Before getting to the ski gear (I promise you its here), there’s a touch more background to cover. Just as IM can be found in almost every piece of gear we use, CNC machining is used throughout the industry and one of the reasons equipment has become light, reliable and fast.
Most of the machine work for the ski industry is not used on the actual gear itself. The vast majority of lathe, milling and grinding operations are used to make molds. These molds are everywhere, and represent a large portion of the costs associated with the production of gear.
Computer Numerically Controlled machines, or CNC for short, have proven to be the most accurate and repeatable methods of turning raw stock into finely crafted parts. Designs are produced and laid out with some form of CAD program. CAD is the catchall acronym for Computer Aided Drafting software. AutoCAD is a brand created by AutoDesk and has the distinction of being the ubiquitous term for any CAD work. Not every brand of tissue is a Kleenex.
 is a state of the art machine shop. Jim Poirier, President of the company takes us into the machine room which uses approximately 75% of the floorspace. The area is relatively quiet, very well lit and super clean. Poirier is responsible for the aluminum rollerski wheel hubs in addition to the brass and steel ski tuning tools Jenex designs, has made and distributes.. <p><center><img src=){kind=spacer}
Figure 2 CNC machined parts by Piorier
The actual cutting process is entirely automatic with almost no human interaction. But the set-up requires experienced human machinists. The machine starts out with a known, 3-axis zero point and the G-code describes the finished shape of the part. The machinist must program the dimensions of the cutting tool (depth, length and diameter) to enable the computer to alter the path of the tool to achieve the correctly sized parts. Any time a change is made to a tool (i.e. its sharpened), the machinist must tell the computer if there are any changes in size.
Let’s say we want a finished part that is 1†square. If the CNC machine is told the cutting tool is 1†in diameter, the track of the mill will place the edge of the cutter to leave the finished piece 1†square. If we install a ½†diameter cutter and do not inform the CNC machine of the change, the track will remain the same but our part will now be too big.
The operator inspects the finished parts to be sure they meet the design specifications. The precision and repeatability of CNC machining is important to having a well made rollerski. The wheel hubs on the classic ski are round and cylindrical to within one-ten thousandth of an inch. These close tolerances keep the bearing and clutch races running true after they are pressed into the hubs, a process which takes place at Jenex after the rubber tires are molded onto the hubs. To give the rubber tires something to grab onto and keep from slipping off the hub, square grooves are cut into the hub in a herringbone pattern.
. After machining, the Poirier Company sends the hubs to the vulcanizing shop located in Massachusetts. The twenty cavity mold is designed to hold the aluminum hubs at the center of the wheel and liquid rubber is injected into the void between the hub and mold. The vulcanizing (hardening and stabilizing process) requires twenty minutes for each cycle. The wheels are shipped to Jenex for installation of the bearings, threaded inserts (if used) and the one-way clutch for the classic wheels.. <p>Next stop on the factory tour is Riverside Precision Sheet metal, Inc (www.rpsm.net) located in Henniker, NH. Riverside makes 30 individual parts for the Jenex line. During biathlon training at the Ethan Allen Firing Range I have heard plenty of machinegun fire. The pattern of noise coming from the main building of Riverside had me think this company manufactured automatic weapons. The sound was not made by twin, ring mounted .50 caliber guns, but by a state-of-the-art, punch press. . <p><center><img src=)
Figure 4 Riverside produced parts
Just as Poly-Ject utilizes energy efficient machinery, the 40,000 pound Amada punch press uses only $1.00 worth of power every hour to cut and form sheetmetal ranging in thickness from ten thousandths to ¼†thick. The punch press is also CNC and has the ability to figure the most efficient manner to cut parts from the flat stock.
 larger than the punch. The die supports the material and the solenoid propels the punch through the stock with 22 tons of force removing a bit of metal on the way through. The punch is retracted, the material is moved and another hole is made. The punch and die do not have to be round. They can be rectangular, allowing straight cuts or curved for smooth round shapes in the finished piece. The punch doesn't have to go all the way through and presses the metal for reinforcing ribs to strengthen the parts. The flat stock is supported by plastic bristles and grabbed on the edge and moved into position. The forks for the Aero line of rollerskis are made on this press.. <p>After punching, the pieces are sent to the de-burring room where the edges are smoothed for safety and to eliminate stress riser points from the parts. From here, the flat pieces are sent next door to the bending brake.. <p>Even though a human positions each part in the bending dies, these machines are still considered CNC. The computer uses force gauges and travel to apply the proper force to the part to end up with the desired amount of bend. Most pieces are slightly overbent in the machine to account for spring-back. . <p><center><img src=)
Figure 6 Bending operations (not Jenex part in photo)
For parts where the required bend will not have enough material for the brake to properly shape, the tabs are cut oversized and cut after bending. This post-bend cutting is accomplished at the CNC laser station. This 2,000 watt laser is capable of cutting ½†plate steel at a rate of 36 inches per minute. On the thinner material used in rollerskis, the cut requires only a few seconds from placement to removal. Sitting next to the laser station are tanks of liquid nitrogen which is boiled off and blown out in a high pressure thin stream just behind the beam. This helps keep the parts cool (temper or annealing is generally not needed post cut) and removes the slag or molten material. The laser does such a good job concentrating the heat and is so fast the parts can be picked up with bare hands almost immediately after cutting.
 welds the forks to custom extruded frames for the Aero line of skis before sending them to the paint shop for finishing.. <p><center><img src=)
Figure 8 Frame and fork ready for TIG welding
Eventually, all of the parts find their way to Jenex for final assembly. Bearings and clutches are pressed, split rim wheels are assembled, decals applied to the frames and final inspection is made of the completed rollerski.
After all of the automated and machine controlled production, the final assembly of the rollerskis is all done by hand. Bearings and clutches are pressed into the hubs with a hand controlled (arm-strong motor) arbor press. Any metallic inserts are also pressed into position by a human. Nuts and bolts are snugged down with motorized drivers and the final tightening is done with a wrench.
Figure 10 Racks of finished rollerskis
This piece is the end of the background information pertinent to most all of the gear we use. From now on, the How It’s Made series will have much more ski gear filling the pages. If anyone has questions regarding some aspect of making gear, please leave a comment and I’ll see what I can do to find an answer.
Kevin Brooker
Kevin is 42 years old, married with two children and living in Post Mills, Vermont. He began racing bicycles at sixteen and continued pursuing individual sports. After a six-year layoff, Kevin has returned to athletics racing in biathlon events. He has written numerous articles for FasterSkier, including a series on his return to racing and his current "How It's Made" series.
