L&H bowlback repair

[PaulD]

I've mentioned in a couple other threads that I recently acquired a Lyon & Healy bowlback that needs help, now it's probably time to start asking questions rather than hacking through like I've done in the past. I'll post a few pics when I can.

The instrument is pretty complete but has suffered from dehydration. The top has a crack and there is one glue joint between staves that is open. The fretboard has shrunk to where I think it's not salvageable; the bar frets are protruding quite a bit and they've broken the ivoroid binding on the treble side. The fretboard also has quite a few cracks. I will also need to make a bridge, so I'm looking around for what the bridge should look like.

First off; the top crack. The top has shrunk (as they do) and had one sizable crack from the tailpiece to the lateral brace, but the brace seems firmly attached. Some texts I've read recommend gluing a sliver of wood into the crack, but I've always figured if I can get it to close up I'm better off. Flawed thinking? 3 weeks of gradual rehydration has all but closed the crack up and I'm sure I can get it to close the last little bit.

If I can get this crack to close and get glue in there, should I also reinforce it from behind? I've never had to reinforce a repair like this, but this one was more open than others I've done. If I'm going to reinforce it I'm thinking I should do it before I close up the back since I can get in there with a thin implement right now. I was originally going to glue the back first.

You're advice is appreciated... I'm sure I will have other questions, or I'll at least post on how it's going.

Paul Doubek

[dave17120]

Hi, some interesting ideas there!
If you re-hydrate to close the crack, what happens when it dries out again? I reckon you can't combat shrinkage, you have to go with it, so I'm of the 'fill it with a sliver of old topwood' persuasion. I also re-enforce underneath. I suspect with rehydration and re-enforcing, once it dries out again, it'll go somewhere else.
I shall be interested to see the pictures.
Dave

[Martin Jonas]

You may be interested in these (http://mandolinrepairs.finelutherie.com/) photos that Jon Springall put up, showing his repairs of my 1898 Vinaccia bowlback. These include several top cracks, which he fixed completely invisibly.

Martin

[Jim Garber]

I will also need to make a bridge, so I'm looking around for what the bridge should look like.
The bridges varied greatly on L&H bowlbacks. Post a photo of your L&H. Is there a model name/number?

I have a large collection of jpegs of bowlback mandolins and can prob send you the appropriate pic to work from.

Jim

[PaulD]

Thanks Dave and Martin... I appreciate the input. WRT rehydration I hoping my logic isn't flawed, but it goes something like this;

I don't want to "overhydrate" (is that a word?) the instrument... I'm shooting for getting somewhere above 50% and I'm trying to get it there gradually so as not to create additional problems. If the crack doesn't close up completely using humidity I'll put a sliver in there. After the instrument is repaired my intent is to keep it in the 40%-45% RH range so that it is not subjected to the shrinkage that caused the crack. I agree with your logic that if it shrinks with the crack reinforced I would expect a crack to open up somewhere else.

My concern, maybe unfounded, with putting slivers in is what happens if the instrument is then stored at proper humidity? If the crack/sliver is thin it's probably fine... if it's wider could the top buckle? I don't know... I'm trying to figure this stuff out. One guitar repair book I have (Sloane?) claims that when the wood has shrunk to the point of cracking the cellular damage is permanent and it will never return to its original state, in which case putting the sliver in or extending the edges as in Martin's repair are the only solutions. One nice thing is that the instrument is mine... I'll get to see and deal with the long term effects of my repair work.

I don't want to take the top off if I can avoid it, but I think I will try to reinforce through the opening in the back. The problem is (and I didn't expect this); the rehydration has apparently forced the instrument back into its original shape enough that the back is closing up as well. I'll have to insert some wedges in to hold it open enough to get some thin tools through.

Thanks again, the input is helpful.

Paul Doubek

[PaulD]

Jim; thanks... I'll get some pics up when I can. I was going to do it last night but other obligations consumed my time. The right half of the Lyon & Healy label is there... the other half went away when the back opened up. The couple of pics I've found that are similar (http://www.musicfolk.com/admin/popup.php?item=88&picnum=0) don't have enough detail to really make out the bridge. Better pics are greatly appreciated! http://www.mandolincafe.net/iB_html/non-cgi/emoticons/smile.gif

Paul Doubek

[Martin Jonas]

Paul: I think you may have misunderstood the technique used on my Vinaccia. The repair on the edge crack was unrelated to the crack in the lower bout and it was not caused by shrinkage. Rather, the purfling channel was cut too deep by the original luthier and eventually cracked right along the edge of the purfling, 3mm or so from the edge of the soundboard. That's why Jon had to underedge the soundboard. He has not, however, made it wider to compensate for shrinkage. The top cracks were closed with the clamps you can see in the photos, without either a wood patch or rehydration. This elaborate clamping arrangment makes it possible to pull the bits of wood into precisely the alignment you want for glueing. Obviously, you can't use this technique without taking off the top, though.

Martin

[Jim Garber]

Paul:
Here is a bridge with bone insert from an American Conservatory mandolin. From the pics you linked to, I would say that the bridge on that mandolin is a solid rosewood one without insert. Of course, it is hard to say whether that bridge is original either.

I can continue to check thru my files to see what would be the most sensible.

