Bowlback Restoration Tips?

[Matt DeBlass]

I've been craving both a bowlback and an inexpensive project lately, so I picked up an old mandolin in need of some serious TLC. It's got some separated ribs and a few cracks in the top, etc.
I"m not expecting miracles, from an economic standpoint it's probably not worth fixing, but I like to tinker and have just enough knowledge of instrument repair to get myself into trouble.
I was wondering, though, if there were resources with information related to fixing up vintage mandolins? For example, it looks like I'm going to have to remove the top to repair some of the damage, so would I be best off using steam, or just heat or a sharp knife and a lot of patience? And how about he fretboard?
Just a few pointers would be great. At the moment, because I'm somewhat underemployed, I have plenty of free time (but little money) so I'm in no rush.

[brunello97]

Well, Matt, I have been down the road a bit for many of the same sounding reasons that you have described: to keep my hands busy, learn how these instruments were made, fit up a few and maybe even wind up with an instrument I couldn't afford 'whole'. All of that has worked out for me, including a few disasters and a lot of mistakes along the way. Trolling the 'bowlbacks of note' thread for discussions on repairs helped me a lot. Our friend, Dave Hyndes, who is a wizard at this has been amazingly generous with his advice and information and has posted numerous photo essay/threads on some of his repair work. Check out Dave's website as well and his 'mandolin hospital' page. Another MC amigo, John aka "Tavy", also does great bowlback restoration work and has a few threads showing his projects. Searching for their posts will turn up a wealth of information. Lots of useful information in the 'builders' section, a bit on bowlbacks but a lot of useful information that you can extrapolate from archtop or flattop repair as well. Getting a top off a bowlback isn't that hard. I would avoid steam if at all possible. In some cases the hide glue joint simply releases under a careful bit of leverage with a thin blade or the classic two blades in opposition. I have used a clothes iron to good effect (well padded so as no to scorch) to warm up the old glue before working the top off. Go nice and careful where the top attaches to the neck and heel block-much more glue there. With most US made bowls the fretboard is thick enough to remove intact but I have found it easier with Italian bowls (and their thin fretboards) to simply remove a fret and cut through and take the top and fretboard off as a unit. Sometimes that isn't possible.......In any event take it slow and easy. Dave and John are great guys and do wonderful work and are very accessible so check out their contributions here and don't be afraid to contact them.

Mick

[Matt DeBlass]

Thank you! I've actually managed to get the top off using the "thin blade and lots of patience" approach, though the fretboard was cracked a bit and ended up coming apart where the neck joins the body (fortunately it split right along a fret slot, so I think I can salvage it all). The poor thing has lost its label, but judging by the pickguard (or what's left of it) it's an entry-level Lyon and Healy.
I'll look up John an Dave as I get going on the project, and maybe even post a few photos of my own.
I have to say, it may never be a top-quality instrument, but I'm having fun with this.

[Jim Garber]

Not being a serious expert on these matters, I would think that you may be better off replacing the whole fretboard than trying to refret one that broke off. I hope the luthiers chime in here. But do keep us apprised of your progress. If I ever have any time I intend to try my had at some bowlback repairs. I certainly have many guinea pigs to experiment on.

[brunello97]

Matt and Jim, I have purchased pre-slotted fretboards from

http://www.allenguitar.com/fetbd_pre-slot.htm

and used them on some bowl-rehab projects. Some of our luthier friends may have other sources and certainly the skills to make their own (which I know I lack.) I have found the Allen boards to be quite accurate and made of nice slabs of material. I have turned a few MOR Italian bowls into nice playing instruments (to my ear) simply by getting them new fretboards so they intonate properly. The string slotting can vary so widely on some of these old ciotole del popolo. Fussing with new frets takes some time (I'm still learning) but it is pretty methodical and there is lots of good advice around. From the sounds of it Jim you have quite a herd there at the Double B Ranch.

Mick

[Jim Garber]

Mick: my main concern with Allen's fretboards would be that they are much thicker than some of the italian ones. OTOH tho that may be an advantage esp for instruments where the action needs to be raised. I can;t seem to find the prices for the custom ordered scales? Are they just the same but without any returns? Which do you order for our bowlbacks? 12.978" or 13.095" or something else?

[Schlegel]

Jim, You can check if this is exact for any particular instrument, but I find a Gibson scale board is pretty darn close if you cut off the first fret space, i.e. reset fret 2 to be fret 1. Convenient if you like zero frets.

