Tools for working with composites range from repurposed kitchen and craft utensils to tools designed specifically for a task in the composites industry. It’s best to have the professional tool, but sometimes a butter knife will do.
Cutting Glass Cloth
A good, sharp pair of scissors is a must, but learning how to keep them sharp is also important. A cheap pair of scissors in a vise and a good file will help you practice keeping your good scissors sharp. Keeping the tip sharp is useful in situations where a little snip is needed or in a tight place where just the tip will reach the glass. A rotary cutter used in the fabric world is a great, fast way to cut straight and complex parts without distorting the glass shape. A self-healing mat is needed for the roller cutter and is available in different sizes.
Cutting and Grinding Cured Glass
Mini diamond wheels available online or at Harbor Freight help shape and trim composite parts. They allow a piece to be cut off rather than grinding or sanding it away. The diamond wheel can also be placed in a foam panel, parallel to the skins, and moved up and down removing about a quarter-inch of the core from the edge so it can be backfilled for a stronger edge. Small burr bits also help in shaping and plunge cutting into a composite part. Many shapes are available and are made by a few companies. The bits shown are all Kutzall bits with a 1/8-inch shank for use in a Dremel rotary tool. Perma-Grit makes a large variety of shapes. Fine, coarse, and extreme are available with the coarse being the most useful. Perma-Grit also makes a set of hand files that have a variety of shapes for multiple uses. These burrs and files will last many, many years. Some of the burr bits shown are well over 10 years old as are some of the Perma-Grit hand files.
Next on the list would be a 90° die grinder with a 3-inch sanding disc with 80 and 36/40 grits. This tool can be used to get after a large glass grinding job or, if used carefully, a delicate removal of gelcoat, primer/paint, or even roughing in a glass bevel for lamination. While on the topic of larger tools, a oscillating-tool such as the Fein tool can make short order of a glass laminate with a coarse heavier particulate rather than a fine dust from sanding or cutting with a rotary tool. It has come in handy but is only another weapon if needed in bigger jobs.
Mixing Resin
When mixing catalyzed resins using methyl ethyl ketone peroxide (MEKP), a digital scale is a must. There is a drops-per-resin quantity technique that can be used, but a syringe is desirable and a lot easier. In general, the specific gravity of a gram of resin and a gram of MEKP is very close. A gram of catalyst is approximately equal to a cc or ml on a syringe. If mixing 100 grams of resin at 1%, a cc/ml (one gram) of MEKP will be needed; 2 cc would be 2% in 100 grams. The math is quick and easy this way. The syringe is much easier than counting drops per resin quantity. A 3 cc or 5 cc syringe will give the ability to easily dose in 0.2 cc increments, so it’s convenient for smaller 20- or 40-gram batches of resin. Not all syringes are created equal in construction or cost. Cheap plastic, black rubber-tipped plungers are common. The black rubber will ultimately degrade—sometimes contaminating the catalyst—and you’ll have to throw away that syringe. The plastic tip plunger type tends to “grab” while pulling or pushing, leading to an extra bit of effort to dispense the MEKP into the resin, causing potential splashing of the corrosive and dangerous MEKP. If you really want to spoil yourself, buy some glass epidural syringes. They are about $15 for two. The matched ground plunger floats effortlessly and can be used one-handed. They will virtually last forever as long as they are not dropped.
Epoxy is either mixed by volume or weight. If mixed by weight, a digital scale will be needed as with the catalyzed resins. When mixing epoxy by volume, graduated mixing cups or metered pumps are typically used for volumetric measuring. Ratios will vary from manufacturer to manufacturer and have nothing to do with the rate of cure.
Spreading Resin
When glassing, a smaller 4-inch squeegee/spreader will help apply the resin to the glass or putty to a glass laminate. The squeegee is also helpful when removing air bubbles but suffers when chasing the smaller air bubbles. A larger, rubber squeegee is good for large flatter areas. Smaller air bubbles can be tackled with a quarter-inch or 3/8-inch glass roller. It does great on larger, flatter layups and will move the small air bubbles to an edge.
What are your favorite composite tools?
What a world of knowledge–thanks Zach!
What is the cleaning process for the metal roller ?
I use a little acetone in a mixing cup. The roller is loose on the handle so a little agitation helps clean the resin off. At some point the resin will gunk up the inside of the roller and it will stop moving. That is when you breakout the propane torch and wire brush and basically burn the cured resin off the roller and clean the groves with the brush….. Watch the fumes! The heat will also burn most of the resin out of the inside of the roller. The roller is also held on to the roller shaft with a screw in the end. Remove this screw and the roller will slide off and the shaft can be final cleaned with scotchbrite. Sounds like a lot of work for a cheap roller, but it really does go fast.
Electric scissors are a favorite of mine.
Got a cheap set (with an extra blade head) online, they work just fine.
My cutting table doubles as the fold-down door over my fabric roll cupboard. The cutting surface is just inexpensive thin hardboard screwed over a wood panel. It takes a little damage from the rotary cutter, but not enough to be an issue so far. If it does eventually get too rough, I can readily unscrew the surface and replace it.
I also replaced the lightbulb heater for my epoxy cabinet with a little 100w electric heater connected to a temperature sensor to cycle it on and off as needed – keeps the epoxy reliably at whatever temperature I choose!
I had electric scissors at one point but for me they were hard to get into build locations where glass had to be trimmed in place. I found old habits brought me back to standard scissors.The electric did great on the pre-trimming of laminates.I should revisit the electric shears!
The cutting mat gets rough as well which hinders clean cuts of the glass fibers in places. I lightly sand the mat with 220 grit and it solves the cutting. Great idea on the ceramic heater with adjustable sensor.