Fachpresse / Zeitschrift: SUSTAIN Magazine Nr. 8

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Tools I love:
Sustain Artikelbild Kurvenlinfix Mini
It is said that a router is the best friend of a luthier. In this article, we present a tool that might just be your router’s best friend, an association aimed at obtaining clean and even routing jobs.
By Martin Koch

Making a plywood or MDF template of the body shape is always my next step after designing an electric  guitar. The template is mounted on the body plank and the shape is cut out as close as possible using the  band  saw. Then I use a ball bearing guided template bit on a router table to smooth the body sides. Or I use a sanding drum with a guide wheel mounted in the drill press. With either method  the ball bearing or the guide wheel follows the template edge resulting a perfectly shaped body. To get this perfection  though the template has to be as smooth and as accurate as possible. Every dent, every flaw will show up on the final piece. Because achieving the required precision by hand is not so easy and also time consuming I often dreamed of a CNC router that would take over this task. Fortunately I recently  discovered the Kurvenlinfix Mini and my CNC router desire immediately was a thing of the past. This tool improved the quality of my templates a lot.



I wasn’t contacted by the manufacturer to write this product introduction but discovered this tool on my own.  I also do not have any relationship with the manufacturer and bought the product at a regular price for my own use. I simply write about it because I love to use it.

The screw-on flexible guide “Kurvenlinfix” was developed  by German carpenter Dierk Söder. It is made of an elastic synthetic material that doesn’t contain plasticizers. Mr. Söder’s tool design company ProTus presented the Kurvenlinfix to the public in 2004. In 2008 the mini version for tighter radii was introduced (this is the tool we show in this article).

This invention has proved to be extremely helpful in my workshop, making it very easy to layout nice, uniform curves.


How to use this toolHow to use this tool.

1. Place a printout of your design on the template material
2. Fix it with some tape strips.
3. Align the Kurvenlinfix Mini to the outline and fix it using 20 mm long counter sunk wood screws with 3 mm diameter.


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4. Follow the body outline and fix the guide as you go.
5. Cut close to the guide using a saw.
6. Flush cut on the router table using a template bit.


The Kurvenlinfix Mini has a cross-sec tion of 12 x 12 mm. Since we are using 20 mm long screws, the minimum template material thickness is 8 mm.

The recommended minimal bending radius of the Mini version is 75 mm so for most electric guitar body shapes you should be able to follow the entire outline except the tip(s) of the body horn(s). Those areas  are easy to shape using a rasp and sandpaper anyway.

The Kurvenlinfix Mini can also be used to accurately convert a convex form into a concave one.  So far the  Kurvenlinfix flexible guide is the only resource available to produce this kind of results.
There are also good news about a product range expansion. As of June 2015 a third, smaller version of the Kurvenlinfix with a cross section of 8 x 8 mm is available. Its called Kurvenlinfix Picco and it allows an even tighter bending radius of 30 mm.

I recommend one 1200 mm long Kurvenlinfix Mini as a start. This allows you to follow most parts of a guitar body outline. When you later buy one or two 600 mm long ones for the cutaway sections you’ll  be  able to cut an entire electric guitar body shape in one pass.


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The Kurvenlinfix products are widely available. Although they sometimes appear under the name “Fisch  Flexiguide” they are always manufactured by ProTus.  More info and retailers can be found on their  website.

Additional information:  www.protus-tools.com


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