Basic machine ski tuning
1.) Use a belt grinder to achieve a 1 degree all throughout the ski on the edges ONLY. This step is important because the base bevel will shave off a millimeter of base, therefore edge also if you don’t bevel the edges first. if the belt is worn nicely, you can run the ski flat and rid of any edges that are higher than the base, therefore making it a zero bevel in regards to both the edge and the base. this will give you an idea on the structure of the ski whether its poor quality or good. Then proceed to working the edges to a 1 degree. this takes skill and practice..
2.) On the belt grinder, then bevel the side bevel. This process involves knowing what the side bevel is preferred and can vary depending on the preference and ability of the skier. A 2 degree bevel is safe for most all skiers on modern equipment.
3.) Put the ski in a vice and use a base bevel file and bevel the tips and tails with moderate pressure to achieve a 3 degree base bevel on the edges, then gradually to a 2 degree, one degree, then no filing at all underfoot. use a felt tipped marker and color in the base edge to see how well you are beveling the base edge. underfoot is the tip of binding to heel of binding. The underfoot area of the ski should not be touched by a ski file, it has already been beveled sufficiently from the belt grinder.
4.) If tuning a race ski, take a side bevel tool with a new file and side bevel by hand. This is much more precise than with a side bevel of a belt sander. After that, use a gummy stone and lightly swipe the edge to remove burs.
5.) Depending on if you are racing or recreational, may influence your selection of a stone pattern. (Varying the stone speed and the diamond cuter will provide a variety of possible structures and you will want to experiment a little with an old pair of skis.) Stone grind the ski with a single pass to incorporate the structure into the base material. If you experience any sparking underfoot, that is ok. You shouldn’t have any sparking on the tips or tails. An experienced tech knows that sparking is a normal. it also means that you achieved perfect zero base bevel contacting perfectly with the edge.