1878 Style Dobson Banjo Tone Ring Spinning Process

Dobson tone ring day!!
I spin a few different Dobson ring profiles, and this style is likely my favorite sounding.
This ring is made of thin 24 gauge brass, making it VERY unfriendly for metal spinning. This thinner material work-hardens very fast and requires frequent heat treating to soften the material and make it malleable again to continue spinning. In studying the original rings, I have encountered thickness variance from 24 gauge (.024") all the way up to 16 gauge (.064"). I unfortunately tend prefer the tone of the thinner material with the highest profile arch.... so that is the one I normally spin.
This very high arched profile seems to show up most often on the early 1878-1881 banjos, but it is also featured occasionally on the later models. The general Dobson ring profile varied quite a bit depending on both HC Dobson's supplier at the time, as well as the individual spinning the ring. This particular shape combines my favorite aspects of many different tone ring examples I have seen over the years.
On the final spinning step, I try to work-harden the "bell" of the ring, by aggressively shaping the final profile and somewhat burnishing the ring with the tool. This is a technique used in high end brass instrument manufacturing, and makes the horn of the trombone, trumpet, French horn. etc. much harder. The more rigid bell ultimately leads to more note clarity and longer sustain. I believe the softer arch and harder "bell" from the spinning/annealing schedule is one of the features that makes an antique Dobson tone ring "honk" in a way that is slightly different than the modern reproduction banjos.

[@fralin1966]

Truly amazing !

[@dpgetman]

Very cool, thanks for posting! I've seen your spun over rims (I see one on your drill press in the back in this video I think). I make those as well and I'd love to see your process on those.

[@VanMeterification]

Thanks! I'll make a video sometime in the future on making the spunover rims. I use antique hand cranked beading, wiring, and burring machines, but a modern bead roller with interchangeable dies can be used too. I just like using the old hand cranked machines.