Beveling Edges on a Variably Concave Base

[Cork7 Belly Flop]

I have a pair of skis whose bases are flat ~1 cm from the edges, but concave through the middle (moreso at the tips/tails). I want to start adding extra base bevel to the tips/tails but the dip in the middle of the base is screwing up the angle of the guide.

Does anyone here have a workaround they use for their skis? I was thinking of creating a "shim" by putting painter's tape down the middle, then adding some kind of material over it (not sure what yet), then sanding it down with a truebar until it's even with the edges across the whole area to be beveled. Or would it be better to use wax for this purpose (scrape only until wax is gone from edge area)?

 

[silverback]

Unless this is a water ski I think you need to have them ground flat first.

 

[GregK]

Definitely get them stone ground flat first before doing any tuning for the best results.

 

[Cork7 Belly Flop]

Grinding them all the way flat will remove way to much material from the base (I had to get them ground for the flatness around the edges).

 

[KingGrump]

Got a pic of the ski base with a true bar across?

 

[GregK]

Grinding them all the way flat will remove way to much material from the base (I had to get them ground for the flatness around the edges).

Are these brand new skis? If they are that far off, I’d be complaining to the manufacturer.

Any idea how many passes did they already? Fully automated machine or a semi automatic machine?

 

[Jacques]

I have a pair of skis whose bases are flat ~1 cm from the edges, but concave through the middle (moreso at the tips/tails). I want to start adding extra base bevel to the tips/tails but the dip in the middle of the base is screwing up the angle of the guide.

Does anyone here have a workaround they use for their skis? I was thinking of creating a "shim" by putting painter's tape down the middle, then adding some kind of material over it (not sure what yet), then sanding it down with a truebar until it's even with the edges across the whole area to be beveled. Or would it be better to use wax for this purpose (scrape only until wax is gone from edge area)?

I would not worry too much about it. Just do the bevel work.
Some guides cover more of the base than others.