The first thing you have to do is to get a base router that has a single rod installed at the base. Place it where you want it and hold it down with bar clamps. Drill a hole through the end of the wooden fence rod. A single nail will serve well as a pivot point.
No matter which one of these jobs you want to do, always set the radius between the closest cutting edge and the trammel point. Some projects are easier so you can find the trammel point just by pressing the point of the router to the surface you’re working on.
Also, feed the wood against the cutter’s rotation to decrease the forces along the trammel rod axis. If you pull it away from the center, you can quickly lose the center point, and you’ll have start all over again. Sometimes it can be hard to figure out what direction to cut to, so remember this – always cut anti-clockwise on the outside and the opposite when working on the inside.
One of the things you’ll have to keep in mind is the center hole. If the trammel point makes the hole bigger, you’ll lose the accuracy, and you won’t have a perfectly matching cut when you make a full circle. If you want to make several identical cuts on the same center point, you should probably replace it with a small rod that fits into the hole of the pad. That will help you create identical circle cuts, but still, you should be careful because other things can go wrong.
For example, the cable often tends to get in the way when you’re trying to make circular cuts, so try to attach it to the ceiling or above the bench so that it won’t get in the way.
Maintaining a smooth and steady movement with the router needs some practice, but you can do things to make the process quicker. Swing the router as you cut as far as you possibly can. When your arms cross, just switch hands and continue cutting the circle. Don’t stop cutting while changing hands, to make sure you get a perfect circle in the end. If you pause while you switch hands, the router will create a burn mark on your wood due to friction.
The smallest possible radius of a circle cut is the same size of the base of your router, which is often too big for smaller cuts. Trammels with guide rod holes can help you make cuts as small as 25mm in diameter, but that’s going to be tricky because the pivot point is now mounted underneath the router.
If you don’t want to do everything by hand, buying a template with predrilled holes of various diameters is a great idea. You can use a guidebush or a straight cutter and combine it with the pre drilled-holes and a template profile cutter; you can make holes of almost any size. Of course, you’ll need some time to master the process, but practice makes perfect, right?
Cutting circles and curves into wood is a tough task without the right tools. Some craftsmen can make perfect cuts every time, but it took them decades of practice to get to that level. If you don’t have that much time to practice, all you need is a base router table, a trammel rod, and you’ll make some sweet circular cuts in no time at all. Good luck!