The Grintec K2 is a honing guide specially designed to sharpen traditional Japanese plane irons. In comparison to Western plane irons, Japanese irons are much shorter and thicker. They are also roughly wedge-shaped from heel to edge and the sides are also often not parallel. The name "Grintec" is a mix of the words "grind" and "technology".
For example, the iron shown in the photo to the left is made by Tsunesaburo, and the heel end is 67.6 mm wide, but it narrows to 65.2 mm at start of the bevel. The thickness changes from 9 mm at the heel of the iron to 6 mm at the beginning of the bevel. The iron is 102 mm long, measured to the beginning of the bevel. The bevel is ground at 28° and with with the narrowing of the sides including the bevel, the width of the iron at the cutting edge is 59 mm. These measurements suggest how difficult it is to design and build a honing guide that will hold the irons in place while sharpening them.
Max. Iron thickness: 10.5 mm
Min. Iron width: 40 mm
Max. Iron width with adaptor: 83 mm
Max. Iron width after dismounting adaptor: in theory no limit, practically speaking probably about 150 mm
Max. Iron length: 120 mm
Min. Iron length: 60 mm