Jim

[PaulD]

Thanks again Jim- it all helps, and that bridge looks pretty easy to replicate. I may even go with the bone insert... I like the look. I will probably make the bridge out of the same ebony I'll use to replace the fretboard, but I might have some small pieces of Brazilian Rosewood large enough for a bridge.

Martin- I did misunderstand the underedging, but your explanation makes sense. Thanks for clearing it up. Apparently your luthier is going on a similar assumption to mine: if the crack is repaired and the instrument is then properly cared for (i.e. stored with adequate humidity) that the crack will not reappear. Maybe having removed and reinstalled the top relieves some of the tension created by clamping the crack as well.

pd

[sunburst]

Paul, you're on the right track.
When the instrument is properly humidified, if the crack is closed tight, you can glue it. If it isn't closed, over-humidifying is not a good idea because you'd be asking for trouble when proper humidity is restored, and even more trouble when the humidity is too low, as will almost certainly happen in the lifetime of the instrument. "Splinting" it with a strip of spruce is the better repair, in that case.

The top is not at all likely to buckle, and, in fact, the "splint" will probably be 1/32" or less thick.

I wonder if old tops that don't rehydrate to their full former size have been over humidified in the past and taken on compression set? That could be the case, and, even if not, I think it's safest to let the top be the size it wants to be at 40%-50% relative humidity.

(PS. Instrument tops tend to "bulge" with high moisture content and thereby relieve the compression. That keeps them from buckling, and likely keeps them from taking on compression set too, but I still wonder why some of them won't return to original size. Could be they were built too wet in the first place.)

[Jim Garber]

I think I found a pic of the exact bridge on a mandolin similar to the one you linked to.

Jim

[PaulD]

Thanks for the pic. I think that mando is a little fancier than the one I'm working on. I'm looking at mine now and the "shadow" of the missing bridge is square on the ends. Also, the inlay is an ivoroid type stuff (same as the fretboard binding) whereas the one in the pic looks like MOP. What's left of the label looks like it read

Made by
Lyon & Healy
Chicago, IL.
USA

No hint of a model number that I've seen yet.

I like the herringbone purfling on the one you've pictured. I think the first bridge you posted is probably close after looking at the shadow, but if I've got to build one anyway I might get fancier with it. I'll try to get some pics up tonight.

BTW: For anyone that cares. The quote I was thinking of about wood not swelling back into shape is from Irving Sloan's Guitar Repair. I don't know how much validity it has, but the text reads:


Wood that has cracked and gradully adapted to a new conformation has a memory. ... the wood will return to the conformation decreed by a long process of cellular and molecular adaptation.

He then goes into the process of inserting a splint into the crack. If he's right my attempts to repair the crack w/o a "splint" should likely fail... we'll see!

Thanks again for the help.

Paul Doubek

[Eugene]

That last bridge doesn't look like any suspected original that I've seen on a Lyon & Healy product.

[Jim Garber]

That last bridge doesn't look like any suspected original that I've seen on a Lyon & Healy product.
You may be quite right on this one. Just anoth4er case of mix and match. It is odd that som amny of these bowlbacks seem to be missing bridges or have replacements. Why is that? Most Gibsons seem to keep their original bridges. I guess just another case of bowlback abuse.

Jim

[PaulD]

Here are the pics of my project mando. Unfortunately my 2 Megapixel point and shoot camera doesn't have a decent LCD, so I end up with a number of images that I can't tell are out of focus until I get them into Photoshop. Hence the fuzzy images of the back (there was a lot of reflection with the flash so I shot them with the flash off). Anyway... it's enough to get an idea.

I don't think the crack is going to close up any more than it already is, so I will be splinting what is left. The Utah Instrument Builders meeting is tonight so I'll see if the host has some old spruce I can use to get close to the color. It won't be very visible behind the strings anyway.

pd

[PaulD]

The back, showing the separated ribs with the inset attempting to show a small patch of rosewood that is missing and some binding that needs alignment. Again, I'll see tonight if Tom has some rosewood that's a close match.

pd

[PaulD]

Lastly, the peghead and fingerboard. The binding on the bass side and end of the extension is intact, but it's missing about 2/3 of the binding on the treble side and the frets are pushing out what's there. I plan on replacing the fretboard, probably going with some thin T-fretwire rather than the bar frets; although they are all there and in servicable shape... I guess I could reuse them.

pd

[Jim Garber]

The Utah Instrument Builders meeting is tonight so I'll see if the host has some old spruce I can use to get close to the color.
Paul:
If the host has nothing for you, PM me. I have a basket case Vega that I can easily cut a few pieces of spruce and rosewood and mail off to you.

Jim

[PaulD]

I appreciate the offer Jim... I'll let you know. Tom Middlen at Local Music is a packrat of all things instrument related- I'm sure he will at least have some old spruce. Is there a "typical" wood that would have been used for the white stripes between the ribs (staves)? I figured it was either maple or holly. I was also surprised to find that the ribs have a slight rabbet or ledge to receive the stripe. I don't know if that's typical but it's going to make the back repair easier.

pd

[Jim Garber]

I believe that Eugene noted that some of the lower-end L&H mandolins had pseudo-ribs. In other words there were less ribs since some were just inlaid with a stripe to look like separate ribs.

Jim