How to make a compound radius?

rauchman

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I'm in freefall down the rabbit hole of my next build. In this thread about body blanks, I'm getting a body blank and plan on doing full routing of the blank. With me doing the routing, it frees me from existing constraints with Fender spec'ed necks.

This has me now leading to making my own neck. Still trying to wrap my head around the possibilities....
  • Number of frets
  • Scale
  • Inlays
  • Bindings

I've been watching numerous vids, but haven't seen anything that shows....how to make a compound radius for the fretboard. Any recommendations on how to do this?
 
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Back in the day warmoth used a funky jig composed of a belt sander and a funky two-arm pendulum that held the neck. The neck would rock back and forth across the belt sander making the radius. The difference for compound radius was the length of the pendulum arms at the heel and nut, which were different lengths to match the different radiuses you wanted at each end. Naturally you'd have to change the axis of the pendulum to make it sit flat on the belt sander: the heel pivot point would be further away.

There's a photo of the old warmoth jig out there, but I can't find it just now.
 
Back in the day warmoth used a funky jig composed of a belt sander and a funky two-arm pendulum that held the neck. The neck would rock back and forth across the belt sander making the radius. The difference for compound radius was the length of the pendulum arms at the heel and nut, which were different lengths to match the different radiuses you wanted at each end. Naturally you'd have to change the axis of the pendulum to make it sit flat on the belt sander: the heel pivot point would be further away.

There's a photo of the old warmoth jig out there, but I can't find it just now.

Yep, without a CNC at your disposal this is the way.

What Warmoth used to use was more than just a jig. It was a fairly complex machine with two rocking arms that could be independently adjusted to what the radius at each end of the neck was supposed to be. Once each arm was set and the neck was attached between the arms the whole contraption rocked across a belt sander, thus creating a perfectly tapering compound radios along the length of the fretboard.

This kind of thing is what Ken and his father Jim excelled at. They created many such machines in the early days of Warmoth.

I'll see if I can find a pic in the Warmoth archives....
 
Maybe a set of fell draw shave knives with appropriate varied curvatures?
 
It might be a bit pricy just to do one neck.

 
This is going to sound like a crazy question, but I've always associated the compound neck with warmoth, did they invent it?
 
This is going to sound like a crazy question, but I've always associated the compound neck with warmoth, did they invent it?

Yes. We were the first to do it, and our process was invented by us.

I believe Jackson was working on it at about the same time, and I have seen them claim to have invented it also, so it's likely a case of parallel development.

Regardless, Warmoth was definitely at the forefront.
 
Cool, I did not know. I just checked the about us page. Only two words! On Compound necks .
 
Another way to do this would be to build a router jig that can be adjusted for different radii at each end, and then use a router with a number of length wise passes to create the progressive radius.
 
I have no experience with this jig but I see it popping up in my research for something to carve the other side. (For a very shortscale all cutaway set neck)

If you're this far down the rabbit hole might as well let go of that first rope and descend further.

 
I have no experience with this jig but I see it popping up in my research for something to carve the other side. (For a very shortscale all cutaway set neck)

If you're this far down the rabbit hole might as well let go of that first rope and descend further.


Thanks for that......as I fall deeper in the rabbit hole
 
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