Yes these are expensive – you only get x1 file for this price! But no one else currently offers them other than Vallorbe.
Vallorbe square file for sharpening square ground chain. Granberg filing guide recommended if you want to square grind your chisel chain. This is for x1 chisel bit file – the files are x12 more expensive than normal chainsaw round files probably to do with the much lower production volumes. Square ground chain is incredibly hard to sharpen. However you can return square ground chain to general chisel chain by using a round file to sharpen it.
Bevel angle 75° (Pro sharpening).
Using the Granberg clamp on file guide is essential for getting this type of chain sharpened right as then you can set and duplicate the complex angles. There is an excellent guide on how to do this here. If you are serious about square ground chain you need to read it.
The term “square-ground filing” refers to the process of using a flat bevel file to sharpen saw chain cutters by hand. (Mostly full chisel chain)
The full chisel has square-cornered teeth, splitting wood fibres easily for fast, efficient cutting in clean softwood.
Square-ground filing is much more challenging than round file filing and requires different techniques.
Example with 45°: the chisel file angle can vary from 30° to 45°
full chisel chain sharpened with flat files is less forgiving of errors compared to round file,
it is important that the top-plate cutting angle and side-plate angle be precise.
Optimum full chisel chain performance in clean, soft wood is obtained with both angles at 50 degrees.
Chisel chains also have a high kick-back risk due to missing safety chain elements and are more sensitive against dirt/rocks
and are therefore suited to professional timbers and for competition (Timber Sports).
Do not forget that square-ground filing requires the use of a round file to clean out the gullet:
The best sellers are the double chisel and three-square bit files with precise bevel angles.