Modify/stiffen your own skis?

On Apr 1, 5:14*pm, wrote:
I would think if you wanted to soften a ski functionally, you could
broaden the flex range in the middle toward the tip and tail by some
careful scraping.

rm


The bigger question nobody asked is why screw around with a ski that
doesn't fit by adding material etc while not knowing what they are
doing. Srew up the ski than you can't give it away. Why not just get
a new ski that fits?

On Apr 2, 12:37 am, wrote:
On Apr 1, 5:14 pm, wrote:

I would think if you wanted to soften a ski functionally, you could
broaden the flex range in the middle toward the tip and tail by some
careful scraping.

rm

The bigger question nobody asked is why screw around with a ski that
doesn't fit by adding material etc while not knowing what they are
doing. Srew up the ski than you can't give it away. Why not just get
a new ski that fits?

Wahhl, for those with experience and who have done some testing, why
not? There are lots of old skis to experiment with. Most elite
hobbyists customize their stuff. Skiers are the few I've seen who
don't usually monkey with their stuff. The base doesn't affect
stiffness, I don't think. So, sure they wax and grind the base, but
one might find that with a bit of testing that FOR FREE you can
TOTALLY DIAL IN your skis to be just the way you want them. Trial and
error will surely tell you more than off the shelf squeezes and
measurements can---altho I suppose some shops can give you lots more
data than others---do you always know what that data will mean on the
snow?? I mean, you could get it wrong somewhere---so why not learn how
to adjust it after you get home? Just because some skiers are not
handy doesn't mean they all aren't. And just because some skiers don't
really know what they like in a ski doesn't mean others don't. Anyway:
thin carbon or glass and a very thin coat of epoxy just might give you
stiffness where you want it. Why not try to learn about such things?
Offhand I think that skis are thin and weak enough as it is that I
don't presume to guess how one might effectively and safely SOFTEN
flex somewhere. Maybe one could sand away some of that surface 1mm and
replace it with an equally strong epoxy which is flexible. --JP

On Apr 2, 9:59 am, jeff potter wrote:
On Apr 2, 12:37 am, wrote:

On Apr 1, 5:14 pm, wrote:

I would think if you wanted to soften a ski functionally, you could
broaden the flex range in the middle toward the tip and tail by some
careful scraping.

rm

The bigger question nobody asked is why screw around with a ski that
doesn't fit by adding material etc while not knowing what they are
doing. Srew up the ski than you can't give it away. Why not just get
a new ski that fits?

Wahhl, for those with experience and who have done some testing, why
not? There are lots of old skis to experiment with. Most elite
hobbyists customize their stuff. Skiers are the few I've seen who
don't usually monkey with their stuff. The base doesn't affect
stiffness, I don't think. So, sure they wax and grind the base, but
one might find that with a bit of testing that FOR FREE you can
TOTALLY DIAL IN your skis to be just the way you want them. Trial and
error will surely tell you more than off the shelf squeezes and
measurements can---altho I suppose some shops can give you lots more
data than others---do you always know what that data will mean on the
snow?? I mean, you could get it wrong somewhere---so why not learn how
to adjust it after you get home? Just because some skiers are not
handy doesn't mean they all aren't. And just because some skiers don't
really know what they like in a ski doesn't mean others don't. Anyway:
thin carbon or glass and a very thin coat of epoxy just might give you
stiffness where you want it. Why not try to learn about such things?
Offhand I think that skis are thin and weak enough as it is that I
don't presume to guess how one might effectively and safely SOFTEN
flex somewhere. Maybe one could sand away some of that surface 1mm and
replace it with an equally strong epoxy which is flexible. --JP

Fair enough, but why not start from scratch? A mold for a nordic ski
isn't going to be too terribly hard to build, and while optimizing the
composite layup isn't trivial it isn't really hard either.

On Apr 6, 2:03*pm, wrote:
On Apr 2, 9:59 am, jeff potter wrote:





On Apr 2, 12:37 am, wrote:

On Apr 1, 5:14 pm, wrote:

I would think if you wanted to soften a ski functionally, you could
broaden the flex range in the middle toward the tip and tail by some
careful scraping.

rm

The bigger question nobody asked is why screw around with a ski that
doesn't fit by adding material etc while not knowing what they are
doing. *Srew up the ski than you can't give it away. *Why not just get
a new ski that fits?

Wahhl, for those with experience and who have done some testing, why
not? There are lots of old skis to experiment with. Most elite
hobbyists customize their stuff. Skiers are the few I've seen who
don't usually monkey with their stuff. The base doesn't affect
stiffness, I don't think. So, sure they wax and grind the base, but
one might find that with a bit of testing that FOR FREE you can
TOTALLY DIAL IN your skis to be just the way you want them. Trial and
error will surely tell you more than off the shelf squeezes and
measurements can---altho I suppose some shops can give you lots more
data than others---do you always know what that data will mean on the
snow?? I mean, you could get it wrong somewhere---so why not learn how
to adjust it after you get home? Just because some skiers are not
handy doesn't mean they all aren't. And just because some skiers don't
really know what they like in a ski doesn't mean others don't. Anyway:
thin carbon or glass and a very thin coat of epoxy just might give you
stiffness where you want it. Why not try to learn about such things?
Offhand I think that skis are thin and weak enough as it is that I
don't presume to guess how one might effectively and safely SOFTEN
flex somewhere. Maybe one could sand away some of that surface 1mm and
replace it with an equally strong epoxy which is flexible. --JP

Fair enough, but why not start from scratch? *A mold for a nordic ski
isn't going to be too terribly hard to build, and while optimizing the
composite layup isn't trivial it isn't really hard either.- Hide quoted text -

- Show quoted text -

Well, starting the production work from scratch, building the mold and
doing the composite layup, may not be too hard, starting from scratch
means having to run a bunch of finite element simulations with a range
of elastic and inelastic foundation boundary conditions to simulate
the multitude of snow conditions.

