as a dust mask, goggles, earplugs or a hard hat. When we cannot provide adequate safety protection by reducing the likelihood of a safety problem, we must rely on preventing the event or condition from reaching the person or property by using a barrier.

Isolation means physically separating people from a safety hazard, such as an out-of-control aircraft that is about to crash.

Workshop Safety

Whether you are building a FF Peanut Scale rubber-powered model, rigging an electric-powered park flyer, assembling an ARF wet-fueled model, constructing a sport trainer from a kit or scratch-building a World War II fighter, you will likely glue, solder, cover, saw, grind, cut, bend, sand, assemble, and/or paint during the process.

I will address the personal attitude you need to safely perform these activities, the use of pre-checks for tools we use and the application of barriers, as appropriate, to keep our fingers, toes and other vital body parts out of harm's way while working in the shop.

Even experienced modelers who should know better and have been told lessons-learned stories from past safety events still make serious errors and get themselves or others injured. Why? The answer often lies in the modeler's frame of mind prior to the accident.

Modelers are more likely to make mistakes if they are in the wrong frame of mind—if they have the wrong attitude. If we are feeling hurried, stressed out, tired, distracted or infected with the Commodore Syndrome (overconfidence), we increase the safety risk in what we are doing.

We need to recognize when we are in one of these high-risk states and adjust what we are doing to minimize the probability of an accident. We may need to slow down, take a break, refocus our concentration or take a less-tiring position for the shop task.

We model-airplane addicts do many simple things with sharp tools. We also use tools and materials involving significant amounts of energy. When there is a lot of energy available, in whatever form – mechanical, heat, chemical, electrical or potential energy from gravity – the safety risk is elevated.

Following are some high-risk attitudes you may experience.

• Hurried:

We use modern quick-setting adhesives that make the building process much faster than in the past and the final product lighter. The risk is caused by the release of chemical and heat energy as the glue sets. In addition, you could glue something that should not be glued.

Cyanoacrylate glue comes in various thicknesses: thin, medium and thick. The thinner it is, the faster it sets. The thin stuff sets in 5 to 10 seconds.

To attach balsa pieces using thin cyanoacrylate, we would normally pin waxed paper over plans on a building board (which could be the back of a 2 x 4-foot ceiling tile), and then cut, position and pin the balsa pieces in place. Then we would place a small drop of cyanoacrylate on the joints of the balsa.

A building board was made from a 2 x 4-foot piece of ceiling tile glued to a ¼-inch backing of plywood, with the smooth back side of the tile available for pinning.

Sometimes you may be tempted to hurry and hold the balsa pieces together with your fingers rather than pin them, such as when laminating balsa pieces or gluing fuselage sides at the tail post. You may think pinning takes too long.

Such hurrying places you at greater safety risk. The thin cyanoacrylate wicks through balsa easily and can reach your fingers. If you have only a couple minutes before an appointment and think you can quickly finish that gluing job by using your fingers to clamp the work, reschedule the modeling work for another time. You would look kind of funny going to that appointment with a fuselage glued to your fingers.

Sometimes a drop of glue will harden in the delivery spout of a cyanoacrylate glue bottle. Before using the cyanoacrylate, check to make sure that the delivery spout is unclogged. Otherwise, nothing happens when you squeeze the bottle to deliver a drop of glue.

To clear a clog in the spout of a cyanoacrylate glue bottle, it's better to carefully unscrew the cap to work on removing the clog. Be careful not to spill the glue from the open bottle if you use this technique.

When using cyanoacrylate glue, you need a backup – or a third level – of safety defense. Have a bottle of debonder readily available to unstick your fingers if the need arises. The debonder won't help your clothes if you spill glue on them; they will be ruined. The debonder should be available at any hobby shop that sells cyanoacrylate.

Cyanoacrylate glues are a mixed blessing for the model builder. Cyanoacrylate debonder can save the day if you glue your fingers together.

A final level of safety defense – a barrier – is necessary when using cyanoacrylate. Wear glasses or goggles for eye protection. Some of the glues get hot and fume as they set. If you drop the bottle, glue will splatter everywhere. If you get a drop of cyanoacrylate in your eye, your condition will require medical help.

Debonder may attack some of the new coatings on plastic lenses, so if you wear glasses you may want to use goggles to protect you and those expensive lenses.

