How much base removal is too much?

[chilehed]

I’ve been trying to get my 2014 Head Rev 85 Pros set to a 1/2 degree base, but can’t seem to get any shops around here to do it - looks like they give it a couple of passes on the grinder and use whatever base guide is handy. This time I said “just grind the base until the edges are flat”, and the guy says “how many passes do you want?” Ummmm…. as many as it takes? How much does each pass take off? He ended up saying he'd give them eight passes, and seemed to think I was being unreasonable.

When I got them home I found that my 1/2 degree guide still removes material on the base 1/4” in from the edge. So, is there some reason other than laziness that no one will grind them as much as I want? It’s only about 1/64” that needs to be removed, so I have a hard time thinking that it would harm the skis… am I wrong? How far you can go without compromising things?

BTW, I'm limited in my ability to get firm with this particular guy (reasons I won't get into here).

 

[Steve]

Find another shop. A competent tech knows what a base bevel is and can set the machine accordingly.

When I go to get a grind I tell them what I want by degree and they do it.

 

[AmyPJ]

 

[Doug Briggs]

Go to another shop.

We regularly flatten bases to the point where we can get a .5 base bevel. It is a matter of grinding that bases, checking the height of the base relative to the edge and removing a bit of edge as you go so that your edges aren't marring the stone. It isn't a trivial process as it requires visual inspection as well knowledge (and ability) of how to measure base bevels. It isn't rocket science either.

It can't easily be done with a belt as a belt typically will result in a 1 base bevel since the belt and its drive wheel are relatively soft (compared to the stone). As you belt sand the ski to remove the base, you are taking away edge once you approach a base level that is close to the edge.

 

[DanoT]

I am not an expert so someone correct me if I am incorrect, but a base grind means stone ground and is not the same as as sharpening a ski as that is done on a edging machine (or by hand).

I just got a stone grind on a new pair of skis and the ski tech convinced me to have this done because he said that the amount of material removed is minimal and the end result is a structured base that takes wax better than a non ground ski base.

The ski tech also said that first he wants to sharpen the base edge (on a ceramic disc edge sharpener) because if the ski is base edge high it will damage the stone grinder. I told him to do 1* base edge and leave the side edge untouched.

 

[Doug Briggs]

@DanoT, you are correct. The stone grind does not sharpen the edges. It damages them (structures them) if they come into contact with the stone. The edges can also damage the stone.

If someone asks for a 'grind only' I ask them what bevels they are intending to apply to the edges. If they say a .5, I'll let them know that I can put a .5 on them at the same time as I do the grind, but that I can't give them any less than that or I'll damage their edges and my stone. I explain as in my previous post that I have to manage the edges while I grind the bases. If they are going to do anything more than a .5 I'll let them know that the skis will come with a .5 and a structured base. They are free to set the bevels higher.

 

[KingGrump]

When I got them home I found that my 1/2 degree guide still removes material on the base 1/4” in from the edge.

Your steel base edge is wider that 1/4"?

 

[Doug Briggs]

Your steel base edge is wider that 1/4"?

I think what he is saying is that his file touches base material 1/4" in from the edge. Whether that is from the outside edge of the ski or the inside edge of the base edge doesn't matter much. 1/4" is over 6 mm. The widest edge I found in my skis was 1.5 mm. I doubt any ski edges are wider than 2mm.

So best case is he is creating a bevel that impacts at least 4 mm of his base. I think this was called a 'wide bevel' in another discussion. A would say that 6mm wide bevel is excessive and not desirable.

 

[KingGrump]

I think what he is saying is that his file touches base material 1/4" in from the edge. Whether that is from the outside edge of the ski or the inside edge of the base edge doesn't matter much. 1/4" is over 6 mm. The widest edge I found in my skis was 1.5 mm. I doubt any ski edges are wider than 2mm.

So best case is he is creating a bevel that impacts at least 4 mm of his base. I think this was called a 'wide bevel' in another discussion. A would say that 6mm wide bevel is excessive and not desirable.

That's what I thought. But I can only go by what he wrote.
a 6mm wide base bevel in my book is call a rocker. Side to side rocker.

 

[chilehed]

I think what he is saying is that his file touches base material 1/4" in from the edge.

This. I thought I was pretty clear.

I've used three or four different shops over the years, told them exactly what I want every time, and never get it. I'm finally tired of it enough to do without them long enough to get them done right. I'll have a long talk with the owner of a different shop.

Thanks everyone for your input. Especially you, Doug.