That said, I guess Jeff would likely use a trial and error
experimental appoach to avoid running mathematical model simulations.

On Apr 6, 8:28 pm, wrote:
On Apr 6, 2:03 pm, wrote:



On Apr 2, 9:59 am, jeff potter wrote:

On Apr 2, 12:37 am, wrote:

On Apr 1, 5:14 pm, wrote:

I would think if you wanted to soften a ski functionally, you could
broaden the flex range in the middle toward the tip and tail by some
careful scraping.

rm

The bigger question nobody asked is why screw around with a ski that
doesn't fit by adding material etc while not knowing what they are
doing. Srew up the ski than you can't give it away. Why not just get
a new ski that fits?

Wahhl, for those with experience and who have done some testing, why
not? There are lots of old skis to experiment with. Most elite
hobbyists customize their stuff. Skiers are the few I've seen who
don't usually monkey with their stuff. The base doesn't affect
stiffness, I don't think. So, sure they wax and grind the base, but
one might find that with a bit of testing that FOR FREE you can
TOTALLY DIAL IN your skis to be just the way you want them. Trial and
error will surely tell you more than off the shelf squeezes and
measurements can---altho I suppose some shops can give you lots more
data than others---do you always know what that data will mean on the
snow?? I mean, you could get it wrong somewhere---so why not learn how
to adjust it after you get home? Just because some skiers are not
handy doesn't mean they all aren't. And just because some skiers don't
really know what they like in a ski doesn't mean others don't. Anyway:
thin carbon or glass and a very thin coat of epoxy just might give you
stiffness where you want it. Why not try to learn about such things?
Offhand I think that skis are thin and weak enough as it is that I
don't presume to guess how one might effectively and safely SOFTEN
flex somewhere. Maybe one could sand away some of that surface 1mm and
replace it with an equally strong epoxy which is flexible. --JP

Fair enough, but why not start from scratch? A mold for a nordic ski
isn't going to be too terribly hard to build, and while optimizing the
composite layup isn't trivial it isn't really hard either.- Hide quoted text -

- Show quoted text -

Well, starting the production work from scratch, building the mold and
doing the composite layup, may not be too hard, starting from scratch
means having to run a bunch of finite element simulations with a range
of elastic and inelastic foundation boundary conditions to simulate
the multitude of snow conditions.

That said, I guess Jeff would likely use a trial and error
experimental appoach to avoid running mathematical model simulations.

You could use FEA, although you don't really need to. The deformation
of the ski is easy to solve analytically. You would need an iterative
solver for the contact boundary condition, but even that's not very
hard. The only tricky part is setting discrete constraints for the
optimization script. A day or so of coding could save a year of trial
and error.

That's the hard way of doing the design. The easy way is to start
with the layup schedule for a ski that's close to what you want (it
helps if you know someone who's broken one) and go from there.

I've always thought that adjustable stiffness would be posible and a
good idea.
If someone is to start a new ski factory, think about it.

A mobile carbon upper layer and a rollover (or rollunder)
adjustement. More or less like a swimming pool jumping board.

On Apr 8, 2:35*pm, wrote:
I've always thought that adjustable stiffness would be posible and a
good idea.
If someone is to start a new ski factory, think about it.

A mobile carbon upper layer *and a rollover (or rollunder)
adjustement. More or less like a swimming pool jumping board.

Yup. Jeff may want to talk to the K2 engineers who were using
piezoelectric polymers to alter vibration characteristic of skis. By
feeding power into the piezoelectric material Jeff may be able to
change the ski's structural properties. I think that K2 was trying
the piezoelectric skis in the mid 1990s.

You guys are funny. I think I'll keep it simple. I'll add a thin layer
of carbon/glass to a test ski to see if it makes it any stiffer in a
good way. If it does then I'll have an easy way to make good skis even
better if they need a bit of extra stiffness somewhere. --JP

wrote:

: I've always thought that adjustable stiffness would be posible and a
: good idea.
: If someone is to start a new ski factory, think about it.

: A mobile carbon upper layer and a rollover (or rollunder)
: adjustement. More or less like a swimming pool jumping board.

If i remember well, fisher had a xc-ski with a knob on top to
adjust camber. That was in the 80's. There were ads in XC
magazines but i never tried those. Can't remember the product
name either.

When i finally find the courage to clean-up my appartment i'll
check if i can dig up one of those magazines before throwing them
out.

Sylvain

fauvel AT emt dot inrs dot ca

Originally Posted by Jeff Potter (of OutYourBackdoor.com)

You guys are funny. I think I'll keep it simple. I'll add a thin layer
of carbon/glass to a test ski to see if it makes it any stiffer in a
good way. If it does then I'll have an easy way to make good skis even
better if they need a bit of extra stiffness somewhere. --JP

Changing the stiffness of your ski is a great idea. Something like put a spacer between the bound up pair, then put the heat sensative ski in the hotbox to change it.
But putting layers on the top of your ski won't change the stiffness much at all. All the strength of your ski is in the bottom " tension" layer under the ptex.