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Stone Grinding & Structuring

Stone grinding is the one machine based operation that is outside of the scope of a DIY tuner & should be done by a competent shop technician.  
 
The reasons for a stone grind are:
  •  If the bases are overly concave or convex
  •  If the base edge angle is over bevelled
  •  If you want to reduce the base edge angle
  •  If the base edge is badly damaged
  •  If the structure on the base has worn too smooth
  •  If the base structure pattern/depth doesn't match the snow conditions (racers only)
It's normal for any stone grinding machine to leave some 'fuzz' of p-tex fibres, the amount depends on the skill/care of the machine operator, the wear state of the grinding stone & also the structure pattern utilised. The fuzz needs to be removed if you want to maximise the skis glide. Skiing on them a lot will eventually accomplish the same thing but they will be slow until smooth so it’s best to do this manually.
 
You can knock down the fuzz on the structure by using a steel or brass brush to open the structure up & then fibertex pads in varying coarseness grades. The brush helps pull out the fuzz in the 'valley' of each striation. The fibertex pad removes fuzz from the 'peaks' and also knocks them down somewhat, smoothing out the structure. If the grind is very coarse, it will involve a lot of work to remove the fibres.
 
Following a stone grind the edges need to be re-set as above & since the stone grind removed all the existing wax from the base you need to treat the skis as though they were new so multiple waxings are required. Therefore refer to section 9 in the ‘Base Tuning’ section above & then hot wax with your chosen wax for the conditions. Remember when building up the wax in the base that it’s helpful to wax with very low temp wax at least several times using a sharp plastic scraper. When you scrape off this hard, cold wax it does an excellent job of pulling off all the old coarse hairs left over from the grind. In fact, some technician’s refer to extreme cold wax applications as ‘a poor man’s stone grinding’ because the cold waxes help to smooth the base. Again, future occasional applications of cold waxes are needed in order to eliminate coarseness from a base.
 
Structure
Structure is the name given to the fine longitudinal grooves in the base of the ski that breaks the surface tension of the film of water between the ski base & the snow. Without the structure's action the ski would 'stick' to the snow. Not only do the grooves break the surface tension but they also act like the tread on a car tyre to remove/shed the water away efficiently. For a high-end ski racer the pattern & depth of the structure has to be chosen to match the conditions & is as important to their performance as tyre choice is to a Formula 1 car.
 
In addition to flattening the bases it is the stone grind process that puts the structure in the ski base as the grinding wheel has a pattern on it which it then cuts in the base. A number of different structure patterns can be specified, each designed for different conditions, however in the UK you’ll be hard pushed to be able to specify the structure that you want.
 
It is possible for the DIY tuner to add or enhance the structure of the ski to improve the performance, typically for wetter snow (like in the spring) to help drive out the extra water. This is usually done by one of the following methods:
  •  prior to waxing use a very stiff stainless steel brush for a few passes from tip to tail to scratch in the additional grooves.
  •  use a Kunzmmann structuring tool to cut in the addtional grooves.
  •  use a Snoli riling bar/file to cut in the additional grooves.
However, unless you’re a competitive skier for most people it’s far easier to wipe the base over with Zardoz Notwax for extra water shedding.
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