 

[Doug Briggs]

You are welcome.

Executive summary: to reduce the base bevel (from 1 to .5, for example) requires base removal AND edge removal before you can actually get to a point where you can set the base bevel properly.

 

[AmyPJ]

This. I thought I was pretty clear.

I've used three or four different shops over the years, told them exactly what I want every time, and never get it. I'm finally tired of it enough to do without them long enough to get them done right. I'll have a long talk with the owner of a different shop.

Thanks everyone for your input. Especially you, Doug.

You would be wise to talk to the head ski tech at whatever shop, then make sure that person is the ONLY person who tunes your skis.

 

[Dakine]

Racers will often run the base bevel several mm into the ptex to get the edges up off the snow when running straight.
Of course, this makes the skis squirrely as you try to engage the edge but if gliding is important in a race a good skier can live with that.
Doug is right about relieving the edges before a quality grind to prevent stone damage and structured edges.
It is impossible to grind two materials of greatly differing hardness flat because the softer material compresses and rebounds much more than the harder one under the pressure of the stone.
Relieving the base edges before a grind is a technique that few grinder monkeys know and it is very time consuming.
Beware grinder monkeys....

 

[RuleMiHa]

This. I thought I was pretty clear.

I've used three or four different shops over the years, told them exactly what I want every time, and never get it. I'm finally tired of it enough to do without them long enough to get them done right. I'll have a long talk with the owner of a different shop.

Thanks everyone for your input. Especially you, Doug.

I just drove an hour and forty-five minutes to get to a shop that I trusted to give me the edges I asked for. Hmph!

 

[BGreen]

I can put a .5 on them at the same time as I do the grind, but that I can't give them any less than that or I'll damage their edges and my stone

Is this still true with the Scout? I was under the impression you could go to .2 or .3.

 

[AmyPJ]

Racers will often run the base bevel several mm into the ptex to get the edges up off the snow when running straight.
Of course, this makes the skis squirrely as you try to engage the edge but if gliding is important in a race a good skier can live with that.
Doug is right about relieving the edges before a quality grind to prevent stone damage and structured edges.
It is impossible to grind two materials of greatly differing hardness flat because the softer material compresses and rebounds much more than the harder one under the pressure of the stone.
Relieving the base edges before a grind is a technique that few grinder monkeys know and it is very time consuming.
Beware grinder monkeys....

Standard procedure at the shop I use. I saw some structured edges coming out of another shop last season, and Makes for an interesting ride down the hill, for sure.

 

[BGreen]

Racers will often run the base bevel several mm into the ptex to get the edges up off the snow when running straight.

Are you sure that’s not just an unfortunate side effect of a trimjet?

 

[Doug Briggs]

Is this still true with the Scout? I was under the impression you could go to .2 or .3.

The scout goes to .5. I could manually 'recalibrate' the machine to get a .2, but that is a laborious process and basically redefines all stated bevels by .3.

It is possible to avoid the base bevel into the P-Tex with the TrimJet and the Scout but it takes a lot more care than just setting the bevel adjustment and pressing start. As mentioned in other threads, the operator is ultimately responsible for the quality of the tune.

I know that speed skiers will round there edges to prevent them grabbing. Some will leave a bit of sharper edge under the foot for safety at the start. I haven't heard of providing base bevel into the P-Tex, but it makes sense that it would make a ski faster by keeping the steel off the snow. Just how desirable that would be over quicker edge engagement would remain to be determined, I suppose.

 

[Dakine]

Are you sure that’s not just an unfortunate side effect of a trimjet?

No, it is a secret so don't tell anybody.
Banana skis are very fast, if you can ride them.
"Base is fast and steel is slow"...from a very good tech.

 

[Doug Briggs]

Racers will often run the base bevel several mm into the ptex to get the edges up off the snow when running straight.
Of course, this makes the skis squirrely as you try to engage the edge but if gliding is important in a race a good skier can live with that.
Doug is right about relieving the edges before a quality grind to prevent stone damage and structured edges.
It is impossible to grind two materials of greatly differing hardness flat because the softer material compresses and rebounds much more than the harder one under the pressure of the stone.
Relieving the base edges before a grind is a technique that few grinder monkeys know and it is very time consuming.
Beware grinder monkeys....

No, it is a secret so don't tell anybody.
Banana skis are very fast, if you can ride them.
"Base is fast and steel is slow"...from a very good tech.

That is why speed skis usually have a higher base bevel than tech skis.