The thing I've been worried about the most in my build is cutting a curved truss rod channel. I've considered using a dual action rod which is much easier to install but I wanted to have a go at a carving the channel for a vintage rod. Keep in mind there are folks on here who have used a vintage truss rod with straight channels with success.
I got the idea for the jig from this thread on TGP:
Calling Out to Builders…Favorite Jigs, Templates, Tips & Techniques - Page 5 - The Gear Page
Our own Roman Rist and Jack Briggs participated in the thread. The thread is full of all kinds of great tips and examples of jigs. I modeled my jig off pic Scott Lentz posted about halfway down page five. Thanks to Scott for the pics.
Also Roman gave me the idea about bowing the truss rod to trace the template in an older thread about this very subject. Thanks to Roman and also BCR Greg who have given tips along the way.
So here's the jig:
The construction is simple. You need a planed board about 30" long, 8-10" wide, and about 3/4" thick. I found some poplar at my local hardwoods store that fit the bill nicely. You mark where a few frets are for reference points. Then you take your truss rod and bend it a bit while you trace the shape of the bent rod into one side of the wood.
To shape the curve of the rod into the board you could use a band saw but I chose to use my oscillating spindle sander. It took me about ten minutes to rough out the curve with the spindle sander. I then finished it off sanding by hand.
The other piece of wood you need is something to mount the hold-down clamps. In this case I found some scrap maple at the wood store. It's perfect for the job. I got the clamps for five bucks each from Harbor Freight. I'm not a fan of Harbor Freight but for things like the clamps it's good. I screwed the maple onto the poplar like this:
I put the neck on the jig and used it to help place the clamps. I made it so the clamps touch the neck on parts that will eventually be cut away. I screwed the clamps into the maple and the jig was done.
Here's a good top view where you can see the curve in the board in relation to the neck:
One of the biggest pains of this project was finding an arbor long enough to mount a 3/16" slot cutter at the proper height. Most arbors are 3" long which isn't long enough. While I was at the tool store I eyeballed a router bit that was a little over four inches long and had room for two cutters separated by a bunch of spacers. I think these types of bits are used on moldings or something like that. I asked the salesperson the price of the bit and he told me it ran around $160. Yeeeech. It turns out I was able to buy the just the arbor and a bunch of spacers for around $30.
I bought a 3/16" slot cutter with the arbor and used the 7/8" bearing that came with it for the new arbor. When I set up the new arbor I found I didn't have enough spacers to reach the threads at the top of the arbor. Without more spacers there would be no way to tighten the locking nut of the cutter. I ended up buying another 7/8" bearing as a cheap way to add another spacer. Here's what the cutter looked like when I finished putting it together:
Here's how the whole thing works. The 3/16" slot cutter/arbor is mounted in the router table. The bearings follow along the edge of the jig that has the curve of the rod. As I get into the middle of the jig the curve of the jig gets deeper. At it's deepest point this setup should cut a channel of 1/2". I can manipulate the depth a bit by pulling the neck closer to the edge of the jig or pusing it back. you set the height of the cutter so that it hits the centerline of the neck.
I did some preliminary testing today on some scrap before I had to go do Christmas eve stuff. It cut the channel great but burned the wood a bit in the process. I'll fine tune the speed of the router to get rid of the burning. Another slight problem is that I either didn't get the clamps tight enough or I need another clamp because the test piece drifted backwards a tad. This is a minor problem that I'll get fixed in the next day or two. Oh the 3/16" slot cutter didn't cut the channel wide enough. I can either buy a 1/4" slot cutter or I can widen the channel a bit by cutting the center and then raising the router bit a little and cutting again. Of course you would then need to take the same amount off the bottom of the channel.
That's it. I hope this helps anyone who is struggling with the mystery of the curved truss rod channel. Feel free to ask any questions that you have.
I got the idea for the jig from this thread on TGP:
Calling Out to Builders…Favorite Jigs, Templates, Tips & Techniques - Page 5 - The Gear Page
Our own Roman Rist and Jack Briggs participated in the thread. The thread is full of all kinds of great tips and examples of jigs. I modeled my jig off pic Scott Lentz posted about halfway down page five. Thanks to Scott for the pics.
Also Roman gave me the idea about bowing the truss rod to trace the template in an older thread about this very subject. Thanks to Roman and also BCR Greg who have given tips along the way.
So here's the jig:
The construction is simple. You need a planed board about 30" long, 8-10" wide, and about 3/4" thick. I found some poplar at my local hardwoods store that fit the bill nicely. You mark where a few frets are for reference points. Then you take your truss rod and bend it a bit while you trace the shape of the bent rod into one side of the wood.
To shape the curve of the rod into the board you could use a band saw but I chose to use my oscillating spindle sander. It took me about ten minutes to rough out the curve with the spindle sander. I then finished it off sanding by hand.
The other piece of wood you need is something to mount the hold-down clamps. In this case I found some scrap maple at the wood store. It's perfect for the job. I got the clamps for five bucks each from Harbor Freight. I'm not a fan of Harbor Freight but for things like the clamps it's good. I screwed the maple onto the poplar like this:
I put the neck on the jig and used it to help place the clamps. I made it so the clamps touch the neck on parts that will eventually be cut away. I screwed the clamps into the maple and the jig was done.
Here's a good top view where you can see the curve in the board in relation to the neck:
One of the biggest pains of this project was finding an arbor long enough to mount a 3/16" slot cutter at the proper height. Most arbors are 3" long which isn't long enough. While I was at the tool store I eyeballed a router bit that was a little over four inches long and had room for two cutters separated by a bunch of spacers. I think these types of bits are used on moldings or something like that. I asked the salesperson the price of the bit and he told me it ran around $160. Yeeeech. It turns out I was able to buy the just the arbor and a bunch of spacers for around $30.
I bought a 3/16" slot cutter with the arbor and used the 7/8" bearing that came with it for the new arbor. When I set up the new arbor I found I didn't have enough spacers to reach the threads at the top of the arbor. Without more spacers there would be no way to tighten the locking nut of the cutter. I ended up buying another 7/8" bearing as a cheap way to add another spacer. Here's what the cutter looked like when I finished putting it together:
Here's how the whole thing works. The 3/16" slot cutter/arbor is mounted in the router table. The bearings follow along the edge of the jig that has the curve of the rod. As I get into the middle of the jig the curve of the jig gets deeper. At it's deepest point this setup should cut a channel of 1/2". I can manipulate the depth a bit by pulling the neck closer to the edge of the jig or pusing it back. you set the height of the cutter so that it hits the centerline of the neck.
I did some preliminary testing today on some scrap before I had to go do Christmas eve stuff. It cut the channel great but burned the wood a bit in the process. I'll fine tune the speed of the router to get rid of the burning. Another slight problem is that I either didn't get the clamps tight enough or I need another clamp because the test piece drifted backwards a tad. This is a minor problem that I'll get fixed in the next day or two. Oh the 3/16" slot cutter didn't cut the channel wide enough. I can either buy a 1/4" slot cutter or I can widen the channel a bit by cutting the center and then raising the router bit a little and cutting again. Of course you would then need to take the same amount off the bottom of the channel.
That's it. I hope this helps anyone who is struggling with the mystery of the curved truss rod channel. Feel free to ask any questions that you have.
