Posted on September 04, 2011
GET GOOD LIGHT
Always try to use good backlighting when checking bases with a true bar, otherwise it'll be hard to read accurately. A bright window, fluorescent overhead light, or even a light bulb (60 watts or equivalent) positioned a foot or two beyond the ski or snowboard tip will do the job.
TRUE BAR TRICK
When checking for flatness on a clear p-tex base that you suspect is concave, it is sometimes hard to determine if the light under the true bar is from the concave area or just light reflecting through the p-tex. Try placing the true bar in the middle of the base, parallel to the edges, and then slowly rotate the bar 90 degrees until it sits across the width of the base. If the base is flat, the true bar will rotate smoothly...but if it is concave, it will catch on the edges of base material as it turns. Also, ski straps or watch bands are handy for bundling up excess electrical cords that otherwise sprawl across your workbench.
-Tim Mochizuki, Gardena, CA
BASE FLATTENING TIP
When checking for base flatness with a true bar, use a water-based felt tip pen to lightly mark high or low spots. This makes it easier to pinpoint and concentrate on problem areas and save base material elsewhere.
-Kirk Carter, Henderson, KY
Ever have problems with your roll pin (used to check for base flatness) rolling off your workbench or ski? Try dripping a small blob of wax onto the roll pin at some point...this small speed bump will stop the pin from rolling away.
-Craig Talarico, Johnstown, NY
Always check skis to make sure they are also torsionally flat and true...you don' t want a twisted ski because it'll never perform correctly. They traditional way to check this is to hold both skis base-to-base as lightly as possible (don't squeeze . em tight or you'll cancel out any twist that may exist). Then check if the skis contact each other all the way across the base at both the tip and tail. If so, good....but if not, and the bases rock slightly against one other, at least one ski is twisted. Another way to check is to hold each ski against a large flat mirror or window. If each ski sits flat on the glass when lightly held against it (don't press), then they're okay. If either ski rocks even slightly, check out another pair of skis because you can't correct this structural problem.
-Mark Sewell, Miwok, CA
Many snowboards, regardless of core material or construction, will warp up on the front toe edge and the rear heel edge after being ridden a few times. This is sometimes unavoidable given the board's width. Always flatten these bases by hand and follow this natural warpage, otherwise you'll remove too much base material and affect the board's flex and strength.
You’ve just bought new skis and they look great…the edges shine and the bases are structured and waxed. You can’t wait to launch ‘em out of the start gate. But are these rockets really ready to rock? Probably not, unless you and your ski shop took time to make sure they’re prepped right to meet your particular needs.
One Tune Fits All?
After construction, new skis are stoneground at the factory before being wrapped, packed and shipped off to shops. This is done to flatten bases and impart a generic structure. They’re also run through a ceramic disc grinder to bevel and polish edges, followed by a quick wax job with a buffing machine. In short, they’re machine-prepped en masse in a time and cost-effective way, following a formula designed to meet the needs of as many different racers and snow conditions as possible. But will a “one tune fits all” approach give you all the horsepower those skis can really deliver?
In speaking with a handful of top shops around the country, all agreed that you may risk getting shortchanged in performance unless you double-check foracceptable base flatness (not to mention appropriate base structure, and accurate edge bevel angles).
Acceptable Base Flatness
Since the advent of wider shovels and cap construction, skis have more frequently arrived in shops with slightly concave bases (although less occasionally, convex)….especially near tips and tails. This is due to production, design and material challenges, such as: the inherent thinness of tips and tails; molded topsheet ridges, tubes and other design features; diverse expansion/contraction rates of various ski materials; and the way the ski ‘cures’ between the time it leaves the factory and arrives in your local shop. It is unlikely you will get the ski completely flat even after removing excessive material, and the consensus of top tuners is you don’t need to. Try for at least 3/8” (9mm) of base flatness in from the edges and be sure to bevel the edges according skiing type and you’ll be fine.
Convexity, although not so commonly encountered, can usually be completely removed by hand or stonegrinding. Concavity, on the other hand, sometimes can’t be completely removed without also removing unacceptably large amounts of base and steel edge material…especially when it’s 1mm deep or more.
