I built this mandola a few years ago from a nice Cohiba box. Turned out well; the neck is bolted-on and it's held the tension of the full eight strings for several years.
I've started in improving it, however. I've removed the glued-on copper-wire frets and I'm going to install real frets.
I would like to experiment with thinning the top down. It's solid cedar, and about 7mm thick. I do have it cross-braced.
I'd like to take that down to about 4mm to see if the sound improves.
I don't have access to a surface planer... I considered just putting sheets of sandpaper on a glass surface and starting to sand, but that's going to be tedious.
Anyone suggest a more efficient method?
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Hi, as the tops are solid cedar, not ply, and about 2.5mm thick that is a very fragile area so I reinforce the top with a very thin venneer cross grain to the top.
Taff
Mark Werner > Taffy EvansAugust 21, 2017 at 6:38am
Remember, in this case I'm dealing with the tension of a full set of 8 strings on this instrument.
I'm erring on the side of sturdiness! This mandola is several years old, and it's shown no sign of the bolt-on neck loosening or of any collapse with the existing top, which is about 7mm thick.
Sound has always been at best, adequate.
I'm a bit afraid of pushing the boundaries on this one, so I plan to reduce the top to a total of around 3-4mm, and just thin and taper the existing bracing.
Easy enough to disassemble at some point if I want further experimentation.
If you recall I suggested removing those existing braces and replacing them after thinning the whole top. You mentioned that they are glued with a strong glue, but it is easy to remove them. I would chisel or plane down close to the glue line, then route the glue off with the raised area of timber down to your desired top thickness.
To help with the replacement of the braces maybe a bit of background will help.
Cross braces in an instrument are normally fitted as structural support, and carved down so as to enhance top movement but not lose their supporting strength. In order to support the downward pressure on the top the cross braces should go all the way to the sides, and are glued to them. In order to give the top the ability to vibrate/flex the braces are thinned strategically at their the ends.
An important part of cross braces is the joint where the two arms cross, this has to be tight.
I have shown two of a few different styles of bracing I have used, the small top area means less braces are needed and they can be light. Both these styles produced great sounding instruments. I have since gone lighter on both styles.
The bracing subject is far more involved than can be covered here, and involves many other factors that must be considered.
Mark I would suggest, if I may, that you could do a great experiment by tapping the top close to your ear, hanging between thumb and finger, I would expect it to sound dead with not much ring to it. Redo the bracing as mentioned and as you carve them tap and listen, that response will change, should come livelier and more musical. Sorry to ramble on.
Hi, did you get a more responsive top from this exercise as you wanted? Just one comment I would make. I did not realise you would be removing wood from the inside of the top leaving bracing in place, my comments were relating to thinning the whole top from the outside or inside surface, but you would have lost the logo.
My comment/advice is, for those who choose this method, is to think about removing the bracing and thinning the whole top and then replacing with same size or modified bracing that would further enhance the response of the top. I admire your dedication to achieving better sound, but that little extra work removing bracing may provide an even better outcome. Well done anyway.
Cheers Taff
Mark Werner > Taffy EvansAugust 17, 2017 at 7:26pm
We'll see how it turns out. I'm waiting for the new fret material now.
I did want to leave the top intact, both for the looks and to leave the action unaffected. If I cut away the outside, I'd have had to construct a new bridge.
Also, those braces were glued on with Titebond III, a permanent glue. I didn't want to risk damaging the top.
I like that jig! Please provide materials and dimensions.
Also, about those braces. Take a lesson from commercial git bracing. Thin those down from the middle toward the ends with a plane or sand paper, and also, give them a more triangular cross section: thicker at the bottom where they are glued, and thinner "upward" as in the pic - some sand paper, a sanding block, and elbow grease will remove the material fairly quickly. You'll get the same bracing, but the top will be even more responsive, so the git will be just that much fractionally lighter.
Mark Werner > Ron "Oily" SpragueAugust 20, 2017 at 12:44pm
Good advice. I was considering "scalloping" the braces with my Dremel, but an overall taper might be better.
Right now, I'm doing the frets, when I get those in I'll likely finish up the top and string it up.
Replies
Taff.
Taff
I'm erring on the side of sturdiness! This mandola is several years old, and it's shown no sign of the bolt-on neck loosening or of any collapse with the existing top, which is about 7mm thick.
Sound has always been at best, adequate.
I'm a bit afraid of pushing the boundaries on this one, so I plan to reduce the top to a total of around 3-4mm, and just thin and taper the existing bracing.
Easy enough to disassemble at some point if I want further experimentation.
If you recall I suggested removing those existing braces and replacing them after thinning the whole top. You mentioned that they are glued with a strong glue, but it is easy to remove them. I would chisel or plane down close to the glue line, then route the glue off with the raised area of timber down to your desired top thickness.
To help with the replacement of the braces maybe a bit of background will help.
Cross braces in an instrument are normally fitted as structural support, and carved down so as to enhance top movement but not lose their supporting strength. In order to support the downward pressure on the top the cross braces should go all the way to the sides, and are glued to them. In order to give the top the ability to vibrate/flex the braces are thinned strategically at their the ends.
An important part of cross braces is the joint where the two arms cross, this has to be tight.
I have shown two of a few different styles of bracing I have used, the small top area means less braces are needed and they can be light. Both these styles produced great sounding instruments. I have since gone lighter on both styles.
The bracing subject is far more involved than can be covered here, and involves many other factors that must be considered.
Mark I would suggest, if I may, that you could do a great experiment by tapping the top close to your ear, hanging between thumb and finger, I would expect it to sound dead with not much ring to it. Redo the bracing as mentioned and as you carve them tap and listen, that response will change, should come livelier and more musical. Sorry to ramble on.
Cheers Taff
Hi Taffy,
In both pictures you added a layer of material around the sound holes, can you enlighten us as to the reason? Cosmetic, structural or ? Thanks
Hi, did you get a more responsive top from this exercise as you wanted? Just one comment I would make. I did not realise you would be removing wood from the inside of the top leaving bracing in place, my comments were relating to thinning the whole top from the outside or inside surface, but you would have lost the logo.
My comment/advice is, for those who choose this method, is to think about removing the bracing and thinning the whole top and then replacing with same size or modified bracing that would further enhance the response of the top. I admire your dedication to achieving better sound, but that little extra work removing bracing may provide an even better outcome. Well done anyway.
Cheers Taff
We'll see how it turns out. I'm waiting for the new fret material now.
I did want to leave the top intact, both for the looks and to leave the action unaffected. If I cut away the outside, I'd have had to construct a new bridge.
Also, those braces were glued on with Titebond III, a permanent glue. I didn't want to risk damaging the top.
Also, about those braces. Take a lesson from commercial git bracing. Thin those down from the middle toward the ends with a plane or sand paper, and also, give them a more triangular cross section: thicker at the bottom where they are glued, and thinner "upward" as in the pic - some sand paper, a sanding block, and elbow grease will remove the material fairly quickly. You'll get the same bracing, but the top will be even more responsive, so the git will be just that much fractionally lighter.
Right now, I'm doing the frets, when I get those in I'll likely finish up the top and string it up.
And finally the mostly-finished top:
What a mess... Should have used my shop vac as I was cutting....
Now to re-fret.
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