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Hi, folks-
"Ship in a bottle department":
Nothing revolutionary here, but perhaps this will be of interest to somebody.
I'd wanted to try a bolt-on neck on an archtop, and since my current 'learning project' is a junker plywood archtop, I figured some details for a method to use. The basic idea has been described online by Jay Harland and others- you need a long allen wrench so that you can work through the endpin hole to tighten the bolts.
Wrench- Get a section of allen key welded on to the end of a steel rod, and add a T-handle while you are at it. (Friendly neighbor with a MIG welder did this in a few minutes- I built a quick (wood) V-block-type jig to hold the two parts in line for welding.)
Add a couple of rare-earth magnets (LeeValley) near the end of the allen key and fix in place with CA glue.
I'd planned on putting a jack-type endpin in this guitar, so had a 1/2" hole to work through. It makes things easier to have a larger hole- if I were adding a regular endpin, I'd probably plug the hole and re-drill.
Drill- If I'd been thinking ahead, I'd have had my friend weld a 1/4" drill on the end of another rod. However, a few minutes with a rod and the grinder provides a serviceable spoon-type drill, so that I could drill the pilot holes for the threaded inserts in the neck through the bolt holes I'd drilled in the neck block. I found this works better for me than marking the holes through the guitar (pointed rod or similar) and drilling the neck holes separately- though that's how I've done my guitars with 'standard' soundholes.
You need to improvise a way to 'feed' the bolt on to the end of the allen wrench, using the F-hole. Something in the 'coat hanger and chewing gum' department works for me here.
It's useful to have a magnetic pickup wand available to retrieve dropped bolts, etc from the inside of the guitar.


It's a handy technique and saved me a lot of time messing with re-fitting the dovetail on this old guitar- when I finished separating the neck from the body, a whole pile of misc. shims (wood, cardboard) came away with the gobs of softened glue. There was 1/4" of space around the dovetail for 'adjusting' with shims- they don't make 'em that way any more!

Cheers

John

John...I just completed my first bolt-on in much the same way. I just end-drilled a rod & JBWelded a section of allen wrench in. (the bolt stays on the wrench fine 'till you feed it into the headblock hole)

I talked to Mark Blanchard & got some great ideas from him. I elected to fit & align the neck perfectly first, THEN drill (1/4"x24" long), via endpin hole, through the headblock & into the tenon, thereby assuring the angles and alignment are bang on. Remove the tenon, insert a "drill bushing jig" into the hole(s) to ensure the lateral "barrel bolt" holes are in alignment & drill these. Everything worked out beautifully.

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Dave
Milton, ON

Good tips, Dave.
I absolutely agree with the idea of drilling the neck holes with a long drill via the endpin hole.
I put two bolts in this project guitar- the first I did by marking the neck hole with a long rod/center punch via the endpin hole, then drilling. I had lots of trouble with cross-threading- you can't 'feel' what you are doing when inserting the bolt with a 2 ft long wrench, compared to threading it in by hand through the soundhole.
The second hole was drilled with the long drill and worked like a charm. Threaded inserts are not as forgiving as barrel bolts, so good alignment is even more of an issue when using them.

Cheers

John

Yeah, I never felt comfortable with inserts - long discussions about the right "type" and it seems so easy to screw it up. Plus, I never felt insert threads had the mechanical advantage of a barrel. Two "bonuses" are that the barrel is kind of self aligning, both sideways & in pitch and that you can install the screw in the tenon/ ensure ok alignment/ remove screw & install neck (& be confident it will screw right in perfectly).

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Dave
Milton, ON

(........plus, you've taken the time to get headblock & tenon holes in perfect alignment, then go ahead & possibly alter the insert axis during installation!).

Another consideration is that the neck could be repositioned at some point, the tenon screw holes enlarged a bit the barrel would realign & still work fine!

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Dave
Milton, ON