Thread: Repetitive cutting in a ski base

Pattern base skis allow you to get both some push and glide Ian. The pattern has the same function as short skins ('kickers') and klister (soft wax that both grips and doesn't). They're the norm for Australian touring where the typical terrain is rolling hills and the typical snow is wet/firm/granular.

They evolved out of the long skinny skis that these days are often called Nordic. There are other differences cp downhill/ski mountaineering/alpine touring skis that I won't bore you with although there's been a convergence in length, width and side-cut.

Several of the usual ski makers produce them with all sorts of variation in the pattern. Once even mica was inserted in the base for the purpose!

You wax the pattern by applying liquid wax and buffing while hot waxing the tip and tail. Edge tuning is harder; in some designs you have to sacrifice some plastic.

The skis I'm modding are fairly standard all mountain skis, chosen for lift-serviced telemarking and for short jaunts into neighbouring terrain to descend some wildsnow slopes. I want to climb gradients up to 10-15 degrees without stopping to put skins on.

I know about pattern base Nordic skis, and many many years ago owned a pair of mica base skis -- which were prone to balling up in Australian snow conditions. I'm not as familiar with [grip] waxed skis -- but my son races Nordic so in the house I have a nearly complete collection of grip waxes and klister. Plus a thermometer to help select the most appropriate wax or klister for the conditions.

What concerns me with your approach is that you appear to want to cut a pattern into the whole length of the ski, rather than just the kick zone.
and more importantly, having cut the pattern, I can't see how you will be able to polish the insides of the crescents so that the ski glides rather than grips when going down hill.

When I'm being particularly keen, I'll use a spray wax on the grip zone to improve the glide of my pattern bases. My son thinks it's a bit of overkill, but then he can't talk. Race prepping a pair of his race skis can use more than $30 of wax. And a for major race I might prep two or three pairs.

Ah, you know the tech. And you're in the right country.

The factory patterns that I have tend towards half the ski length with the centrepoint offset to the rear of the balance point.

My model custom patterned ski has about a third of PB and I won't be going longer than that to begin with. (That's an old Karhu XCD Supreme that I started telemark on).

We're having a stunning season this winter. Falls Creek snow depth might hit 2 m this week. Heading back to Mt Beauty for another two weeks shortly.

In this sense the ski's balance point is less relevant than the ski's flex and the location of the wax [grip] pocket.

I'm fairly certain that no one in AUS has a ski flex testing machine and I'd hazard that there's no more than two or three of the simpler steel testing plates.

Enjoy the spring snow -- coming off the Paralyser should be awesome this week.

Indeed. Though these don't really have wax pockets nor much camber overall. Another variable is the ratio of voids (the pattern) to solids. As a negative pattern it only works when the base is pressed into the snow. There has to be enough voids to allow that to happen but not so many that the weight isn't supported during the glide. Clearly snow condition will play a large role in this. It's interesting to observe that Fischer and Madshus seem to have moved away from -ve pattern bases for their touring skis.

So it's just as well I can start light and extend the pattern if necessary, and keep kicker skins in the pocket while out testing.

Perhaps I ought to look for some R&D funding for this!

Well it's been bucketing down again this week.

Here's a couple of pics from earlier to provoke your nostalgia perhaps.

Mackay.jpgThe Spurs under snow from Mackay.jpg

I won't claim to know Falls Creek and Mt Bogong very well -- I've only skied there a few times, but if you're looking to do away with climbing skins I think you are on a hiding to nothing.

To get the most out of a Nordic ski requires a particular gait when skiing. A gait I've never seen replicated by a person using skins or telemark skis. In part I think it's a function of the wider ski, the type of binding and the boot used. When a Nordic ski is evenly weighted the grip zone is mostly not in contact with the snow and the ski glides.

With a telemark ski -- which has a lot less flex than a nordic ski -- the ability for the grip zone to glide is even more important. Hence the popularity of skins.

I wish you luck with your experiments.

We just cut them with a small angle grinder. Worked fine.

Originally Posted by rustynail

We just cut them with a small angle grinder. Worked fine.

Yeah, some folk have used dremels for a fine pattern.

Thanks Ian.

The application was mentioned in post 17. Steeper than that I'll select one of the normal methods.

These skis aren't for touring so diagonal stride isn't one of the priorities.

The trend in PB skis has been to wider, shorter, curvier and less cambered. In other words to optimise turning. Diagonal stride with these skis is no fun. It is nonetheless possible as indeed it is with the waxing base equivalent when fitted with kicker skins.

There are very few telemark specific skis on the market these days. People typically go for an all-mountain ski with the degree of dampness and the turning radius that will work in their applications.

Here in Canada, I think I'm seeing mostly skins on the serious back country skiers.
Can't say I've seen any pattern bases, but then again I haven't really been looking. My interests are currently with regular down hills and nordic skis for groomed trails.

You don't see PBs in NZ either. My first guide over there was gobsmacked at mine. But that's their terrain. Long pitches mean the skins transition overhead is minor. There are parts of Oz that are similar. But on the plains PBs make sense.

So I'm not really any forrarder on the question of even spacing up the length.

The idea of string and coils met with deafening silence

Since the project now can't be finished for the next trip up there's time available at the end of season. I'm now thinking of a strip of alloy with evenly drilled holes. One end attached to the baseplate, the other with each hole in turn dropped onto a pin clamped to the base up the ski.

How to do the drilling? There is a drill press so maybe drill hole 1, put a pin in it and appropriate width packing beside that to butt against the stationary drill bit. And repeat.

Originally Posted by rsser

You don't see PBs in NZ either. My first guide over there was gobsmacked at mine. But that's their terrain. Long pitches mean the skins transition overhead is minor. There are parts of Oz that are similar. But on the plains PBs make sense.

In an earlier post you mentioned using your patterned bases on grades of 10 to 15 degrees -- a quick bit of trig says that those sorts of grade are equivalent to slopes of 15 to 25%. 25% is one hell of a pitch somewhat beyond the upper end of the maximum grade found on an Olympic standard Nordic ski course. At 15% even the best in the world have typically stopped diagonal striding and are herringboning.

So, I'll repeat my suggestion that you might be on a hiding to nothing

Thanks for the outstanding help.