MIMF

I thought I'd post up some pictures of my Fretboard shaping jig. I generally use Mulga or Gidgee for my fretboards. Both are very hard, fine grained timbers that finish beautifully but if you have ever had to use a sanding beam to get the shape you know how time consuming that is!

I didn't invent this concept but I love it so much I had to share it.

The jig was made mainly with scrap from around the workshop with a couple of pieces of PVC pipe and the Aluminium side supports costing about $10 from the hardware.





This is the set up for the 12 inch radius



And if I want to do a 10" radius I just have to make a new box with the 10" radius on the bottom and raise one of the risers.

Nice jig Martin.
Just by the way, in your diagrams, the router bit protrudes below the radius guide, so you will get a radius tighter by however far it protrudes: e.g. if it protrudes 1/4" below, and you use a 10" guides, you will get a 9-3/4" radius on the board. You probably realise this, but I thought it worth mentioning.

Well spotted Greg. The drawing isn't that accurate and my router bit is closer to the curve. If I make any more boxes, I'll certainly allow for the router bit depth. Thanks

This is so cool! AND one of the best parts about this page. The sharing of neat ideas. I only build flat fingerboards, but I want to build one of these.

Hi Martin,
I love the simplicity of the design. And I think I have enough "scroungings" to put one together for free. Thanks for showing this.

I have been doing my fingerboards that way for quite some time now. I saw the design a long time ago when someone posted it here, I'm surprised you didn't see it then Clay! You've been around here for years too!

so are the pvc pipes attached or just loose between the angle aluminum and the wood strip so they roll as you move the jig?

John Sonksen wrote:so are the pvc pipes attached or just loose between the angle aluminum and the wood strip so they roll as you move the jig?

Hi John,

The PVC pipes are screwed in place into the timber base and also bolted to the aluminium strips. The wood strips help hold the pvc too. I found that the pvc needs to be as stable as possible. The radiused box slides on the PVC really well.

Martin Taylor wrote:

John Sonksen wrote:so are the pvc pipes attached or just loose between the angle aluminum and the wood strip so they roll as you move the jig?

Hi John,

The PVC pipes are screwed in place into the timber base and also bolted to the aluminium strips. The wood strips help hold the pvc too. I found that the pvc needs to be as stable as possible. The radiused box slides on the PVC really well.

Okay that makes more sense. I was thinking pvc pipes wouldn't roll that well since they usually aren't very straight. Looks like a pretty simple way to make a precision rig!

Yeah. I have been sanding the radius into my fretboards, and it is indeed tedious work.
I think I might be building one of these myself.

Greg Robinson wrote:Nice jig Martin.
Just by the way, in your diagrams, the router bit protrudes below the radius guide, so you will get a radius tighter by however far it protrudes: e.g. if it protrudes 1/4" below, and you use a 10" guides, you will get a 9-3/4" radius on the board. You probably realise this, but I thought it worth mentioning.

So to label the templates correctly would one always just deduct a 1/4 inch from a scribed template?

Greg Robinson wrote:Nice jig Martin.
Just by the way, in your diagrams, the router bit protrudes below the radius guide, so you will get a radius tighter by however far it protrudes: e.g. if it protrudes 1/4" below, and you use a 10" guides, you will get a 9-3/4" radius on the board. You probably realise this, but I thought it worth mentioning.

I think there is some bad math going on.
The cutting face of the bit will run parallel to the radius of the jig giving a radius equal to the jig
Nice Jig,i plan on building one as soon as ol man winter releases his grip.

I used metal electrical conduit instead of PVC which is a bit more stable and durable.

Mikie wrote:

Greg Robinson wrote:Nice jig Martin.
Just by the way, in your diagrams, the router bit protrudes below the radius guide, so you will get a radius tighter by however far it protrudes: e.g. if it protrudes 1/4" below, and you use a 10" guides, you will get a 9-3/4" radius on the board. You probably realise this, but I thought it worth mentioning.

I think there is some bad math going on.
The cutting face of the bit will run parallel to the radius of the jig giving a radius equal to the jig
Nice Jig,i plan on building one as soon as ol man winter releases his grip.

Sorry, that isn't correct, it is running concentric to the jig but a bit inside of it, so if it is offset by 1/4" inside of the radius, then it is 1/4" less

Mikie, we require full names here. Please let us know your full name and we can change your registration information. Thanks!

Speaking of math, something that I find very confusing is how a long compass and a contraption like this can yield the same results.

Right, Andy. The long compass is just plain cool, old-school math. As a matter of fact, straight long compass rails would be just as effective on this jig, AND they could be made adjustable to quickly dial in any fretboard radius.

Well,here is my version of the jig
When I get the rail jig done and test drive it ill post the results
The radius on this one is 12"

Here are pics of the entire jig
along with a scrap sample I did to see what radius it cuts
This jig cuts the same radius that is made on the router jig




The router bit is running parallel to the router jig
The center point of the radius of the cutter is proportionally longer than the center point of the router jig making a parallel cut

How rigid are those plastic arcs?