[brunello97]

Jim, as Shlegel suggests, I've ordered the longer ones and then on their direction cut off the additional 'frets' to accommodate the instrument size. Don't ask me about the math. It has worked out more than fine. They are certainly much thicker than the original Italian fretboards but as you say that thickness has proved helpful in adjusting for neck angle issues. It sure beats shimming them as I have tried in the past. I've built a simple little jig to help set the taper angle and then just sand it to the desired thickness on a 'shooting board' of some sandpaper glued to a long board. It works surprisingly well. (I can send you photos, or the jig itself if you want......I use if for leveling frets as well.) If you scroll down to the 'ebony mandolin' you can find the unit price (I think.) Their website has changed since my last order-I bought a number at once-but I have found them very helpful on the phone. If the neck on the bowlback was in good shape and the intonation was good, I would use the 'sever the fretboard' technique that Dave Hyndes uses and cut the fretboard at a fret joint and remove the top accordingly (with remaining fretboard attached.) It sounds as if this is what Matt was trying to do. No joke, this modest Lanfranco I am playing now sounds great with a proper fretboard. I offered it for a silly price to a guy here on the MC who was looking for an Italian bowl. He got squishy about it and sent it back. My charmed life. I've been in bowl heaven with it for months and can't wait to invest in a proper Italian one. I can only imagine how good that will sound. You must be really enjoying yours (and that Vega as well!)

Mick

[Tavy]

Re: split fingerboard - pictures would help - but if it's split where the body/neck join is then that's perfectly fine, as one accepted disassembly technique is to cut through the fingerboard there anyway (with 10th fret onwards remaining attached to the now removed top). The trick is getting the top back on in the right place so the intonation still works out OK past fret 10 - in particular watch out for top slippage/movement after you have have everything glued and clamped up.

BTW although a new fingerboard with nice new shiny (round!) frets will give you a good playing experience for sure... there's no reason why the old fretboard shouldn't do just as well... especially if you take the frets out and level the board - then either re-insert and level the old bar frets (for max authenticity) - or if it's a no-value bowl - shim the slots and insert new fretwire. Take your time getting the frets absolutely dead-level and you'll be rewarded with the ability to take the action down low and really enjoy the instrument. Oh... and be prepared to redo your first fret job 6 months later when you grow dissatified with it... nobodies perfect first time round

HTH, John.

[Mike-D]

Great tip about cutting off the first fret space. I'll check the math but it sounds much simpler than slotting my own frets.

Stewart MacDonald has slotted fret boards too. I don't know how they compare to the Allen ones.

Mike

[brunello97]

I can't help with the Allen v Stewart MacDonald fretboards. But I assume that they would be comparable. The ebony ones I got from Allen were exceptionally good. Great wood, great quality. The issues with the ROTM Italian bowls I have seen is that they can be on or way, way off. The latter of which can make for extremely frustrating playing, but I have grown very fussy about that.

Getting a sense of fret-spacing/intonation quality of the existing fretboard is important before banking on a replacement strategy. If it isn't playable, you can comp it against a fretboard you know is proper. John is absolutely right. If the fretboard is good, then by all means try to save it. Those wafer thin Italian boards are special. The lift-shim-refret method is time consuming, but no more so than installing frets in a new board. Whichever path you take it will be rewarding. These old bowlbacks, no matter how modest, sound great to my ear with proper intonation, good strings and playing technique. I've figured out how to control the first two variables. The third one is more elusive......

Mick

[brunello97]

I can't help with the Allen v Stewart MacDonald fretboards. But I assume that they would be comparable. The ebony ones I got from Allen were exceptionally good. Great wood, great quality. The issues with the ROTM Italian bowls I have seen is that they can be on or way, way off. The latter of which can make for extremely frustrating playing, but I have grown very fussy about that.

Getting a sense of fret-spacing/intonation quality of the existing fretboard is important before banking on a replacement strategy. If it isn't playable, you can comp it against a fretboard you know is proper. John is absolutely right. If the fretboard is good, then by all means try to save it. Those wafer thin Italian boards are special. The lift-shim-refret method is time consuming, but no more so than installing frets in a new board. Whichever path you take it will be rewarding. These old bowlbacks, no matter how modest, sound great to my ear with proper intonation, good strings and playing technique. I've figured out how to control the first two variables. The third one is more elusive......

Mick

[Matt DeBlass]

I still haven't decided on the fretboard, but I'm leaning towards replacing it. It's fairly thick and American (no label, but by what's left of the pickguard inlay and the general design I think it's an entry-level Lyon and Healy) but there are a few chunks missing and it's curling up at the edges. The frets are a bit loose as well and one is missing.
So far the repairs on the top have gone brilliantly. Using info from the Mandolin Hospital site I've repaired the sinkage and a crack around the soundhole and added some extra bracing to stabilize it. It looks good and feels solid.
The bowl has been reglued, but I still have some gaps where the ribs shrunk at different rates. I'm probably going to have to put some extra wood in one of the gaps, but the rest are small enough for a bit of putty.
I'd love to see that fretboard jig you've made!
This has been a lot of fun so far.