Greg Guras (owner of A Racers Edge in Breckenridge, CO) addresses this conundrum by aiming to get bases flat across 2/3rd’s of the ski width. On a 3”-wide ski, for example, this would mean getting the base flat 1” in from each edge. Jim Deines (owner of Precision Ski in Frisco, CO) and Leif Voeltz (owner of The Fifth Season in Mt. Shasta, CA) try to get bases flat at least ½” to ¾” in along each outside edge. If the ski still exhibits any unwanted edge grab after that, a very small additional amount of base edge bevel (1/2 degree or so) can judiciously be imparted near tips and tails.
Mike de Santis (at Summit Ski & Snowboard in Framingham, Massachusetts, and former World Cup race service technician for Hillary Lindh & Volkl) deals with concavity by first beltsanding bases to slightly remove high steel edges, then stonegrinding with sufficient pressure to counterflex concave base areas until a uniform structure appear across the full width of the ski. While the ski may still remain slightly concave afterwards when unweighted, racers find it feels and performs like a flat ski once they climb aboard.
If you can’t get theflatness you want by hand tools or locally at a shop, you can send gear to one of these shops:
Summit Ski & Snowboard, Framingham, MA
Mike di Santis
A Racers Edge, Breckenridge, CO
Precision Ski, Frisco, CO
The Fifth Season, Mt. Shasta, CA
FLAT SNOWBOARD BASES?
By and large, many snowboards have convex bases when new. If they're only slightly convex, they can be flattened by hand or machine. If they're extremely convex, don't try to scrape or grind them completely flat unless you really want to see what your snowboard core looks like. Instead, strike a compromise and flatten it part way...for freestyle riders and spinners, a little base convexity actually makes the board easier to ride. If you're a racer, however, flat is where it's at, so shop around until you find a board with a base that looks flat as Kansas.
FLATTENING BASES ON SKIS & SNOWBOARDS
In the past, the bases of traditional sidecut skis were pretty easy to get flat from edge to edge with the help of a stonegrinder, wet belt sander, or hand tools like the base flattener tool, steel scraper or sandpaper and block. But the advent of snowboards and wider skis has made achieving a flat base more difficult...and, in some cases, almost impossible. Constructing wide skis as well as snowoards makes it tough for manufacturers to prevent a certain amount of warpage from creeping in during the curing process. The result is slightly concave or convex tips and tails. If this curvature is very slight, it can usually be removed with base flattening tools...but if more pronounced, it can be difficult to completely remove without also removing unacceptable amounts of p-tex or steel edge material in the process. Sometimes you have to accept a compromise between what's workable and what's wreckable...but still rideable.
Frequently you'll find two concave pockets on the base of a snowboard that correlate directly to bindings mounted on the top. Commonly known as 'binding suck', this is a condition created by the binding screws pulling up those sections of the snowboard. Don't bother trying to sand or stone grind your snowboard base perfectly flat in hopes of removing this concavity...it'll remove much too much base and edge material from the rest of your board. Just tune your bases as though these areas didn't exist...chances are you won't even notice 'em when you're shreddin'.
SKIVISIONS BASE FLATTENER TIP
I have a question about the steel cutting blade on the SkiVisions Base Flattener tool. When flattening convex (base high) skis, it only comes in contact with p-tex, which it cuts and flattens pretty easily. But on concave (edge high) skis, won't this same steel blade contact the steel edges and get dull quick? What do you do about that?
-Frank Wiles, Pittsfield, MA
Good question...and timely, too...since skis these days are wider than ever, and often come from the factories a bit concave at the tips and tails. Our advice?
First off, check the bases with a true bar, and note any concave sections. Next, using a flat mill file (or an edge tuning tool with a mill file insert), file these sections until the edges are at least flush with the p-tex base where it abuts the steel edge.
Then, bevel the steel edge...a 1-degree base bevel should work fine. Start working with the SkiVisions Base Flattener, using the steel cutting blade insert...but not too much! Stop as soon as you feel it trying to bite into the steel edge.
Now, repeat all the above steps as necessary until the edge and p-tex are both flat for about 1/2" width on each side. If the base is still a litle concave in the very center, it shouldn't affect ski performance appreciably for recreational riding.
The best option, of course, is simply to take a true bar with you when you buy new skis. If the bases are concave, ask the ski shop mechanics to grind 'em flat before you buy 'em...then it'll only take a little touch-up work with the Base Flattener to keep 'em flat throughout the season.
