Professionals and Amateurs Together

Sharpening Back Saws


Where does one get three sided files with grooves to the edge for sharpening back saws? — Dave Frechette


Bob LaCivita replies: When sharpening a back saw you must first determine the number of teeth per inch or points per inch (PPI). When sharpening my dovetail saws which range from 15-21 PPI, I use a 4˝ double extra slim triangular file. When sharpening a 9-10 point saw I use a 6˝ extra slim file.

A simple way to determine this is to set the file in the gullet and visually see if the file fits. If it fits it should work.

I am talking very fine mill files here. The question asked about grooved files and I do not know what that means. Remember finding the file is the easy part. When filing the saw use a saw vice or saw chops. File every tooth pointing toward you with the same number of strokes keeping the pressure even. Turn the saw around and repeat. The teeth should look even and the gullets should be the same size. Try the saw.

If it pulls left or right you could have a few problems.

  1. The set is uneven. You can get a setting tool and reset the teeth. If the saw is fine (16-20+ PPI) you have to hand set the teeth with a milled gauge (you have this made) and a punch.
  2. The filing is uneven. Back to the saw vice. The saw needs to be jointed. By laying a fine mill file on top of the teeth and gently cutting them down until they are even along the length of the saw.
  3. Re-file the teeth. Remember this is very painstaking and patient work. Be careful and use light strokes. I have seen many bulls in the china shop ruin very nice saws.
  4. I have never heard of grooved files. You can sharpen a saw with a regular old mill file. There is a Swiss company called Vallorbe that make a groove file — These files are for cutting grooves into a piece of work. You can check this out on their web site by going to the applications menu Sample 1 & 2. They look like very precise mill files.
Tags: Sharpening, Tools