• Stressed:

Have you ever had a problem with soldering? You may be stressed out because you can't get that wire lined up correctly with enough solder on the connector. And after three tries of holding the wire with pliers, the solder joint still isn't right.

You decide to hold the wire with your fingers for better control. However, 30 seconds later you are frantically looking for the burn ointment because you overheated your thumb and forefinger with a hot wire or a hot blob of solder.

There is a better solution. If you are getting frustrated, recognize it and don't push your luck. Don't reach for that soldering gun again; take a break. Find a path to relieve your frustration. Beat on a punching bag. Ride your bicycle around the block.

Come back to the shop work when you are not feeling frustrated. You will be much less likely to hurt yourself and much more likely to succeed.

By the way, there are better ways to hold pieces to be soldered, as shown in the soldering-station photograph below.

Proper tools for soldering can make the job much safer and easier. Notice the holder for the hot soldering iron and the clothespins that make it simple to hold small parts in proper alignment.

• Fatigued:

Today, we modelers have an easy solution for covering our models; there are many adhesive-backed, iron-on coverings. You can purchase a covering iron that is designed specifically for this job or you may use an empty steam iron with a temperature control to apply the covering.

Are there safety risks in covering a model? Yes, there are. After all, we have a good energy source: a hot iron. If you are tired, you are more likely to make errors during this task.

Your goal may be to finish the covering job before turning in for the night, but it could take longer than you thought. If you are getting tired, the longer you work, the more likely you are to slip and burn yourself. You are also more likely to lose your grip on that wing and punch a hole in the covering or in your hand while trimming the edges with a sharp hobby knife.

If you are tired or getting tired, get some rest and do the shop work later.

• Distracted:

Hobby saws are sharp, and they make cutting thick balsa or thin plywood much easier than using a hobby knife. I have several handsaws and a Dremel jigsaw I use regularly. For the handsaw work, you need a backing surface, such as a substantial wood block, that is sacrificial. You shouldn't care if you cut into it while cutting the work piece. For the jigsaw, you may need a piece of sacrificial wood to aid in pushing something through the saw.

As when using any sharp tools, your attention needs to be focused on the tool and the working piece. You cannot afford to be distracted. You should not be thinking about how to fly a Split S maneuver, how to solve problems at work, or how to get your son or daughter to take a stronger interest in his or her schoolwork.

Not paying full attention to the task at hand can be hazardous to your hand – particularly your fingers and thumb. If you get distracted, stop the cutting for a moment and refocus. Keep your mind and eyes on the work. Worry about those other concerns later.

Shown are common workshop tools. Having and using the proper device for a specific job is a safe practice. Learn to use all your tools in a safe manner.

• Commodore Syndrome:

This is a dangerous attitude. Unwarranted overconfidence in your ability to control the working situation without safety-barrier protection is inherently dangerous.

Let's say you are ready to work and can't find your safety glasses. What do you do? You may be tempted to say to yourself, "If I'm careful and don't stress the wheel by bending it, it won't shatter. I can do this."

I implore you to learn to identify this unjustified confidence for the danger it is. Recognize this safety risk. Use the barrier safety defense with a pair of goggles, and you will go a long way toward making your model-building experience more enjoyable and free of injury.

Ensuring the right attitude in preparing for shop work is the first level of safety you need to achieve. Then, don't sit on your laurels. You need a second level of safety – a pre-check of your tools – before beginning your work.

If the device is electrical, such as the soldering gun or Dremel hand grinder, make sure the tool heads are in good mechanical condition and tightly clamped, and that the power cord is not frayed, worn bare or nicked. If you are using a hand tool, look at the condition of the handle to ensure that it is tight and not going to come loose or crumble in your hand while you work.

If the tool is flawed, repair or discard it. Get rid of damaged tools that cannot be repaired.

In regards to attitude, I have discussed gluing, soldering, covering, sawing and grinding. Now, I'll cover the risks and levels of safety defense for cutting, wire bending, sanding, assembling and painting. With the right attitude and after having performed pre-checks of your tools, it's time to work. There are some valuable lessons learned that I can share to help you minimize your risk of receiving an injury.  

• Cutting:

Before I bought my self-healing cutting mats, I used cardboard, wood blocks or newspaper as a backing for balsa I was slicing. None of these was ideal.

