Repair/identification advice

[hobe12]

Hi All,

I recently purchased this cool looking mandolin from a junk shop. I assume its a low-end Chicago instrument from the 1920s/30s, but am not sure exactly. The top is starting to collapse a bit, but the tone and volume is great. I'd love everyone's advice on whether I should go about fixing it, and if so, any recommended procedures. One friend suggested inserting a dowel in the body below the bridge like some stand-up bases have. Pictures are below. Thanks for your help!

[Jim Garber]

Looks like a Supertone sold by Sears and prob made by Regal. I would not put a soundpost in -- that will affect the sound. I would check internal braces and see if any need gluing. You have some warpage on the treble side of the top. Once the braces are in tight then I might not worry too much about that warpage -- it may not be worth fixing and as long as it does not affect playability, then leave it alone. Others may have other suggestions.

[hobe12]

Thanks, Jim. So this will require I remove the back right?

[Jim Garber]

Probably. It is hard to get inside mandolins without doing that tho I suppose some folks can do it.

[bmac]

A nice looking instrument... I would love to have a two point oval hole!!

Your photos don't tell us much about condition....

How high are the strings above the first fret?

how high are the strings from the fretboard at roughly the 12th fret when tuned?

On the first five frets or so does there appear to be any wear on the frets (under the strings)?

regarding sinking bridge:
Your friend's advice would be disasterous. It ain't a violin... and the string tension is far greater.

Hopefully the bridge is not glued in place... You could replace it with a bridge with a longer base. or you could use a shim under the present bridge. But somehow you need to get the bridge at proper hight and then watch carefully for any further sinking.... You are at some advantage with an oval hole as you have pretty good access in there if need be. I would avoid removing the back for interior repairs if possible.

With a dental mirror and a small flashlight you may be able to see if the brace under under or near the bridge is holding firm.

Frets.com has lots of info on this kind of repair. Highly recommended reading before you undertake repairsof any kind.

[bmac]

Regardng removing the back.... I don't think you will have to.... That can be dicey and you should be able to do whatever work through the oval hole.... By the way I use an artists pallette knife with a very thin offset flexible blade... these are great for reaching into almst inaccessable spots and finding bad glue joints or re-glueing joints.

[RayMan7]

Thats a super cool mandolin, love the double point with oval hole. First thing to do would be remove the strings and see if the top moves, and check inside with a mirror to see if theres a lose brace. Its possible that the brace could be solid but just over time the top came in a bit, so you could just buy some ultra light strings, ones for bowlbacks would be good, and string it up and could have a nice player.

[Tavy]

Hard to see from the images how bad the sinkage is - Jim has it right, you need to find out if any of the braces are loose. De-string it, and use an inspection mirror to take a good look around inside (you'll need to get some light in there as well). Once you know where the braces are, press down firmly on the top directly above the braces. You should feel no movement. If you do there's an issue. Often this is a more reliable test than a visual inspection as it can be hard to see in there. If the braces are still glued in place then some sinkage may still happen over time and isn't necessarily a problem. Repairing the warp beside the soundhole is pretty easy too and will help stop the neck from pulling too far forward over time.

[fscotte]

Very cool. Would love to know whether the pick guard is real tortoise shell, and if the buttons are ivory.

[John Kelly]

Good advice generally from the posters here. Certainly do not try to add a soundpost as they are for violin family instruments which are very different in construction. As well as the mirror and light inspection (harder on a mandolin with its small body depth and very small soundhole), try tapping the top gently after loosening/removing the stringsand listeni for any sounds which might suggest a loose brace.

[Jim Garber]

Very cool. Would love to know whether the pick guard is real tortoise shell, and if the buttons are ivory.

I highly doubt that. This mandolin is prob from the 1920s or so. Pickguard would be celluloid and tuner buttons would be plastic. Some instruments from Europe would use TS and bone back then but very rarely those in the US esp more budget ones.

[fscotte]

Wasn't Martin using ivory saddles in the 20's?

[Jim Garber]

Wasn't Martin using ivory saddles in the 20's?

I think much earlier, tho if they were using ivory at all it would have been on the highest level instruments.

[Michael Lewis]

Martin used ivory for nuts and saddles on most of their instruments up through the 60s. Only the lower grade instruments like 15 and 17 series had ebony nuts.

[Jim Garber]

Martin used ivory for nuts and saddles on most of their instruments up through the 60s. Only the lower grade instruments like 15 and 17 series had ebony nuts.

Really? I would think that they would have used bone by the 60s if not before.

[Michael Lewis]

The first plastic nuts started in '73 replacing the ivory on the lower models (style 18, 21, 28), and by '75 even the D-35 had micarta nuts and saddles. It was ivory up until that time with some exceptions due to shortages of materials.

[hobe12]

Thanks for all the helpful advice. I brought it in to show a local luthier in NYC. I told him I was interested in learning how to do repairs and he is guiding me through the process of fixing it. Upon his suggestion, I removed the top and found the loose bracings. I removed them and made some new ones. Right now, I have the top clamped flat with the new braces drying, so hopefully, that will address the sinking. Pictures are below.

[Bill Snyder]

Did you make the braces absolutely flat? I don't know what this instrument had but generally flat tops are not absolutely flat. They have a bit of an induced arch to them. Without it they are not as strong and they can easily end up concave.
The first mandolin I built 9 years ago has flat braces and it is still playable but it appears to be a tad bit concave around the bridge.

EDIT: In looking at the first photos you posted again it looks like this top might have been built with a slight cant to it. Was it?

[hobe12]

Hi Bill,

Yes, I did make it flat. I figured trying to make an arch was a bit ambitious for my first project. When I inspected the insides, I noticed a cut in the top right along the middle brace on the tailpiece side. When I put in new braces, I put one over the crack because that's where the top was caving in. Thanks for the help.

Sam

[hobe12]

Hi Bill,

Yes, I did make it flat. I figured trying to make an arch was a bit ambitious for my first project. When I inspected the insides, I noticed a cut in the top right along the middle brace on the tailpiece side. When I put in new braces, I put one over the crack because that's where the top was caving in. Thanks for the help.

Sam

[hobe12]

Is there any way I can still make the cant?

[bmac]

that should not be a problem.... remove the braces and using ilke 100 grit sand paper taped to a flat surface sand each brace with a given number of passes over the sand paper using pressure on each end separately... IE... 20 passes with pressure on the right end and 20 passes with pressure on the left half... Obviously the center should receive the least sanding and the ends the most... Simply repeat the process until you have an arch of desired dimension.... do on remainder of braces. I would assume that the center of the arch should be roughly 1/8" more than the ends.... I may have phrased that poorly but I think you get it.... as long as you count the number of passes on each end and keep your pressure toward the ends of the braces you should do fine.

As long as you count the number of passes on each side of the brace then each brace should come out pretty similar... Keep the pressure consistant too... and hold brace firmly while sanding because you retain a flat surface on the brace, not a rounded surface.

You will have the best results by taping down the sand paper and sliding the brace on it.... not holding the brace and sliding the sandpaper over it.

[Pete Jenner]

Good advice from Bart there. Hobe12, you may be well served to read this thread by luthier Martin Jacobson.

[bmac]

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[hobe12]

Thanks for all the great advice. This was a really fun first project and it turned out really well. The collapsing reversed and even with the new chunky braces I added, the mando retains its deep old time sound.

Does anyone have any suggestions on how I may go about finding a case? I believe its a 1915 era Washburn, but it is considerably smaller than my normal F and doesn't fit in the case I already have.

Pics below: