As I’ve made the transition from a consumer of stone grinding to a creator under Zach’s guidance, I’ve gained some unique insight about skis and stone grinding that is worth sharing.
While I have been studying structure and stone grinding closely now for over a year, my hands-on training began in July when I made a trip out East to be immersed in the Engineered Tuning Life for 8 days. Zach and I had a lot to go over: details about our collaboration under the Engineered Tuning name: stone grinding, ski selection and retail sales. I also had to figure out the pesky details of the stone grinding thing.
The schedule was basically 9AM to 10PM on the grinder and I received an intensive course on operating the machine: how it works, taking it apart, nursing the best structures out of it along with lots and lots of practice.
A quick explanation of the stone-grinding process is helpful at this point. A big stone wheel made up of abrasives and epoxy spins on the machine. A very small diamond cutting blade can move across the stone at varying depth. The machine “dresses” the stone by advancing the diamond into the stone so it cuts tiny channels in the stone as the stone spins, creating a pattern. After dressing, the ski is passed through the machine, and the stone cuts the pattern into the ski, creating structure. By varying the depth and speed at which the diamond moves across the stone, almost infinite patterns can be created.
The stone grinding process begins by flattening the base of the ski and removing all traces of existing structure (polishing). So the result of the first step is a flat ski that is “blank”. This blank is then ready for “final structuring” where one or more layers of precisely machined structure are cut into the base.
I have always been intrigued by the stone grinding process, but my knowledge was always limited to the racer's perspective. I was a very educated user: I know what a good grind looks like, what different structure patterns accomplish and how often skis should be ground. However, everything I knew about the actual grinding process was what I had observed in a few random glimpses into the grinding shops I had visited. The only thing I saw was some guy feeding skis into a really fancy machine and taking them out on the opposite end. Seems simple enough, so why is it that only a few people can put out top-quality grinds?
Seeing Zach at work and learning the process was illuminating. My experience as a consumer of grinds had confirmed the conventional wisdom that there are good grinds and there are REALLY bad grinds. I never understood how it was possible to create a bad grind since the machinery involved seemed so capable. What could possibly go wrong? Push the buttons, feed the skis; none of that seemed very difficult. Under Zach’s guidance, I managed to be a successful stone-grind monkey capable of feeding skis and pushing buttons in about an hour, so where was the hard part?
The Tazzari grinder is amazing. The model Zach is selling me is the RP-13, which is “numerically” controlled as opposed to analog. Basically, the computer control system does some very nice things like adjust the RPM of the grinding wheel as the diameter changes so that the conditions can be precisely controlled and repeated. It has a very precise stepper motor that controls the diamond as it cuts the stone.
Like many things Italian, there are some quirks, but they are overwhelmed by the art of the entire creature. The purple and green exterior combined by a frustrating set of nonsensical menus in the control software grated on me at first, but as I started using it I immediately forgave those transgressions. The machine is a work of art. It is capable of absurdly precise work and I was constantly amazed at what it could do. I fed it skis, it spit them out the other side, and as long as I let the machine do the work, they came out perfectly every time.
So, if you have a monkey, some skis and a $25,000 piece of equipment that can do high-precision work, then what is the challenging part? At about 10PM on day 2 of my time on the grinder, Zach introduced me to the "final structure" step of the grinding process. I was humbled and quickly realized why it takes a rock star to make good grinds. While the machine’s precise controls create an incredibly powerful tool that can consistently work at resolutions of 0.01mm, the variable that cannot be precisely controlled is the shape of the diamond as it cuts through the stone material.
The key to stone grinding is creating those final structure patterns consistently and effectively. The machine does most of the work and the RP-13’s unique precision makes it easier, but the one variable it can’t control is the shape of the diamond as it cuts. As the diamond cuts through the stone, it gets dulled on edges, rounded, sharpened and sometimes even sheared. Unbelievably, with the aid of a magnifying lens, you can easily see the erratic shape of the diamond as it cuts into the stone at a depth of 0.01mm. If the shape of the diamond is not right, the cuts it makes into the stone are either too shallow, too aggressive or asymmetrical.
This is why it is so challenging to produce consistent grinds - the diamond is somewhat unpredictable as it wears and while the machine is incredibly precise in how it holds the diamond during the cut, it cannot control its shape. Since the diamond shape dramatically affects the outcome of the grind, the monkey has to graduate to the rock star-level in order to create consistent, quality grinds. The challenge is managing the diamond so that it has the correct shape as it dresses the stone.
As we repeatedly dressed the stone for final structuring, I got to observe good cuts, bad cuts and mediocre cuts with Zach looking over my shoulder and explaining it all to me. After a few hours of this, I began to see things clearly on my own and by the time I finished my week of training, I had become a confident monkey, capable of creating quality grinds following Zach’s grind menu.
It will take us a while to get to Zach’s level – being able to develop new ideas and intuitively operate the machine – but I am excited and confident in our ability to create top-quality grinds based on the formulas Zach has given us. We look forward to learning more from Zach working with him on his visits to Colorado in October and West Yellowstone in November. We can't wait to get our hands on that machine!
NS Checking out his work on Zach's machine in July