Here is how I thought up how to make an archtop woodie from a block rim. I would be using a router on a compass guide with a 1/4" straight bit. The steps are in the photos. Let me know what ya'll think!
Gosh, back when I was in high school, about 55 years ago, we would “rout” wood. “Route” (with the “e”) was something else entirely. I suppose, if you choose the highway directions for a truckload of lumber, you could “route” wood”.
If you want an archtop woodie why not simply angle the top of the rim? I don't see where you gain anything from removing material between the inside and outside edges, but I'm basically lazy.
Not to overly-complicate things, but your method of routing the deep groove in the top with a straight cut bit is going to be very prone to blowing out a portion of the inner or outer wall of the cut from the trapped bit. (Yes, I have personal experience with doing it!)
Hunter, I would not assume anything, and radiussing and beveling might not be the B's knees .
I mentioned on the hangout that Lange's double flatbar archtop was a feaux archtop, and one of my elders corrected me to say wisely that no, it IS an archtop. So archtop woodies are just that, I suggest you don't just make it LOOK like the metal tone rings. It already will act like and is an archtop without using a radius and a bevel.
Again, another thread got mashed because I mentioned an ancient technique of using a Hyperbolic curve for the head to break over instead of just one radius, it has a changing radius so it is gentler on the head. It's about 5,000 years old , so you don't have to listen if you don't want to. It's been used in banjos before. Standardization and regimentation would not necessarily be representative of ALL the banjo community. Archtops reduce the chamber diameter to try to get more projection than a flattop, that's it. It was a vaudeville thang. The new chamber created by the sloping head might need "trumpet" holes on a woodie to prevent severe muffling.
I've built a few of these, but I found the introduction of my little contribution of Fresnel ledges creating 3 different chambers inside the rim, greatly increased the production of quality sound. However, I don't use the horizontal grain orientation that you and so many others propose.
Mine gets used every week in public, I just listen to my customer's specs and results.
Do not ask Hunter what he wants to do this for, he has the right to move about.
A while back I was contemplating making a woodie archtop, and I made a drawing to see what it would look like.
My feeling about it was that a bronze archtop has some pretty sharp edges that might not be that good with wood - chipping etc.
Here's the drawing, shown next to a conventional archtop in the event it could be useful to you. Of course, you are doing it all in one piece.
So maybe I should use a core box bit for the channel? Then use the roundover bit for the rest?
That sounds like a good idea. I think with a wooden part, you want to eliminate sharp inside and outside corners, where it could break, and it needs to have a thicker section than a metal one - metal is much stronger and looking at the drawing, the head is going to pull the edge of the tone ring inward where it first comes in contact, and having a radius in there would make it stronger.