It is impossible to get a flat interface between two materials with differing moduli of elasticity with a grinding operation.
This is because the wheel puts a downward force on the base to make it cut and the materials spring back to differing degrees.
By using multiple light passes you can come close.
When things really have to be flat it takes a skiving (cutting) operation.
Precision machine tools have their ways hand scraped to eliminate high spots and get them flat within a few wavelengths of light.
Skis wouldn't ski differently if they were that flat.
As @Jacques can attest, the way to true flatness is by using a sharp steel scraper after the skis have been "flattened" structured.
Not many folks have the skill or patience to do this.
Certainly not me and I'm not rabid about really flat skis anyway.
I do run a steel scraper down the ski before waxing to find out just how base high they are and where.
According to @Primoz, even World Cup techs aren't this crazy about ski flatness.
Snow and ice are not flat either so good enough is good enough.
Yes, as I state in a few of my videos, I too do not care about a ski being perfectly flat!
Reasonably flat is good.
It's easy to flatten out a convex base, but near impossible to flatten a convex base with a steel scraper.
There are a few really fancy steel scrapers out there somewhere that will cut even steel. I have never had one, so don't know for sure.
The SkiVisions deal has a steel bar along with the stones, so maybe.
A Ski Vision with a burred cutter is a wicked beast.
Not for amateurs.
Oh darn it! I said convex twice! In the second time I meant to say CONCAVE! My bad! Hard to flatten concave with a scraper!Yes, as I state in a few of my videos, I too do not care about a ski being perfectly flat!
Reasonably flat is good.
It's easy to flatten out a convex base, but near impossible to flatten a convex base with a steel scraper.
There are a few really fancy steel scrapers out there somewhere that will cut even steel. I have never had one, so don't know for sure.
The SkiVisions deal has a steel bar along with the stones, so maybe.
I fixed it.Oh darn it! I said convex twice! In the second time I meant to say CONCAVE! My bad! Hard to flatten concave with a scraper!
I was too late coming back to edit.
I square up the bar by working it through a series of wet sandpaper grits on a piece of glass till the edge is sharp.What's your technique for burring the Ski Vision steel bar?
I square up the bar by working it through a series of wet sandpaper grits on a piece of glass till the edge is sharp.
Then I burr it by clamping it in a vice and running a piece of carbide rod down the length at a 45 degree angle (usually) with heavy pressure.
You won't believe how a properly burred edge will cut.
I have a carbide rod I run my steel scrapers down after sharpening them on a file mounted in a vice.
Never thought of putting a burr on my Ski Visions bar, thanks!
How do you maintain the stones?
I don't use the stones.
A good operator on a Winterstiger is much better for that.
But, if you take your skis in flat and get a grind that is only as wide as the waist of the ski and then file and hone, that's the best an amateur can do.