slor Posted August 5, 2007 Report Share Posted August 5, 2007 I'm working on an early 70s Guild Starfire bass. The neck has separated from the body, which doesn't seem like too big of a deal, but some questionable "work" was done to try and rectify the situation. Looks like someone drilled a good 1/2" hole through the heel and crammed a dowel through the dovetail and into the body. To add insult to injury, they then screwed a large woodscrew through the dowel as well! I've cleaned out the neck pocket, and am now wondering what the best way to reconstruct the dovetail is. Keep in mind I have little access to power tools, and not a huge amount of experience with this issue! Thanks much, Seth Quote Link to comment Share on other sites More sharing options...
jammy Posted August 5, 2007 Report Share Posted August 5, 2007 My first thought is to totally remove the old dovetail section from the neck. and clean everything up. Then make a new dovetail section (oversize), glued and doweled into place on the neck Then re-fit to the pocket, which seems to be in good condition! Quote Link to comment Share on other sites More sharing options...
Prostheta Posted August 5, 2007 Report Share Posted August 5, 2007 (edited) Agreed - the dovetail tenon is a mess. A LOT of attention should be devoted to the cleanup however as you'll be dealing with a lot of endgrain, and good strong glueing between these sections is a must. The new tenon could possibly by recessed slightly into the heel to provide more security along with dowelling, but this will be a lot of awkward work. You have room to use a longer tenon under the fingerboard, so I would consider lengthening it a bit myself. It also looks like there was wood splinted into the pocket to make it a dovetail....I would take that out and make it into a wider straight "Gibson style" tenon. A perfect world solution would be to remove the fingerboard rout and splint a piece of wood into the top of the neck, extended out to be a long tenon. This would of course involve refinishing and headaches with the existing fretwork. Opinions? Edited August 5, 2007 by Prostheta Quote Link to comment Share on other sites More sharing options...
slor Posted August 6, 2007 Author Report Share Posted August 6, 2007 Thanks much guys, this makes good sense. I thought the dovetail arrangement in the pocket looked unusual but don't know enough about them to know how they're "supposed" to be constructed. Yes, good cleanup seems important. I'm guessing the rubbery yellow glue traces on the bottom of the fingerboard is old wood glue, I heated it pretty well but it's tenacious. Finally, any tips on doweling the new tenon into place? Seems like it should be: Drill into the new tenon and the heel to accept the dowel (notched to allow excess glue to escape). Wood or hide glue the dowel into the tenon, then glue the tenon assembly into the heel. I'm guessing I'll want the new tenon to be a fairly snug fit in the pocket, but loose enough to accept glue without starving the joint. Sound right? Thanks again, Seth Quote Link to comment Share on other sites More sharing options...
Prostheta Posted August 6, 2007 Report Share Posted August 6, 2007 It looks like a very short tenon to be honest - more like a bolt-on acoustic, but without the bolt! It would be feasible in that respect to enlarge the mortice and get rid of those (what look like) two pieces of wood stuck in there and drop the mortice back 1" towards the neck pickup cavity. You can make the tenon longer and more secure in that respect. The weakest point will be the tenon and the neck as it's an endgrain join, and a dowel will only help marginally IMO. I view dowels as being better for locating and helping make a better glueing joint as opposed to for their mechanical strength (which they do provide but not as much as a good clean join anyway!). Am I right in thinking that a dowel was located from the neck pickup cavity down into the tenon? It wasn't such a bad idea as it might seem, as the relatively small tenon looks like a bit of a weak design to me. Given the size (or lack of!) of the tenon, i'm surprised that the fingerboard hasn't started to seperate from the neck....the pressure seems as though it would have been applied where the fingerboard joins the neck....I would definitely be tempted to get the fingerboard removed and rout a tenon a 2"-3" deeper into the neck, and 1" deeper into the body. This is one of Ant Setchell's tenon pics: If you imagine that the tenon is a seperate piece, but extended into the neckan inch or two, that is your ideal world target but it depends on whether removing the fingerboard is more hassle than you're willing to put up with :-/ Best of luck - I hope whichever repair option you choose works. Any more pics of the bass? Quote Link to comment Share on other sites More sharing options...
jeffhigh Posted August 6, 2007 Report Share Posted August 6, 2007 Whilst a bigger tenon is a very good thing, and I would certainly go that way, if you dowel it to the existing neck, there will be a weak point right where it has failed before. I would be inclined to cut away the base of the heel parallel to the fingerboard for about half the depth of the heel then glue on a new piece of mahogany to form the heel and tenon. This will probably look better than patching the dowel hole and will certainly be stronger Quote Link to comment Share on other sites More sharing options...
slor Posted August 6, 2007 Author Report Share Posted August 6, 2007 Interesting...interesting. Prostheta: Good call on the fingerboard. Yes it has started to separate from the heel, only about an inch or so, I was going to use gap-filling CA and leave it at that. And no, the dowel was drilled in from the outside of the heel down into the pocket. Jeffhigh: I hadn't thought of such a radical step, though it makes sense to me. Only issue with both your guys' suggestions is that I have limited shop space and tools (hand planer, bench sander, Dremel plunge router), and more to the point limited skills. I can get my head around replacing the existing tenon, but I'm hesitant to go further. I would like to take the heel back further towards the pickup cavity, but I wouldn't even know where to start. Sawing the "cut lines" and then gradually plunge-routing the middle out? Chiseling? Thanks again you guys, this is really helping! -Seth Quote Link to comment Share on other sites More sharing options...
