Before you begin, make sure you’re using appropriate safety gear! As you are trimming you will create carbon and resin dust. Prolonged exposure can cause irritation of the skin, eyes, nose and lungs. Suggested safety equipment includes:
The trimming process begins where the lay-up process ends. Depending on the resin system used for your part, you may need to wait anywhere from hours to days for your part to cure and be ready for trimming. If needed, use a silver sharpie to mark where you will be trimming. Make sure your part is securely clamped and that your work area is well lit. You will need to readjust the clamps as you work your way around the part.
Starting with your rotary cutter, work your way around the perimeter of the part. Aim to leave 0.25-0.5” of extra material, but always err on the side of caution. Rotary tools are prone to jump suddenly, so be mindful of what is in the path of your blade--one mistake here could destroy your part. It can be helpful to practice your technique on a scrap part first.
Switch to your rotary grinder. As before, caution is key so move slowly. You can always grind away more, but you can’t add material back. Use the grinder to incrementally remove material, adjusting your clamps as needed until your part is complete! You can leave your edges a little rough. Don’t worry about loose dry fibers on the edges either--fine detail is best ground down with hand tools for maximum control.
Don’t worry about loose dry fibers on the edges either--fine detail is best ground down with hand tools for maximum control.