BASE SANDING TIPS
You can use silicon carbide sandpaper to flatten p-tex bases. To flatten a convex (high or crowned) base, start with a coarse (80 grit) paper wrapped around a sanding tube or block to quickly remove excess p-tex material. Then switch to progressively finer grits (100, 120, 150, 180, etc.) to finish. After sanding, be sure to remove p-tex "hairs" on the base by brushing with a brass, bronze or copper brush...followed by medium and fine scotchbrite or fibertex...followed by an omni-prep pad. Finish by waxing bases as usual.
You can also structure bases with sandpaper. In general, use a coarser grade (100 to150 grit) to create a coarse structure (best for wetter snow)...and a finer grade (150+) for a fine structure (best for drier snow).
LONG SMOOTH STROKES
A common pitfall that you should avoid when base sanding is a "back and forth" movement...it results in twice as much sanding in the middle of the stroke as on the ends. To sand evenly, wrap silicon carbide paper around a sanding block and use long, one-way, overlapping strokes...always in a tip-to-tail direction. Start with coarse grit and progressively work up to a finer grit. Be sure to scrub the bases with a Scotchbrite pad afterwards to remove p-tex hairs created by the sanding.
Sanding paper and scotchbrite pads are very helpful for base work, but if you don't apply even pressure across the full width of the base they can do damage. If you don't have a sanding block or tube for this, use the wood handle on your wax brush.
-D. Salera, Mulino, OR
SCRAPING BASES FLAT
Steel scrapers have long been used to flatten p-tex bases...especially before the advent of stonegrinders and other new hand tools. They still are popular among some technicians...although they require more skill to use properly. Two important tips for using steel scrapers are...1) keep them sharp with a good burnishing tool...and 2) if you use a thin scraper, hold a file behind it to prevent it from flexing and cutting unevenly into p-tex material.
To sharpen a steel scraper, I clamp a lathe file (face up) in my bench vise so it sits about 1/8' below the top of the jaws. This ensures the edge of my scraper won't slip off the side of the file as I draw it along to sharpen it. To keep my steel scraper rigid so it won't flex when scraping bases, I clamp a side edge file guide (#TEQ-0 for example) to the back of the scraper about 1/4' above the scraper edge with two 1' c-clamps. I leave this on even when sharpening the scraper with a file.
-Lynn Johnson, Ketchum, ID
LINEAR BASE WAVES
Most commonly found on nordic race ski bases, these are ripples or waves that appear down the length of a ski base. They can usually be spotted by holding a ski base up with one end held up to a window or light source, and the other end held near your eye. They detract from good glide and therefore should be removed. This can be done by taking your skis to a shop technician who is very experienced with stonegrinding, or by hand using a base flattener tool, steel scraper or sanding paper and block...all of which are positioned and worked at an angle diagonal (rather than perpendicular) to the length of the ski. This helps remove the tops and troughs of waves or ripples.
GETTIN' RID OF RIPPLES
To remove base ripples that make your skis act funny on snow, wrap sandpaper around an absolutely flat 10" file. Holding the file at an angle across the base, pull it in long smooth motions down the base. Then reverse the angle and pull in the same direction. This will help flatten a base and remove ripples.
-Wina Sturgeon, Canoga Park, CA
Base flatness is critical, yet flat filing is a primary source of convex bases...even for experienced technicians and racers. The cause is flexibility of the files, assuming you don't have a better tool for flattening since files are really best for filing steel edges, not p-tex. Two files together, however, are virtually unbendable...so I rubber band two files with a wood paint paddle in between together. The wood prevents the files from dulling each other and you still have two file surfaces to work with.
-Scott Irving, Cape Elizabeth, ME
MAIL ORDER FLATTENING & STONEGRINDING
If you can't get the quality flattening or stonegrinding you crave locally, here're some shops you can send your skis to for quality work. Call them for details and rates.
