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Joining two cello ribs


bcncello
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I'm repairing a student cello of my own (and on my own :)). The reparation consisting on redoing the neck block again, so I took off the neck, the previous neck block and the two upper ribs as far as to the upper C-bouts.

post-29934-0-28392300-1326541406_thumb.jpg

post-29934-0-94203900-1326541422_thumb.jpg

Now I'm in the process to graft a piece of new rib on both end of the two upper ribs (where they reach the neck block) and the question is how to make the graft. I thought of two ways to do so as shown on the attached image (the ribs are shown from above), and I suppose the first way should be the most suitable?

post-29934-0-49976300-1326539478_thumb.jpg

On the other hand whether one way or the other, which would be the best way to thin the ribs on the joining section so to achieve a best match? (remember it is a cello rib ;))

Thanks for your comments,

Rafael

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A long scarf joint like you drew has the problem of the thin outer edge being delicate and hard to blend in without getting wavy. Since this repair is over the block, you don't really need the added strength or headache of the scarf. A butt joint would work here as well as it would at the lower rib joint. Maybe a mild scarf to make jointing a little easier. Also, how much do you have to add? There isn't going to be much left after the neck is set, I'm guessing.

The butt or mild scarf joint can be fit with a block plane. The next question you have is how to glue it up. I'd glue the new piece on after gluing the rib to the block. You have more control that way since you don't have a few moving parts to deal with. Just be sure to clean out any squeezed out glue when you glue the rib on. I'm sure that there are those that can do it all at the same time or maybe use the tape trick.

Hopefully someone who as actually had to do this repair will pipe in and help you out. I've only had to shorten ribs.

--Joe

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I don't think that he's talking about damaged ribs. It's just some filler pieces on the side of the neck. Which, I'm actually surprised that it's going to need assuming you're putting in the original neck. But you're the one looking at it so I'll trust you.

If you do the graft as Weisar describes, it's a 25mm long joint. You'll be removing a bunch of original wood from the rib which will then be replaced with the new wood. By the time you reset the neck, you'll have a few mm of new wood showing. I'm not sure that this is the best approach. On a less than valuable instrument, it's a bunch of extra work for little gain. For a valuable instrument it's removing a lot of original wood which isn't in the best preservation practices.

Another thought about the scarf is that you'll have 25mm of *rib glued to rib glued to block* instead of just *rib glued to block*

Just my observations.

--Joe

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A long scarf joint like you drew has the problem of the thin outer edge being delicate and hard to blend in without getting wavy. Since this repair is over the block, you don't really need the added strength or headache of the scarf. A butt joint would work here as well as it would at the lower rib joint. Maybe a mild scarf to make jointing a little easier. Also, how much do you have to add? There isn't going to be much left after the neck is set, I'm guessing.

The butt or mild scarf joint can be fit with a block plane. The next question you have is how to glue it up. I'd glue the new piece on after gluing the rib to the block. You have more control that way since you don't have a few moving parts to deal with. Just be sure to clean out any squeezed out glue when you glue the rib on. I'm sure that there are those that can do it all at the same time or maybe use the tape trick.

Not sure I'd bother on a student Cello unless you're doing it for expereince.

For a proper 'hole in the rib' type repair, you can follow the Weishaar book, it's worth buying.

Joe, Ben thank you very much for your help. Actually I'm doing practicing here :)

I decided reseting the neck block because the neck heel was extremely low. I took it off and added a piece of maple on its base as an extension, but once I would set it into place there would be some mm distance between the neck heel and the ribs end, so the ribs extension neded.

Afer reading your posts I think just a butt joint would perfectly do. I named that cello "humpty dumpty", and in case I'm able to bring it back to live I would rename it :P

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No. The idea is to remove as little wood as necessary. Just clean up the ends of the original ribs to make them straight and crisp - but retaining the existing angle. If, in fact, you are only going to have a couple of mm of filler strip showing in the end, consider orienting your filler pieces so the long grain goes from the top plate towards the button. This orients the grain perpendicular to the ribs so it's not as invisible, but it will be much easier to work the filler and it will, imho, be better than a very thin strip that is entirely cross grain. A tight fitting joint and a little creative touch-up and it will be hard to see. It'll be like when a neck mortise is filled for a neck reset and a thin sliver of the filler block is left visible after the neck is in.

A mild scarf is a good thing and after re-reading Ben's post, he said "Hole in the rib" and I was too quick to notice it. Sorry Ben! This is actually a gentler scarf than a graft. A gentle scarf _can_ make the fitting a little easier (if he rib is flat). If you make it so the outer part of the rib is the long part of the scarf, it can help lock in the little filler piece. Just something to consider. A 90 degree will be the simplest and will be the least effected by any irregularities.

--Joe

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