Prostheta Posted August 6, 2007 Report Share Posted August 6, 2007 I would rout the pocket out. I think that no matter how far you recess the tenon into the body however, it will be the quality of the tenon joining to the neck as it's a pain of a place to work from. I would be hesitant to use a saw to remove wood as they can wander easily. I think that you might be better off enlisting the help of an experienced local luthier who can set a tenon deeper into the neck (under the fretboard I would have thought) and make sure it isn't altering the geometry of your instrument either. For what it's worth, I would consider that (if the instrument has significant personal or monetary value also!) to make sure the job is done perfectly. Quote Link to comment Share on other sites More sharing options...
jeffhigh Posted August 6, 2007 Report Share Posted August 6, 2007 What you have to be careful of is doing a cosmetic restoration of the tenon which ends up weaker than the original. The critical area for resisting the pull of the strings and impact is the back of the neck heel where the tenon has failed and if you dowel it the crossection of the dowel is likely to be less than half the original Tenon If you do not have the skills and tools to make a really strong repair using wood, perhaps you are better off using the existing hole and a bigger and longer wood screw to hold it Whilst not a professional repair it is reversible and you already have a hole there Quote Link to comment Share on other sites More sharing options...
slor Posted August 6, 2007 Author Report Share Posted August 6, 2007 Hmm. Here's the story: Since early this year my job has been as the tech at a small guitar shop; I've been messing with electric guitars for 25 years or so, but only recently getting into more serious repairs. I think this job is within my skill level--within limits. Sawing off half the heel, or removing the fingerboard, I could do, but they'd be a stretch. Carefully gluing a new tenon into place, and deepening the pocket, I think I can do. (I do have a friend I can call on for help with the routing operation.) The bass was offered to me by a guitar dealer I know; he knew I liked Guild basses (I already have one) and my idea is to sell it when done. So no, there's no personal attachement to the instrument, but it's got to look good and play well (and be structurally sound) if I want anyone to buy it! -Seth Quote Link to comment Share on other sites More sharing options...
Prostheta Posted August 6, 2007 Report Share Posted August 6, 2007 I don't think anyone would buy it broken or half repaired, so it might have to be a case of writing it off or plain taking the plunge (no pun intended) and removing the fingerboard to rout in a new tenon. This is what I would propose - take off the fingerboard and.... Apologies for the weird choice of pic to demonstrate on....I couldn't immediately find anything with no fingerboard or a tenon! Quote Link to comment Share on other sites More sharing options...
jeffhigh Posted August 7, 2007 Report Share Posted August 7, 2007 If you are reallygood with a chisel (or very slow and careful)you could cut a pocket for the new tenon from the existing face of the heel. Just drill out the bulk of the material then trim to size. BTW use a stronger wood than mahogany for the tenon (hard Maple?) Prostheta's sketch for the enlarged tenon looks like a good idea to me as long as the neck block does extend all the way to the pickup hole Quote Link to comment Share on other sites More sharing options...
Prostheta Posted August 7, 2007 Report Share Posted August 7, 2007 The fingerboard stops short of the cavity, so the tenon will show unless the pickup and mounting ring covers it. I guess it would be possible to use a forstner bit to cut two 1" dowels into the neck block, and if the existing dovetail in the body is chiselled square and filled with new wood then two corresponding round sockets could be recessed into the body. I'm not sure how strong this would be, but it would be one of the easier ways to cut and recess into the neck. Do we know where the truss rod ends? Personally I think this is more difficult as the dowels would be a PITA to align. Quote Link to comment Share on other sites More sharing options...
slor Posted August 7, 2007 Author Report Share Posted August 7, 2007 Wow, 3D diagrams and everything! Most impressive.... Personally, I think Prostheta's earlier idea is the best given my skill level: I know how to pull a fingerboard, and with a little guidance can rout out the neck pocket to accept a longer tenon. I just remembered seeing an older Guild Starfire (an early single-pickup model with the p/u further back towards the bridge). The neck had been replaced completely, suggesting Guild had issues with this arrangement. I have a similar-vintage Starfire guitar, which fortunately shows no signs of failure! Many thanks again gents! -Seth Quote Link to comment Share on other sites More sharing options...
Prostheta Posted August 7, 2007 Report Share Posted August 7, 2007 I'm not surprised they saw failures in the field....the tenon is shallower than any Gibson have made, the only saving grace is that it was a dovetail really....I think the dowelling that was done wasn't the *worst* repair choice by far....does the dowel or screwhole emerge on the outside of the heel, or is it limited to being just inside the neck pickup cavity? Quote Link to comment Share on other sites More sharing options...
slor Posted August 7, 2007 Author Report Share Posted August 7, 2007 No, it enters from the heel and doesn't make it too far into the body, I'm guessing. Certainly not as far as the pickup rout. Quote Link to comment Share on other sites More sharing options...
ToneMonkey Posted August 9, 2007 Report Share Posted August 9, 2007 Just to throw something else into the mix (and I have no experience in this type of repair), but I'd explore the possability of cleaning up that dovetail pocket and replacing the existing male part to fit straight in. I'd have a look at bringing something from the neck pup pocket that will pull the neck towards it when it's tightened up. Like those funky bolts that are used in cabinet making. Like I said though, I have no experience in this sort of thing (well not on guitars), so I just thought I'd throw it in there. Quote Link to comment Share on other sites More sharing options...
Prostheta Posted August 9, 2007 Report Share Posted August 9, 2007 You can't just replace the existing tenon as it has nothing good to secure it to on the neck - just endgrain and the underneath of the fingerboard. The tenon needs to extend back into the body of the neck or else the neck will just pop off, leaving a nice chunk of wood securely glued into the newly cleaned dovetail! Quote Link to comment Share on other sites More sharing options...
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