Precision Ski, Frisco, CO Call (970) 668-3095, ask for Jim Deines
A Racers Edge, Breckenridge, CO Call (970) 453-0995, ask for Greg Guras
Rossignol Skis, Williston, VT Call (802) 863-2511, ask for Jim Fredericks
Precision Ski, Frisco, CO Call (970) 668-3095, ask for Jim Deines
AVOID THE "FUZZ"
Getting bases to glide faster is the perpetual quest of any serious tuner or racer. One key to this is thoroughly removing microscopic p-tex fuzz or hairs on your p-tex base. After flattening and/or structuring (whether by hand or stonegrinder) there are literally thousands of polyethylene hairs left attached to a p-tex base. To remove these, the base first needs to be lightly scraped with a sharp metal scraper (Swix's razor scraper is ideal for this). Next, rub the base with a fine scotchbrite or fibertex pad backed by a rigid scotchbrite holder or sanding block to ensure even pressure is applied across the full width of the base. Follow this with rubbing the base with an Omni-Prep pad. But now, even after all these steps are taken, there may still be some p-tex fuzz left on the base...whaddaya do?
Ski 'em off! According to the Fischer nordic technicians, the Italian Nordic Ski Team hires people to ski 30-40km until the bases ski fast. The Norwegians do the same, but feel it takes more than 30-40km. In any event, the snow abrades away the p-tex hair and the skis get faster.
REMOVING P-TEX HAIRS
Here is an easy way to remove unwanted p-tex hairs from your ski or snowboard base after sanding. Take a propane torch with a flame spreader tip, and, using a soft (cool) flame, make one pass down the base. Keep the flame about 2' above the base and move it along as if you were painting with a paint brush. The base will stay cool, but any p-tex hairs will melt into little balls. At this point, hot wax the ski, let the wax cool and scrape it as usual...the scraping will completely remove these p-tex balls.
-Ray Yusi, Sherborn, MA
POPPING P-TEX HAIRS
You can sometimes help remove unwanted p-tex hairs after any sanding by hot-waxing your base with a very cold hard wax (Swix blue or colder). Iron it on just enough to melt the wax, but try not to heat up the base much. Then take the ski or board outside to rapidly cool it. This makes the wax more brittle. When you scrape, p-tex hairs will sometimes "pop" off with the flakes of excess wax.
Although the finished condition of ski and snowboard bases when they leave the factories has greatly improved over the years, it's still wise to look 'em over good before buying. Some factories take more time finishing bases than others. Volkl, for example, runs their race skis through a stone grinder 16 times (at increasingly finer settings) to produce some of the silkiest bases and edges. K2, Head and Blizzard make about 12 passes through stone grinders with their skis, and Dynastar makes 10-12 passes with a belt sander that begins with a rough 80 grit belt and gradually works up to a smooth 320+ grit belt.
Here's a few quick ways to check the base finish in a shop. First, check for base flatness (side-to-side) with a true bar...run it down the base from tip to tail looking for high or low spots, concavity or convexity. The base should be absolutely flat.
Second, lightly drag a fingernail across the base from center to the edge. Do this without looking at the base and try to feel any change in the finish when you go from P-tex to steel edge. Ideally, you shouldn't...the edge should be polished smooth without striations or roughness left by factory grinding wheels or sanding belts.
Third, if you have a small hand lens, check the base for the presence of any loose P-tex hairs...none should be visible (although they may be hard to spot since the bases were probably buff-waxed at the factory).
And speaking of this, be aware that new skis are only buff-waxed at the factory...not hot-waxed with an iron. Buff-waxing is fast and convenient for manufacturers, but does not melt wax deep into the base material, so it wears off very quickly. Take time to hot wax your new bases repeatedly before taking them out on the hill.
AFTER THE GRIND
According to World Cup technicians, you'll win or lose a race more because of the preparation you do after a stonegrind than from the grind itself. Right before a race, don't go get a stonegrind because your skis will actually be slower until you've spent enough time fibertexing, waxing, scraping , brushing and skiing on 'em to achieve a really polished and fast base.
OTHER RELATED TIPS
FAST OLD BASES
Many racers think that stonegrinding is the key to fast skis...but this can sometimes be a mistake. At the World Cup level, skis are rarely stoneground...sometimes only once at the beginning of a season. Instead, they are well-waxed and brushed on a regular basis. Although the structure wears down over time, the surface of the base becomes more polished and faster as a result.
