Sanding tools are invaluable for shaping, smoothing, and finishing a guitar. But what should you use for different guitar build project tasks? Let’s find out…
What type of sanding block is best for guitar building?
Due to the various sanding tasks when building a guitar, you’ll need a variety of sanding blocks going from soft to very hard in various sizes and shapes. You can make many of these yourself from items you have lying around in the workshop, but some tasks will require more specific/accurate sanding blocks.
A basic rule of thumb is that for square, flat, or sharp-cornered sections, the harder the sanding block the better. If you have a large area that needs to be sanded perfectly flat then the base of an old plane, such as the Stanley #5 (widely available at garage sales, etc.) is a fantastic option. Simply crease a piece of sandpaper around the edges and you're away.
For smaller areas, you can’t beat a solid flat block of wood. These can be cut to size giving you a number of options for different tasks.
If you carefully handle the sanding block, you should be able to sand edges without going over the corners to keep the edges looking crisp and flat. For most hardwoods, make sure that you sand with the grain to ensure that any small scratches left from the sanding process are obscured by the direction of the grain.
For medium sanding blocks, use pieces of cork cut to size. The cheap cork used for flooring available at home improvement centers is a great, inexpensive option.
The best thing about using cork is that it takes no time or effort to shape it into any contour.
To create a curved sanding block, lay a sheet of 120 grit against something that has roughly the right contour, such as PVC or metal piping, or even kitchen crockery. Then sand the block down to create the exact shape needed.
Fret, Nut, and Fingerboard Sanding
There is nothing wrong with using DIY sanding blocks for lots of the guitar build process, but there are some tasks that require more precision. For these, you need specific tools that have been manufactured to ensure that the build is 100% accurate.
For example, let’s consider the fingerboard radius. This is the arc of the fingerboard and is usually measured in inches. You simply can’t make a mistake with this, so you’ll need a dedicated sanding block with the precise radius of the neck you are building.
Some manufacturers provide sanding block tools like these with rock-solid base for sanding as well as exceptional durability. Available in various sizes for specific fret leveling, fingerboard and nut sanding needs.
When using these, you need to attach sandpaper to the sanding block (usually cut to fit the block's shape). Sand the fretboard and frets in a smooth, even motion, checking frequently to ensure the fretboard's radius is maintained. Gradually use finer grit sandpaper as you move from initial leveling to finishing.
And finally, we have the…
Soft and Very Soft Sanding Blocks
These are normally either rubber, felt, or even pieces of leather. And while on the subject of rubbers, one of my favorites is a pencil eraser and it works like a charm for getting into hard-to-reach places. The flat side is great for most surfaces, such as the transition between the headstock and the neck, or turn it on its edge to get into narrower areas.
If you need something a little firmer, get yourself a harder eraser, there are lots of shapes and densities to choose from.
Or, for ultra-fine sanding, use small pieces of leather. It’s tempting to just use the sandpaper without any backing, but from experience, I find that having some type of backing, even just a thin piece of leather creates a far better end result.
