Harmony Bobkat gets a Tune-O-Matic bridge, clean up, and a setup

My friend’s guitar that I worked on over two months ago. I just didn’t have the time to write about it in detail until now.

It seems like it sat in someone’s closet for a while after someone made an interesting modification to it – the neck was glued to the neck pocket. Also there was glue all over the body of the guitar under the pickguard. I forgot to take “before” pictures, but basically, the neck had one very small point of contact with the neck pocket, and the screws were still used to hold it in place. If the screws weren’t used, the neck would have snapped out under string tension. No doubt about it.

I saw that the point of contact was tiny, so I decided to just dislodge the neck out. That’s dumb. Don’t do it. Use steam or heat or how water. This is what it looked like when I did that:

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Not horrible, but it could have been cleaner maybe. Also, this is a testament to the bad gluing job.

I pulled out that big splinter and glued it back to the neck. It was a weird fit. Actually taller than the neck.

 

I shaved it down with a chisel so that it’ll be flush with the neck.

Next I cleaned up the neck pocket and body of the guitar from all the glue. I wish I took pictures after it was done because as you can see from the first picture in this post, there was a lot of glue.

 

The next step was installing a Tune-O-Matic. That was a bit of a big deal for me because I’ve never done it before and it’s also kind of a big modification to the guitar, but it turned out well and made the guitar more playable.

My friend wanted a Kalamazoo style TOM installed. These are the ones with the “skinny” posts and require less precision to install. However, I saw that StewMac makes a fancy and expensive tool for installing these, so I thought I’ll make one myself. It took some drilling tapping, and playing around with it, but the result turned out ok (at first).

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My tool in action.

I set to get the posts 3/4 of the way in, and the tool worked well at first, but as the posts were getting deeper, the tool ended up turning in place instead of pushing the post further into the guitar. At some point I mangled one post and realize that I what I’m doing isn’t working. I googled around a bit and found a really simple and cheap solution. I can’t find the links, but here’s the gist of it:

The posts have 6-32 thread count/size. Get a a 6-32 nut and the appropriate nut driver. Now take the thumbwheel and thread it on the post. Now take the nut and thread it against the thumbwheel (coming from the “top” side of the post). Tighten the two against each other real hard. Like, really hard. Now you use the nut driver to drive the post into the guitar. Super easy and simple, and would have saved me a lot of time and trouble. Seriously, I don’t know why anyone would use the StewMac tool, which admittedly is nice but very expensive.

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All good!

Next was grounding the guitar. The original bridge was made of wood, so no one thought to ground the guitar. What it meant was that the strings and the hardware were at one potential that was different from ground (0V). Things weren’t going to be any different with the TOM installed because it too has no path to ground. One solution is to drill through the body cavity into where the posts go. That was going to take a lot of precision and a special drill bit. Instead I opted for something much simpler. I used copper tape to make a path between the treble side TOM post and one pickguard screw hole.

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Then I wired a little ring to the electrical ground.

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The following electrical path is formed: bridge -> copper tape -> pickguard screw -> electrical ground (via the ring and wire). Now the guitar is grounded! Here’s what it looks like with the pickguard on. The only thing to keep in mind is to not over-tighten the one screws that holds the ring in place or the pickguard will break.

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You can barely tell it’s there!

Lastly, what was left was to set it up. My friend uses 52 strings and tunes down to C, and course, I compensated for that + intonation before drilling the holes for the TOM posts. Anyway, the neck had a bit of a backbow because the wasn’t a lot of string tension on it. It’s also possible that not being glued in changed something, but I doubt it. So I was set to adjust the truss rod, but couldn’t get nut driver in there. The nut looked like it’s 1/4″ but it won’t turn. I tried 5/16″ driver following the suggestion of a friend, but that didn’t work either. After further inspection, I realized that I can’t really fit the driver in the little “bed” under the nut. So I pulled out my tiny chisels and excavated a little bit of wood from that area so I can fit the tool in there.

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Very small amount of material removed.

Now that I was able to fit the tool in, the nut wouldn’t budge. I know better than to force it, so I talked to a friend who’s the most knowledgeable person I know when it comes to guitars. He said that there’s a good chance the rod is broken, and if not – it could break easily. He admitted to breaking one before and said that 50% of Bobkats he saw had a broken truss rod. He didn’t have any tips for undoing the nut, but I appreciated him telling me that these truss rods are fragile.

I squirted a tiny bit of WD-40 on the nut and rod and let it sit for maybe 10 minutes. Then when I came to adjust the nut, it turned without having to apply force to it. Great! So yeah, if you have a truss rod nut that’s seized, give it a squirt of WD-40.

I loosened the rod and the guitar played really well.

These guitar are made horribly, but the pickups sound absolutely fantastic. Really made me want to get a couple of goldfoils.

Here are some pictures of the guitar. Other than the ridiculous gluing mod, it was in a decent condition.

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