Router Tutorial

By Derek Neil
Photography provided by Aaron Goodwin

 

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Router bits, size, quality and types,
Using templates & guide rails, 
Making your own templates,

 

Making templates

 - First making a plexi glass (acrylic) template which will be used to sink the bridge into the guitar. This tutorial can be applied to making  a neck pocket template, humbucker, single coil templates, any recessed trem routing template, and some rectangular or triangular control cavity templates.

Special note: Some lower grade acrylic's (plexi glass) will require cutting and routing at slower speeds then wood or it will melt and be difficult to get a clean cut line which is essential to a good template

 

- Being Square: 

 

After you've taken your time and carefully scored all your lines at perfect 90 degree angles to each other you should end up with something like the picture to the left. The line with the dotter red is the scale mark position for the bridge which will help me line up the template on the guitar in addition to the center line which will line up with the center line on the guitar.

THE most important aspect about your plexi blank is that 2 edges need to be as close to perfectly square as possible. I used a machinists square to find my 2 square sides (hence the 90 degree arc) and put X's on the other 2 junk sides. 
HINT: cutting plexi glass or any acrylic requires a very fine very sharp blade.
Next Peel the film off one surface only and find the aprox. middle on each of the 2 square sides, then use your square and an exacto knife to score a line from each of the 2 sides to give you a cross that should now also be perfectly square in the middle. 
Now that you have a square center point established measure everything from these 2 lines and score little marks with the knife, for me that would be the width and length of the bridge so i'll have 4 marks, that will then be scored into full lines with the help of the square. HINT: DON'T use the end of the ruler, measure from a unit on the ruler, I always measure from 1cm(10 mm), then just add ten to what ever measurement you're trying to mark. Once you get all your marks made from either center line, use your square on the 2 good edges and score each line, so for me I had to score 4 lines in addition to the 2 center lines I started with.

  

 - Prepping for routing the template:

Once you've got all your scoring done, measure it a couple times in every possible way to make sure you didn't mark something wrong in the first step, trust me, I actually caught a mistake I made during this tutorial and fixed it before I ruff cut it out and it was to late. 

So obviously the next step would be drill a hole in the middle of the template that is to be empty. Hold your work down, acrylic likes to get stuck on a drill bit, shoot up and crack, then if you have access to a scroll saw put the blade in the middle and cut out as much as you can but stay 1/16" - 1/8" away from the outside scored lines. Do not cut your way into the template if you don't know how to remove the blade and start in the hole.

Next you'll be needing a couple of scrap guide rails, I've used purple heart scraps I ran through a jointer to get a straight edge, then cut the pieces for making this template. A total of 4 pieces it needed for this, 8 would be needed to make the 2 rectangles for a humbucker template ect, etc. Use some good double stick tape, line them up with the scored lines then press down. Measure again to ensure you've placed the rail the correct distance from the center line of the template. Keep measuring after you attach each piece and once it's in place be sure to squeeze it down good so that the tape holds the rail in place.

 

After careful placement, and measuring more then a couple o times, you should end up with somthing like the image to the right

 

- Finally making the template:

 

Using your router setup in a table, in a wood box or table, use a flush trim bit and trace the rails to get a smooth straight line for your template. I've decided to go with a tiny little 1/4" flush trim bit, which will give me nice tight little corners, and is also the reason  why I removed so much material before with the scroll saw. A 3/8" or 1/2" flush trim bit is also appropriate depending on the template.

THE KEY, to following the rails is NOT to push hard, but just to let the router do all the work, gently guide the template along all 4 corners (always moving against the rotation of the bit). By the end you should have your very own miniature snow storm, and a near perfect and smooth rectangular routing template.

 

- Using the template:

For those of you that didn't quite understand what this template was for here's some shot's of it being used in action. Lining up the template with the center line of the template and the guitar, and the scale mark on the guitar and the template. Again using the bushing method to transfer the template design onto the body for a very shallow rout. 

 

Starting in the middle, tracing the perimeter, then checking half way through, I'm only routing 1/16" deep to set the bridge in the correct position for the angle of the neck on this guitar.

 

Making Body Templates

 - Making body templates 

 Body templates can be made a couple of different ways. Either tracing an existing body with a flush trim router bit, or a special pencil. Drawing one free hand on the computer or with a pencil. Or they can be made at the same time the body being copied  is sanded to shape.

Using a flush trim bit on a finished guitar to make a copy of the outline onto a plywood board can often damage the paint job on the guitar and is not recommended unless you're intending to repaint the guitar (see side of black guitar to right). These indentations from the bearing are also left on raw guitars, but are more easily sanded while still in production / before being painted. 

You can also use a flush trim bit to copy control cavities, bridge routes, pickup routs.

Tracing a body with a pencil can be done by sanding a pencil in half, the sanded side of the pencil is the set against the side of the body to draw an outline of a guitar, this eliminates trying to guess what angle to hold the pencil at to correct for the point at the bottom. 

Once you have your design traced onto the plywood it's ready to be cut. If you traced the design from another guitar in a store onto paper then cut it out carefully and trace it onto your plywood or plexiglass. Cut out the body shape on a band saw or scroll saw about leaving about 1/8"(3mm) from the line. 

Lastly use a belt sander, preferably a stationary one to sand into the line. Take your time with this, make sure all the curves are smooth and continuous with no flat spots. Use the highest grit paper you can find for your belt sander (usualy 150-200)

 

Links
Prev The 2 types of routers, general use recommendations & hand held vs. table mounted,

Next

Router bits, size, quality and types,
Using templates & guide rails, 
Making your own templates,