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May 30, 2020 - 9:06:57 AM
10 posts since 5/16/2020

Hi all,

Came across a road block in assembling an instrument.
Ribs were alligned and attatched to back. When placing the front plate, I noticed a pretty big gap in one of the C bouts.

I was thinking an inveserse clamping spool with wing nut in the middle to push the rib out, but I'm pretty sure it wont set unless it's ironed and reset that way. Would a hot towel help? Is there a recommended way to correct this?

This did not come out of a violín mold. The other c-bout front side lines up fine. The view is from the back of violin looking at the backside of the top plate.

Thanks,
J


Edited by - Johnny_Mariachi on 05/30/2020 10:16:51

May 30, 2020 - 11:29:42 AM

195 posts since 3/1/2020

It’s hard to tell what’s going on from the picture. Can you take more that show better views?

Is the rib warped? If it is, it may need to be corrected. Don’t just add a hot towel. That can cause the rib to warp badly.

I can’t tell exactly, but it doesn’t look like you have the rib mitres aligned with the top’s corners, and the lower mitre appears to have separated.

May 30, 2020 - 12:52:49 PM

10 posts since 5/16/2020

The ribs have been glued to back side. That looks and aligns fine. When dry attaching the front. This c-bout is the only area not cooperating. It's possible it was warped to begin with, I didn't notice until the point of attaching the front. The left side of violin (not pictured) is fine.
The top right area seems to align as well as the bottom right, but the problem area is obvious. If I move top plate to the left, it will throw off alignment on left side of violin.




May 30, 2020 - 1:14:21 PM

1794 posts since 8/27/2008

How did you start this project, with both the top and back off? Judging by the varnish line the rib is clearly distorted from where it used to be. I'd be reluctant to try to force it out that far because it probably doesn't want to go. Not sure what's going on but you might have to remove at least part of the back to see. Even though you say the back is well located something is wrong.

If the rib is willing to move without undue stress it's possible you could pre-clamp that side in position, then loosen a couple clamps at a time to get glue in with a knife. Let it set overnight then do the same to the rest of the top.

Edited by - Brian Wood on 05/30/2020 13:26:08

May 30, 2020 - 2:00:45 PM

10 posts since 5/16/2020

Additional info and pics:

Front and back were originally separated. I started off by glueing frame to back. It looked okay, but this rib is way off when dry assembling the top. If I separate the entire frame or entire right side and somehow reglue, how to ensure alignment with the top plate in that one area?

Thanks, J

Ps: Rib is separated from that one corner block due to my experimental attempt to straighten out that area. Easy enough to fix that, but my issue still remains.


Edited by - Johnny_Mariachi on 05/30/2020 14:08:51

May 30, 2020 - 4:46:40 PM
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1794 posts since 8/27/2008

quote:
Originally posted by Johnny_Mariachi

Additional info and pics:

Front and back were originally separated. I started off by glueing frame to back. It looked okay, but this rib is way off when dry assembling the top. If I separate the entire frame or entire right side and somehow reglue, how to ensure alignment with the top plate in that one area?

Thanks, J

Ps: Rib is separated from that one corner block due to my experimental attempt to straighten out that area. Easy enough to fix that, but my issue still remains.


Have you tried to clamp the problem area first with several spool clamps, then try pulling and clamping the rest of the top? (Do it dry). If that doesn't work any better then it seems there is a twist in the ribs from gluing on the back, even though you can't see where it is.

If you end up having to take the back off again I would experiment with clamping on both sides dry until you understand what's going on.

May 30, 2020 - 6:11:45 PM

276 posts since 1/5/2009

I think your issue is a combination of things that have taken place. The C bouts tend to loose their shape if not held in a fixture. The upper and lower bout sides are also out of position slightly causing the C bout to bend inward. This is what caused the miss alignment. You should take the problem side ribs loose from the back and slowly reshape the rib garland to its original position. Wetting with any kind of water will make the material more flexible, but it will also loose shape as the humidity drops. Now you stated that the opposite side is not giving you any problems. I would suggest that you use that side to make a fixture that will fit the shape inside ribs between the linings. Then use that shape to correct the side that is giving you problems. After your done reshaping (dry) set the instrument aside after clamping top and back in place. This will take about 24 - 48 hrs. Then reglue the back in place.

May 30, 2020 - 6:21:24 PM

195 posts since 3/1/2020

Are you certain of the orientation of the ribs? If your rib structure is upside down, that could cause things to get out of line.

May 30, 2020 - 8:48:31 PM

1794 posts since 8/27/2008

quote:
Originally posted by The Violin Beautiful

Are you certain of the orientation of the ribs? If your rib structure is upside down, that could cause things to get out of line.


Good thought.

May 30, 2020 - 9:04:19 PM

10 posts since 5/16/2020

Regarding Orientation:.
I based it on the matching color stripe. I tried the other way, just in case. The inner lining didn't match up to the corner block, if that makes sense.

I originally glued the rib frame using the old varnish color line as my guide.

Anywho, problem rib has been removed. It seems straight and doesn't appear warped. I placed it on top of opposite c-bout and it lines up nicely. Will tackle problem later. Allows some additional suggestions to chime in. Also don't want to reglue and end up back where I started.

Thanks all,
J


May 31, 2020 - 6:26:15 AM

853 posts since 1/25/2008

I the top flat? If the top isn't kept clamped to a flat plate while it's off the instrument, it can warp. Check it by putting it on a flat surface. If it is warped, it can be flattened with a slight amount of moisture, and by clamping it to a flat surface for a week or so.

Jun 8, 2020 - 6:46:37 PM
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10 posts since 5/16/2020

Update:
Seems the issue was some bump/hump on the corner block. It was not perfectly flat and had an obvious rocking motion. It must have been 'rocked' inwards when back was glued. ???? Mystery solved.

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