This is my first post but couldn’t resist chiming in on this one. Dremels are horrible for cutting composites. I went through countless abrasive disks cutting FRP. The reinforced disks aren’t much better than the standard. They normally break off at the mounting hole because there isn’t enough surface area with the way the disk is mounted. I also went through a few dremel motors as well. As somebody stated earlier, the electric motor fills up with dust and failure happens fairly early in it’s life.
More recently I’ve been using an air saw. Some would call it an air hack saw. Many blades that work well can be found easily enough and it’s not difficult to cut down larger blades intended for other cutting tools for use in this saw. I’ve found the air saw to cut through most composites like butter.
I cut close to my final trim line and then use an air sander to finish the edges.
I’ve also used a bandsaw to rough trim parts that would fit. Inflatable drum sanders work nicely as well. They make quick work of getting parts to final dimension. I’ve also used a large table belt/disk sander with success in the past. One of the tricks to making the large stationary electric tools last is having a LARGE vacuum system running to collect the majority of the dust while the tool is in use. The shop where I used these large electric tools was a prostetics shop. Each tool had custom vacuum intake to collect dust connected to a 6" hose. There was a butterfly to close the intake at each station not in use. The vac system was large but probably not difficult to purchase or build something similar. I know the electric tools in this shop had been in use for years and are still in use today. A nice additional perk to the vacuum system was VERY LITTLE itch from cutting and fine tuning the edges of parts. Back when I got the chance to make a few parts in this shop I still itched when trimming FRP.
For a few parts that I make repeatedly I’ve been thinking about making a jig with metal bearing guides for a router bit to trim these parts. Then using the router bit in a air grinder or similar. Should make quick work of trimming parts but would be a lot of effort for low number parts. I thought it might be easier to use hardened steel and let the bit ride directly on the guide. I should be able to use the original plugs to build the jig.