I'm working on a project for my telescope and need to cut a circle into a half-moon shape. For this, I really need precise router cuts instead of saw cuts. The problem I'm facing is that I can't find a 3 mm straight bit that can cut all the way through the 19 mm plywood I'm working with, as it only cuts 10 mm deep. My plan is to drill 3 mm holes around the circle, about four holes, run the router for 10 mm, then flip the plywood and run it again to cut the remaining 9 mm. I'm worried though; when I flip it to reattach the screw at the center, even a slight change could throw off my router path. Does anyone think this method will actually work?
3 Answers
You don't necessarily need to stick with a thin bit like that. There are router bits available that are long enough to cut through 19 mm plywood, just make sure to take multiple passes and go a little deeper with each one. If you’re not in the USA, you can still find metric bits, just search for something like "spiral upcut router bit". If you do decide to go with your hole-drilling method, just make sure that the center hole is drilled straight up and down—using a drill press would be ideal for that!
Why go with a really thin bit? You might want to just run your initial cut as you planned, chop off the excess with a saw, and then finish up from the other side using a bottom bearing bit. It’s a simpler approach and should lead to better results!
Just remember, sometimes adapting your method can save you a lot of hassle!
If you're trying to get a good fit between two circular pieces, why not just make two circles using a larger bit? One for the outer part and one for the inner cut. It's more effective! For precision, do one pass with the router at about 6 mm, then use a bandsaw or jigsaw to cut away the excess. I’d suggest using a drill bit instead of a screw as your center—much more stable!
Awesome tip! I love the idea of using a drill bit for a more accurate center—it sounds much better!
True, I didn’t want to leave a big gap between the bearing and the other wood piece. I figured a thinner cut might be cleaner, but I’ll definitely consider that option!