Sharpening your Saw

There are a lot of good and elaborate resources about saw sharpening on websites and in books so here is an overview of what helps me maintain a good cutting saw. If you just bought an old saw you’d like to sharpen, or your saw is in a bad shape also read Regular Maintenance – Advanced Sharpening.

Keeping your saw sharp

If you intend to maintain the sharpness of your well functioning saw , the simplest thing to keep your saw sharp is to use an appropriately sized saw file (fig.1) and make one light and equal pass in every gullet.

fig.1 The correct file size width ‘a’ is double the teeth largest side

Try to keep each stroke the same length to keep all the teeth the same height. Also try to replicate the rake and (if crosscut teeth) fleam angle of the teeth (see fig.2). By fitting the file into the gullet and feeling what the angles are, hold the file in that same angle through the whole sharpening process. You can use a filing guide for this, see ‘Making it easier’ below.

fig. 2 rake and fleam angles of crosscut teeth

You will need a way to hold the saw while you file. A saw vise sturdy enough to keep the file from chattering gives the best results. Keep in mind the bigger the teeth the sturdier the vise needs to be. (Click here to read more about making a saw vise)

Saw file sizes

Choosing a file to sharpen your saw can be a bit confusing. There area few different files that would work on a a given tooth size because there are different lengths and widths, and there are double ended files. I will describe here the single ended files.

fig.x a single ended saw file

There are 4 basic sizes that come in different lengths, whereas the most important size is the width of the file. So when picking a file, look at the width you need and then pick a length you’d like.

fig. X the right file width

The basic sizes from big to small are called ‘Regular’, ‘Slim’, ‘Extra Slim’ and ‘Double Extra Slim’. To give you an idea of the overlap within these 4 categories look at the two tables below. A= length and B= width

Bahco Extra Slim Taper
Bahco Slim Taper

When you need 8.5 mm width you could either choose a 7″ (175mm) Extra Slim or a 6″(150mm) Slim. In this way you can buy what you need from what is available or which is at a better price.

For small and medium backsaws the 100 to 125mm are long enough. For the bigger saws 150mm is a nice size. For really tiny teeth from 15 points per inch and up the triangular needle files are very useful. They come in length of 140 and 160 mm and need to be smooth or cut 2.

Saw file handles

Any file handle will do as long as it fits the tang of the file. Many files tangs are hexagonal and will fit a round hole. These Holtzappfel style handles are very comfortable for sharpening.