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Enjoying a quiet night at home with my better (far better) half for New Year’s Eve, and taking a few minutes to plan out my next guitar build. I’ve built a few different types of bolt-on necks that turned out well, and recently a few dovetails that turned out great. Next I want to try out a Gilet/Gore bolt on bolt off neck joint. I think I’ve gathered all the bits I need, including a hollow chisel mortiser (got a deal on a used one). If anyone with relevant experience would like to share any tips, that would be much appreciated. Thanks, and Happy New Year!

In terms of the bolt bar, nominal 3/8” brass bar fits easier in the mortise from a metric 10mm hollow chisel vs the more commonly found 3/8” hollow chisel. Either works but with the latter you will spend more time filing the bar down to fit the mortise. This is for standard brass bar stock - if you choose to use aluminium or steel (titanium?) square bar you may find stock that is a much closer fit to the mortise your machine cuts.

Thanks, Josh. I tested this out a few days ago and noticed that my brass bar stock was too snug in the 3/8” hole. I’ll look into getting a 10mm chisel/bit set. I actually ordered a 7/16” set after I saw that the 3/8” hole was too snug, but 10mm will likely be a closer fit to what I need.

Unless you really want a metric set of morticing chisels you could use a slip of veneer to pack in the mortise if you find it is a bit wide using the 7/16th chisel.
It is a bit fiddley, but you can enlarge the mortise using the 1/2 inch chisel by moving the work piece over a "fuzz" . or by filing the mortise rather than filing the bar stock.

Thanks, Clay. Yeah, I thought about ways of either making the 3/8" square hole a bit larger or a 7/16" square hole a bit smaller. I can fashion a sanding stick easily enough to open up the 3/8" hole, and I keep a lot of veneers around that would be handy for tightening up a 7/16" hole. Also, I was able to find a single 10mm chisel/bit set for pretty cheap on eBay; it was cheap enough to justify experimenting with it. We'll see what the quality is like. I would like to avoid making the 3/8" brass bar smaller. Once it is drilled and tapped for a 1/4-20 bolt, the walls around the holes will be thin enough.

For the fretboard extension support, I bought some short barrel T-nuts. The barrel length on "standard issue" T-nuts looked a bit long to me for this particular task.

For the bolt hole drilling jig, I'm varying a bit from the book. I have 5/16" drill bushings that I will install in a wooden "fake tenon" rather than making the whole "fake tenon" out of steel. I like to minimize metal work (because I'm not great at it).

As always, any suggestions are greatly appreciated.

Don, staying with the bolt bar. I found here in the UK that a 3 eights bar did fit. It is very snug but it does go in OK, maybe just lucky with the tolerances on my morticer.

However since one ends up taking it out and reinserting a few times I ended up drilling a short hole in the end of the brass bar into which a wood screw can be jammed to help in removal. (Can't lay my hands on a pic just now)

The other somewhat more important thing is that when using the drilling jig for the bolt holes into the heel, G&G turn the jig round to do the holes in the neck and the head block. Well if you have any inaccuracy in the allignment of the holes, and this is likely in an amateur shop then this error will be doubled leading to probable misallignment of the holes. So I turn the steel block round through 180 degrees so any missalignment is the same for both parts and the bolts fit fine.

I haven't tried the full BOBO joint yet, it seems to get pretty complicated. Best of luck!


Dave

Thanks, Dave. I think I had seen a photo on the Australia/New Zealand forum regarding the idea of a screw in the end of the bolt bar, and that stuck with me, so I was definitely going to drill and thread the end for some sort of smaller bolt. It feels essential to be able to take the bolt bar out a few times. Good suggestion.

Also a good suggestion on how to deal with the bolt hole drilling jig! I'll need to make sure to unscrew and flip the "fake tenon" around when drilling the holes in the neck tenon. I now see the opportunity for mischief if I don't. I appreciate it!

Yeah, the BOBO joint has a lot going on, but in my view, it is the best version of a "no glue" neck joint, so I wanted to try one out for myself. Experience is the best teacher.