Making a ski more convex or more concave is the exact opposite of what a grind is supposed to do isn't it? Call me crazy and obsolete, but I don't recall so many "shop made my skis unskiable" stories back when everything was ground on belts. True that skis were different and a grab didn't throw you off your feet on a straight ski... but also didn't hear many instances of skis not being flat after being ground.
I don't think I'll be taking my skis to be ground EVER until the technology changes again.
It's the people using the technology. Honestly, i'd rather have someone do the skis with a small stone grinder who really knows what they're doing and how it should come out, then someone with a huge machine who never checks it. The strange thing is, we're talking really small amounts and yet it makes a huge difference. If you have concavity of 1/16th inch that's enough for a horrible day.
As far as the belt sander days......maybe someone who used to tune skis in those days will chime in. My sense is that most skis of that era, other than racers, were fairly atrociously tuned. Let's not forget they were straight and skinny and long and one didn't carve arcs at 10mph just by tipping them on edge.
How many people even checked their skis for flatness then? Even now it's rare.
I know as a kid my attempts at tuning were total butchery. Yet I went out with those disasters and did just fine. But I didn't know any better.
Just piling on here out of solidarity and disappointment. After the Utah gathering my skis were trashed from hitting a lot of rocks. They needed a grind. I only had five workdays before my next trip. Meanwhile my favorite shop is a 3 hour round trip from my house, and there was no way I was going to be able to fit in two of those on top of everything else I needed to get done. So I took the skis to a local shop I don't know well, and they butchered them. Among other things, there is a clearly visible (and feelable) 3cm wide stripe down the right-hand 1/3 of each ski where the "structure" (if you can call it that) is totally different from the structure on the rest of the ski - much coarser and more irregular. I did not see this when I first picked them up, partly because they left so much damn wax on the skis. Noticed it only when I when to brush them out the night before my trip, at which point it was too late. Took them back after I'd skied on them a few times. At first the shop manager had trouble - or pretended to have trouble - seeing what I was talking about. He said he would be happy to re-do them. I said, "I don't want you to re-do them - and take yet MORE material off my skis - before I'm sure we agree about exactly what the issue is." I happened to have another pair of skis in my car with a good tune from Edgewise. Brought them in and put them under the light next to the ones they had tuned and he grudgingly admitted that there was something to what I was saying. At first tried to tell me that it was because of having been skied on. (Which is why there is a perfect swath of extra-coarse texture down the right-hand side of BOTH skis, right?) Then he started a sentence which began "Well, I know Kastles are really nice skis, but sometimes even with high end brands there can be issues with the base material..." He trailed off when he saw my look of incredulity. Finally he admitted that if I was expecting a "really fancy tune" (his words, not mine), I might want to stick with a shop that specialized in those. Sheesh. Come on. We're talking basics here.
Have never had a bad grind from Edgewise. Even back when Graham had a very small stone grinder and he was downtown in Stowe or in the base of the Skiershop ? store. That's the place I used to drive hours for. He's fixed a number of horror stories in the past. One of the rare places it makes sense to ship skis to.