Yamaki 331s top replacement?

Stray Feathers
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Re: Yamaki 331s top replacement?

Post by Stray Feathers »

I removed the top on this guitar today, which went without incident (phew). The x-brace, as I suspected, is barely 3/8" deep at the x-joint, which may have contributed to the bridge belly. You can see the economies of commercial production inside, e.g the end blocks have grain perpendicular to the sides rather than parallel, but then, the sides are laminated so it may not matter.There are a couple of braces that were loose. I was concerned that the headblock might be loose but it seems okay, except there is a gap where the back sits on it. I may glue in a tapered shim there. Two of the back braces look really clunky and I wonder if it is worth trimming them some. There is a piece on top of the neck block that runs under the fretboard extension; it seems solid so I don't know if there is any point changing that. Kerfing may be a little thin so I will have to watch what binding I use. I don't know what glue was used - it seems to have dried white. But this guitar is not worth deconstructing and regluing so I guess I will take my chances. Next step: make a new top . . . Bruce W.
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Last edited by Stray Feathers on Sat Dec 09, 2023 6:01 pm, edited 1 time in total.
phavriluk
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Joined: Mon Jul 09, 2012 9:49 pm

Re: Yamaki 331s top replacement?

Post by phavriluk »

This project can stimulate any number of suggestions, so here's one from me: The kerfing looks triangular, so that triangular kerfing can be attached to the existing topside kerfing upside down, which will give the effect of reversed kerfing, i.e., the connecting strip will be the first part of the kerfing that can be seen, and that will go a very long way to stiffening the rim and it will remove any doubt about the kerfing's contribution to top installation and will support just about any choice of top purfling.

Just a thought...
peter havriluk
Stray Feathers
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Re: Yamaki 331s top replacement?

Post by Stray Feathers »

A new Western Redcedar top is ready to go on this Yamaki. I hoped I could use my dreadnought mould to hold the body while I worked on it, but no. The lower bout is wider, and the upper bout narrower, than a dread. So I used a cradle which worked fine. The original top was very thin for cedar - about .100" including finish, which must have contributed to the bridge belly. The new top is .123" and still seems stiff, and the braced top rings nicely. The bracing is a more normal size, about 5/8" tall at the X, and I have scalloped most of them to lose some weight. I did put in a popsicle brace to lessen the chance of splitting at the fretboard extension, which was one of the problems with the original top. I slotted the extension of the neck block to accommodate it. There were a few bits of kerfing that needed re-gluing, so yes, it was an inexpensive guitar. After using a 28' radius sanding dish on the rims, the top fits well and the plane of the upper bout lines up well with the bridge (phew). I'll leave the box open though, until I figure out how to turn the neck joint into a bolt-on mortise and tenon. Bruce W.
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phavriluk
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Re: Yamaki 331s top replacement?

Post by phavriluk »

I suggest a visit to 'Luthier's Cool Tools', a side offering from Dave Micheletti, and there's photos of his bolt-on neck installation package which is very well supported by his documentation. I've used my take on Dave's process on a half-dozen of my guitars (all of them, truth be known) and I've been very satisfied, especially during the headscratching first applications. He took a lot of the mystery out of attaching necks.
peter havriluk
Stray Feathers
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Re: Yamaki 331s top replacement?

Post by Stray Feathers »

Thanks for the link Peter - it's an interesting idea. I'll look into it more carefully, but there are some concerns with the guitar. The truss rod is massive, just shy of 1/2" wide, for example, but it still might work. There is also the cost to get one to Canada. Is the guitar worth it? Well, I've already justified money and time because it has been "in the family" for fifty years, so maybe. At this point, I have been thinking about making a mahogany spline that is sort of T-shaped, with the narrower side, say 3/8", fitted snugly and glued into a groove in the neck heel (which is quite slim), and the other side of the spline being 5/8" or 3/4", to go in a groove in the neck block, as would happen normally, and fittings (I use bolts and barrel nuts) drilled through the spline. One concern is that the neck block grain is vertical and to avoid splitting it, I think I will laminate a cross-grain or plywood piece on the inside. Bruce W.
Stray Feathers
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Re: Yamaki 331s top replacement?

Post by Stray Feathers »

A little more progress on this job between tasks on a new build. I cleaned up the neck and body faces to get ready for refitting the neck as a bolt-on mortise and tenon neck. I clamped the neck in a vise along with the jig I made early on for routing neck mortises in the body. I routed a 1/2" mortise, 1/2" deep, in the end of the neck in several passes, which was uneventful. Then I used a scrap of mahogany (ironically a scrap from a neck block I cut out of an early build because I glued it in crooked . . . waste not, want not). I cut a 1/2" x 1/2" tenon on this piece, and trimmed one end of the tenon to fit in the mortise. Using the centre of the tenon as a centre line, I cut the block to 3/4" wide (just over) to go into the body mortise when I cut it. There was a fair bit of finessing to get a good fit, then I glued the transition piece to the neck with epoxy. The neck block in the guitar (see photos in Dec. 9 post) is shallow, with the grain running vertically, so I fitted and glued a piece of mahogany about 3/16" thick with grain running perpendicular to the existing block, to strengthen it. I also noticed that the original block was cut crooked, which you can see in the photo. Maybe a Friday guitar . . . but I'm not going to do anything about that. When the epoxy cures, I'll cut the body mortise as I usually do. I'll have to do some cutting to get the truss rod back in. Once I am sure it will work, I'll glue the new top on and figure out bindings. Bruce W.
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phavriluk
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Re: Yamaki 331s top replacement?

Post by phavriluk »

Floating tenon - - - wonderful. And the heel will never break!
peter havriluk
Stray Feathers
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Re: Yamaki 331s top replacement?

Post by Stray Feathers »

Well, it didn't occur to me it could be called a floating tenon, so I learned something. And thanks for your confidence in the strength of the joint - I was trying to imagine what it would take for strings to pull it apart!
Stray Feathers
Posts: 700
Joined: Sun Sep 08, 2013 11:39 pm
Location: Ladysmith, BC

Re: Yamaki 331s top replacement?

Post by Stray Feathers »

I cut the mortise in the head block today - had to widen it to centre the neck when I discovered the original head block was not centred! I drilled the modified neck and the head block for hardware and made sure I could align the neck and do a proper setup when the time came, and then glued the new top on. Feels like moving forward for a change after backtracking. Bruce W.
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Stray Feathers
Posts: 700
Joined: Sun Sep 08, 2013 11:39 pm
Location: Ladysmith, BC

Re: Yamaki 331s top replacement?

Post by Stray Feathers »

The bindings are done, maple with bwbw purflings, and an inner bwb purfling on the top only. I only replaced the top on this guitar, but you can see in one photo how the new top binding contrasts with the original thin plastic binding on the back, so I replaced both bindings. The back and sides are thin mahogany veneer so I will have to be careful with finish scraping and sanding, and scuffing before putting new finish on. Bruce W.
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