g-flex 655, ie, the thickened one.
Yes scrape off the finish as you describe, apply the g-flex which does not need to be "wet out" like 105 resin...just g-flex right on the woods. Tape it out beforehand on the panel and rib so it doesn't get everywhere, tool it into a cove with a Popsicle stick or thin stick you had sanded into a radius. Then immediately remove the tape. Don't leave the tape on while it cures...clean up will be a disaster. If you tape it out and remove the tape after tooling, there will be no secondary cleanup work.
We are reducing the radius with each iteration of this. We started with 1/4" radius, and are reducing it to 3/16 or so. Its important to do the fillet on both sides of the rib, the entire length of the rib. 655 is thickened, so it doesn't run, but I would flip the piano so you are working flat instead of vertical, as it may run a little on the vertical.
If the rib is unglued in parts, before gluing, using a multitool with a 90 deg blade, kerf the failed glue joint, only at the failure, to new wood. If the joint has not failed, don't bother kerfing. When and if you kerf, you have to force the glue into the kerf, it will not run by itself. No screws of clamps necessary when we do it. However, I have not done it on a board that has seriously failed and the panel is curving away from the panel. If this were the condition,. I would toss the board. I only do this on reasonably intact old boards with some some cracks and separation, but where joint separation is not so bad the panel is peeling away at the crack. The ones we have done had either no cracks, or 2-3 major long cracks and some smaller cracks. We don't bother about crown.
Regarding panel cracks, as opposed to rib/panel cracks, just open them up with a saw kerf to new wood, or with a utility knife, and fill, using west 105 resin and fast hardener, thickened with flour or one of their fillers. Tint the epoxy with Transtint dyes, to color the epoxy to match the wood. Protect the panel with tape, so cleanup along the crack is easier. If its an upright, and cosmetics are not important, skip the tinting. You could use g-flex in panel cracks, but I would probably put some tape under the joint so it doesn't make a mess on the other side of the panel. 105 and thickener is cosmetically nicer than the g-flex, so if its a grand, that's why I use 105 instead of g-flex on panel cracks.
I don't screw or clamp. If the separations are that bad, and it would be a mess without screws or clamps, I'd toss the board.
The idea for this was not so much about fixing really beat boards, as it is about renewing panel stiffness in a board that has gotten tired. My theory is that the old rib to panel joints even if not obviously failed have a degraded glue substance in the joint which has not catastrophically failed yet. It has not separated visually, but if one were to separate the rib and panel, one would probably see half of the original hide glue substance had powdered away. This is why I glue along the entire length of the ribs on both sides. You are renewing the old, degraded glue joint along the entire rib, not just at crack points. Doing this, along the entire rib has created for me seriously musical old boards, including one I kept as my own piano...and is one of the nicest sounding pianos I have played....vintage Chickering, original board.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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Original Message:
Sent: 01-22-2021 19:43
From: Laura Wright
Subject: Rib re-gluing
Jim,
If I understand correctly, you scrape off the old finish from the sides of the rib and about 1/4" on the panel surface, then apply the G-flex and cove it with some sort of radiused tool. I am unfamiliar with the consistency of the g-flex material, is it thick? Or is it thin enough to run under the rib where it is unglued? Do you purposely try to work some under there? Are you using any kind of screws or clamps?
Also, is it the g-flex 650 or 655?
This does sound like less work than the old glue and screw method.
Thanks!
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Laura Wright, RPT
Ivory Keys Piano Service
Durango CO
Original Message:
Sent: 01-20-2021 16:25
From: Jim Ialeggio
Subject: Rib re-gluing
FYI, I no longer kerf the rib/panel joint. Instead I simply scrape the panel and rib, both sides of the rib, to get about 1/4" scraped surface, and apply a fillet of West system G-flex along the entire length of both sides of the rib. Way easier, and I think actually better than compromising whatever is left of the existing original glue joint.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 01-20-2021 13:13
From: Floyd Gadd
Subject: Rib re-gluing
If you haven't already done so, I encourage you to read over some posts by Jim Ialeggio in regard to soundboard/rib joint renewal. I have found them most helpful:
https://my.ptg.org/communities/community-home/digestviewer/viewthread?MessageKey=38690406-2395-41a2-b9da-cace7b85bbf4&CommunityKey=6265a40b-9fd2-4152-a628-bd7c7d770cbf&tab=digestviewer#bm38690406-2395-41a2-b9da-cace7b85bbf4
https://my.ptg.org/communities/community-home/digestviewer/viewthread?MessageKey=39d3b811-c41a-428a-a970-011c1840c360&
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Floyd Gadd
Regina SK
306-502-9103
Original Message:
Sent: 01-20-2021 11:30
From: Peter Grey
Subject: Rib re-gluing
Laura,
I have done it both ways, and would do as the circumstances permit. The issue is generally a cosmetic one in that it is hard to get sufficient grip of the screw threads (from the back) without penetration the surface of the SB. But from a functional standpoint I see no difference.
Plus, even with strings removed, the plate may still get in the way of some fasteners from the front side. So, 6:1 - 6:the other. Sometimes it's necessary to do a combination of both.
Pwg
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Peter Grey
Stratham NH
603-686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 01-20-2021 11:06
From: Laura Wright
Subject: Rib re-gluing
Hello all,
If you are re-gluing ribs from the back (upright piano) with the screw method, does it matter if the tension from the strings is there or not? I'm working on an old upright that I will be restringing, and there is some rib separation that needs attention. I was just wondering if it's better to do it before or after I remove the old strings. In the past I have always removed the strings first, but I was wondering if it actually makes any difference.
By the way, there is good crown in the board according to the thread method.
Thanks!
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Laura Wright, RPT
Ivory Keys Piano Service
Durango CO
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