MORE SPEED MORE QUICKLY
In the past, many race skis seemed to take whole season of fibertexing, waxing, scraping and brushing...plus quite a few days being skied...before they got really fast. But with some new preparation techniques, skis can be made to get faster quicker. This was demonstrated in the nordic ski racing circuit recently when a world championship race was won by former champion Bjorn Daehlie on new skis fresh from the factory, followed by a little preparation. Although this occurred on nordic skis, the same procedure would likely prove true on alpine skis and snowboards as well since they all use similar (p-tex) base material.
Here' s a summary of what steps were taken. First, the skis were stoneground the day before the race by a world-class nordic technician...followed by rubbing with an omniprep pad. Then they were waxed, plastic scraped and brushed 25 times with a soft high-fluoro wax, before applying many layers of the wax of the day. In testing, these new skis proved faster than any of Bjorn' s older race skis.
Not all of us, of course, have access to world-class stonegrinding or unlimited supplies of high-fluoro wax! But the use of omniprep pads to remove p-tex fuzz (microhairs on a base) after fibertexing can probably help improve glide significantly on almost anyone. s skis or boards after stonegrinding. And the repeated application of wax to a base (the best quality you can afford), followed by scraping and brushing, cannot be overemphasized. Granted, rarely can we afford the time or wax to make 25 applications of wax...but, if possible, make at least three, and wait thirty minutes or so before scraping each time. In test after test, and race after race, it has been proven time and again that frequently-waxed bases will outperform those less-frequently waxed.
I maintain trails in the Sawtooth Wilderness Area and use your snowboard true bar to check for kinks, bumps, and bends in the blade of my crosscut hand saws, which must be perfectly straight to glide swiftly through the saw kerf with a minimum of resistance. Sawing with a well-tuned saw is as elegant a pleasure as skiing on well-tuned skis.
-C. Jay Dorr, Hailey, ID
WHERE HAVE ALL THE SKI GROOVES GONE?
Only a few alpine or telemark skis are still made with a center groove down the base. Most manufacturers claim it's unnecessary for recreational skiing and most racing...unless you ski at extremely high speeds when it helps a ski track better.
Find a tuning system that you are comfortable with. Create one through the advice of people who have respectable results, write it down, and follow it every time you work your bases and edges. Consistency and repetition are the key factors in World Cup tuning.
-Paul Guimond, Salomon Serviceman for Melanie Turgeon
GETTIN' A GOOD SHOP TUNE
If you take your gear to a shop for tuning, check out the quality of their work by asking to see other examples of their work...like on a recently tuned demo ski or snowboard. Check the edges with your fingernails to see how well it's been filed, deburred, and polished; ask how much the base and side edges were beveled (and why); check the base with a true bar to see if it's been stoneground flat, and if the structure is clean and crisp (with no p-tex hairs visible). The shop tech should also ask you questions...such as where and how well you ski or ride to determine the best tune, and also inspect your ski or board to diagnose and suggest appropriate repairs. If you don't like what you see or hear, go to another shop, or better yet, do your own work at home and get the tune you deserve.
I have begun to notice areas of oxidation on my ski bases, usually along the edges. I know I have probably not been waxing enough to prevent this. But I also can't convince myself as a beginning tuner to scrape the oxidized p-tex away with a steel scraper, since the bases are already flat in these areas. Other than a pricey shop stonegrind, do you have any suggestions?
-Greg Still, Radford, VA
Sure, there's several home remedies you can try. A light sanding with sandpaper and a sanding block will do the job, but it takes longest and also creates lotsa unwanted p-tex hairs. A steel scraper with a sharply burnished edge can be used with very light pressure to carefully shave the oxidized surface away. TheSkiVisions Base Flattener with a fresh structure stone in it will also do a good job.
Snowboard cores are usually made from wood...about one square foot (1 foot x 1 foot x 1 foot) of it, in fact, including waste material. It provides about 25% of the board's structural integrity, with the fiberglass wrap and topsheet providing 70-75%. Usually the wood core is made of one or more types of wood with varying degrees of hardness laminated together. These laminates can be as few as 10 veneer layers, or up to 80. The strength of the board is found in the glue of the veneers, which is usually a wood glue. Some manufacturers use soft woods in the middle and harder woods elsewhere...while others use a medium hardness wood for the entire core. An example of a softwood is aspen; maple and pine are hardwoods; poplar and spruce are medium. Hardwoods usually come from older-growth forests, while medium or softwoods come from younger forests.