By which I mean, it's been dismantled eight times, neck reset three times, three cones, six bridges, three nuts, three sets of strings and I've also made it one inch less deep.
I've now installed a Continental cone & a biscuit with the saddle moved a few mil to improve the intonation. I made the well less deep, which raises the biscuit / lowers the saddle which looks loads better & gives more space between the strings and coverplate. I also fitted a brass plate on the back to stiffen the neck joint.
The remaining issue is a slight twist in the fretboard around the 12th fret which I've overcome by doing away with the frets past the 12th to stop it fretting out. A job for another day when I've learnt how to cuts slots for frets.
The back is more or less unfinished in case I needed to get inside the darn thing again. I tried several materials for the back and settled on good quality 5mm plywood, which sounded the best and stayed in exactly the same shape as cut. I'll conceal the screws and lacquer it when it's had a while to settle.
What a labour of love, beautyfull to see. Made around a guitar cone isn'it?
I've noticed that China made resonators mandolins have a less deep soundwell than vintage Nationals or modern NRP's, because they built them around the primitive "Johnson" cone, (without spirals and with a flat top, that can acomodate the two types of biscuits ( mando or guitar), those cones are useless... I ended up to fit a guitar cone and reshape the large biscuit to fit the smaller hole coverplate...tricky but works pretty well. Seems like height short strings could make a good job on a guitar cone.
I've seen someone playing on a "Republic" with a NRP cone...and no coverplate...I can imagine that risky choice was made because the new cone is too high for the coverplate... Asian made resonator mandolins seem to have the same lack of deepness for the soundwell (Nowadays their cones seems to have a correct small bowl, and spirals, but are they still made with the heigh of a guitar cone?... so with an "hybrid" cone made with a different angle...if anyone knows?...).
(I Dream to get able to build my own one like you, some of these days!)
I started with the recessed coverplate, which gives more room for picking. On nearly all Resonator Mandolins the strings are too close to the coverplate & there's a constant clicking as you hit the top.
I tried several cones but a new guitar sized Continental sounded best.The most important factor is the string angle over the bridge which came out at 10 degrees. (i.e. 170 degrees)
Everything is much more tricky on a short scale Instrument, especially intonation.
It's stayed in tune for 24 hours which is good news.
It's a very clever idea to use that type of coverplate, somekind of "dobro" shape, ...sometimes I even put some felt on the coverplate to get cleaner recordings.
(Those cheap modern mandolins have a much more higher hand-rest; so it's fun to see how they try to find more room, by getting an insane height and neck-angle; obviously not the best way to get a nice sound...my friend can't play more than ten minutes without getting an headache...too much strident, but powerfull for sure...the difference between noise and music can be very thin sometimes...).
I'm still fighting with intonation too, because my scale is wrong (maybe because someone had removed too much material at the heel, so my twelve fret is a bit on the body, so I simply put my saddle out of center on the biscuit...It's the third Johnson I've got, everyone with a completely different neck, and each with different troubles to solve, but this one seems to work pretty well now...).
Can you please tell me wich weight implies your type of building?
I've heard that the guys from NRP had made few attemps to built a hollow body like old Nationals, but they wasen't satisfied with the tone of it, that's why they get something more solid, I suppose that's why you choose this approach?
It seems very efficient. But I never seen or played on this new type of instruments.
Yours looks truely like she was made in the thirties !
I went for solid sides as I didn't have the skill to bend the sides from solid wood or ply. I had a piece of old Mahogany I'd found a few years ago, maybe 25mm thick. I originally used three layers for the sides. When I stripped it down the first time, I took out a layer as it was really heavy.
The front is 10mm veneered ply and the back was the same, but I found 5mm to be more resonant and lighter so I replaced it with that. I've also had two Johnsons in the past which were nearly very good, but I didn't have the confidence at the time to reset the necks.
I made a biscuit from 5mm ply with an offset saddle to adjust the intonation. The ply works very well for the biscuit as it's light and stiff. The weight of M1 is now just over 2KG which is comfortable.