The wood blocks and cardboard were dangerous because if I applied much pressure, the knife blade would follow the grain of the material. The knife could cut somewhere I did not intend. A new #11 blade in a hobby-knife handle can potentially cause an injury if you’re not careful.

Cutting against a backing of newspaper was a bit better, but I had to apply a great deal of pressure to compress the layers of newspaper before the cutting was effective. The extra pressure is not good.

Using these materials as a backing for your cuts raises your safety risk. You need a firm, non-grained, self-healing surface for cutting. Several sizes of these mats are shown in the photograph below.

Self-healing mats are available in a variety of sizes. They make cutting balsa parts trouble free. The mat's composition will not guide the blade, allowing you to make accurate and safe cuts.

• Bending:

This is a setup where gravity can hurt you. I needed to bend a 5/16-inch wire for a landing gear. This was too big a job for pliers. I needed to bring out the big artillery: a 5-pound vise.

Did I bolt the vise to the worktable? Nah! I was in a hurry. I clamped the wire securely in the vise, held pressure on the end of the wire, and formed the bend by hammering on the wire where it exited the vise.

Having completed the 90° bend in the wire, I pulled the vise to the edge of the table to free the wire. I was so eager to inspect the bend that when I loosened the jaws I didn't bother to push the vise back from the edge of the table. With no human control applied, it sought a more stable position by rolling off the edge of the worktable and onto my shoeless foot.

The arch of my right foot cushioned the vise's fall. It rolled off of my foot to the concrete floor, undamaged.

However, the almost immediate appearance of red on top of my white sock told me that my foot had suffered in this event. Fortunately, I didn't break any bones and just had to hobble around with a sore foot for several days.

Don't repeat my foolishness. If you are going to use a vise for any purpose, don't rush. Clamp or bolt it to a bench. In addition, when working in the shop, please provide the appropriate safety barrier for your feet; wear shoes.

• Sanding:

 There are two aspects of this simple chore that can be of concern for your safety, the first of which is that using folded sandpaper can be rough on your fingers.

I was in the midst of building a model once when I had to get fingerprinted for a security clearance. I had been doing a lot of sanding to lighten the model and get a smooth finish. I got the smooth finish on the wood all right, but my fingertips were smoothed as well.

The officer asked me if I had been trying to get rid of my fingerprints for some reason. I had to come back several weeks later to get the job done.

A good sanding board can save your fingers and provide a better tool. Most hobby shops have aluminum channel-backed sanding boards or you can make a serviceable one by gluing a piece of sandpaper to one side of a straight section of 2 x 4-inch wood.

Second, if you use a power sander, such as a sanding disk or drum on the Dremel tool, you should have barrier protection: goggles for your eyes and a dust (painter's) mask for your nose. When you need to do power sanding, you can minimize the dust you breathe and the particles that get into your home's ventilation system by running a vacuum cleaner with the inlet in the vicinity of the work surface.

• Assembling:

The screwdriver shown in the photograph below looks innocuous enough. How could it be dangerous? Look at the end of the inserted working head, with the Phillips-type end. It comes to a sharp point.

This multihead screwdriver is handy and safe when used correctly. Slips need to be prevented to protect your hand and arm.

Let's say you are holding a board to mount servos for your model. Using the Phillips screw head, you may apply 4 pounds of force to drive the screw into the wood. This force is concentrated at the small tip, which makes it effective in turning the screw.

4 pounds of force applied to an area measuring approximately 1/16-inch square translates to a pressure of roughly 1,000 pounds per square inch at the tip. If the tip of the driver slipped off the screw, you could easily nick or punch your thumb, finger, palm or arm.


If you are using spray paint to put the final touches on your model, please remember to use the appropriate barrier; wear a painter's mask. The hazard is breathing materials into your lungs that are not intended to be there.

I know it can be tempting to do small spray jobs in the shop, but that is not a good idea. Do it in the garage or some other well-ventilated place, or fix yourself up with a spray booth.

I hope this discussion has made you aware of some common workshop hazards, prepared you to adjust your attitude for safe work and armed you to put up a strong safety defense. Consider these thoughts, take them to heart and make them part of your shop work ethic. Apply the appropriate levels of safety defense in your shop work.

Good luck and good flying!