[Tavy]

The bowl has been reglued, but I still have some gaps where the ribs shrunk at different rates. I'm probably going to have to put some extra wood in one of the gaps, but the rest are small enough for a bit of putty.

Just a word of warning - if the sound chamber is "leaky" - i.e. if there are holes/gaps anywhere (other than the sound hole obviously!) it can quite noticably harm the sound quality. If you can possibly help it, don't use wood putty anywhere either - it's tempting but no matter what you do it'll alway end up looking like... well wood putty Shellac mixed with wood dust and/or pummice stone makes good filler that'll match the surrounding wood, and be easily reversible by the next repair guy if need be as well.

HTH, John.

[billkilpatrick]

john - the new/old bowlback i just bought has a partial, hairline separation at the back of the bowl, where the widest strip of wood connected to the top is connected to the progressively thinner, descending pieces of the wooden bowl. staring into the bowl when placed in front of a light source looks a bit like a range of lights from of a small desert town in the dead of night. if i understand you correctly, a paste made from shellac mixed with wood dust, smeared along the crack (luckily there only appears to be one) should seal it without causing a huge cosmetic disaster.

if that's correct, the only problem i have is finding somewhere local that sells shellac - i don't think there is one. is there an acceptable alternative to mix with wood dust? - something "easily reversible" should things go wrong?

[Schlegel]

john - the new/old bowlback i just bought has a partial, hairline separation at the back of the bowl, where the widest strip of wood connected to the top is connected to the progressively thinner, descending pieces of the wooden bowl. staring into the bowl when placed in front of a light source looks a bit like a range of lights from of a small desert town in the dead of night. if i understand you correctly, a paste made from shellac mixed with wood dust, smeared along the crack (luckily there only appears to be one) should seal it without causing a huge cosmetic disaster.

if that's correct, the only problem i have is finding somewhere local that sells shellac - i don't think there is one. is there an acceptable alternative to mix with wood dust? - something "easily reversible" should things go wrong?

Bill, Dave Hynds sells small amount of shellac flakes which he will ship and you can mix in alcohol yourself. It's on his website under Restoration Parts.

[Tavy]

john - the new/old bowlback i just bought has a partial, hairline separation at the back of the bowl, where the widest strip of wood connected to the top is connected to the progressively thinner, descending pieces of the wooden bowl. staring into the bowl when placed in front of a light source looks a bit like a range of lights from of a small desert town in the dead of night. if i understand you correctly, a paste made from shellac mixed with wood dust, smeared along the crack (luckily there only appears to be one) should seal it without causing a huge cosmetic disaster.

if that's correct, the only problem i have is finding somewhere local that sells shellac - i don't think there is one. is there an acceptable alternative to mix with wood dust? - something "easily reversible" should things go wrong?

Pictures might help - but if I understand you correctly the ribs are still glued together (ie no movement possible between them when you press with your fingers), but there are some pinhole gaps in the glue line? The reason I ask about everything being solid, is that if any part of the instrument is "flapping in the breeze" then it acts as a damper rather than a sound producer, sucking some frequencies out of the instrument. Hope that makes sense.

I can't think of anything else quite as good (and gooey!) as shellac that I would recommend. If you PM me I can mail you some flakes - but you'd still need to buy the alcohol - so try having a look around your local DIY stores - some will store ready mixed shellac in small bottles (look for "French Polish"). It's not ideal 'cos it goes off in solution after a while, but if you pick on a large store in a big town with a high stock throughput then it should be good enough for that purpose.

Basically, you poor some out into a small plastic bowl (or similar), then mix in the wood dust and wait till it's thick enough to push into the gap with the tip of a screwdriver. Ideally you want to use the same wood type as the instrument's made from, but be aware that the result will be darker in color than the wood dust, and the smaller the dust particles the darker it gets - almost black for finely powdered rosewood. For that reason I also tend to mix in pumice stone to "dilute" things a bit so it's the right color.

So I guess if you need wood dust and pumice as well, you'd better PM me after all!

[Tavy]

Forgot to mention - if the only thing you're missing is some colourless packing (the pumice), then in principle any colourless mineral will do. So bicarbonate of soda, talcum powder, maybe even salt at a pinch (might be too course though, and maybe not inert enough for long term use?).

HTH, John.

[billkilpatrick]

thanks guys - as fate would have it, i had to drive to a town nearby and passed one of those little hardware stores, about the size of a broom closet, that (i think) only exist in italy - they had everything. all i need is a piece of dark wood to collect dust from and i'm away.

long life to the internet, the mandolin cafe and all its denizens therein!