Changing Camber

[Dr. Delam]

I have had a couple pair of skis where the camber did not come out exactly as planned. I decided to do a little experiment to see if I could permanently change the camber of the skis and it worked.

I just stuck the skis back in the press and heated them up for an hour. I took them out and did some creative clamping and blocking on the work bench and let them sit overnight to cool. The tricky part is figuring out how much blocking you need to do to achieve the final results. I did a test on some junk skis to get an idea of how much change I would get.

I don't know about the long term effects of doing this to a pair of skis but so far they have been holding up fine and the skis are performing much better.

Anybody else try this?

[chrismp]

great idea! what epoxy are you using and how much did you heat the press?

[MontuckyMadman]

We pull hot and tweek with weight straight away tk get desired results. Post cure takes a few days.

[knightsofnii]

i dont know about changing camber, but i've definitely taken boards pressed in xx running length mold, and repressed them in yyy running length mold... and that also worked great

[gerryrig]

Just found this thread. I have this same problem. I have a pair of skis I pressed a few weeks back that came out with too much camber. The skis have about 9mm of camber in them right now and I would like to bring it down to ~4mm. Do I need to over flex them to achieve this?

[Dr. Delam]

I have always used QCM epoxy and I set the temp at 200 F for recooking. I normally press at 180 but I figured a little hotter would be ok.

Gerryrig, it is hard to say how much you will need to tweek them to reduce the camber x amount. You might just want to press them flat and if you need to go further then reheat and decamber them.

Like MM says, it is best to make adjustments in the post cure time frame. The problem is that I don't always know what I want until I ski it!

Next I am going to try and raise the tip height on a pair of skis that came out much lower than anticipated. I am thinking that is going to be harder since my cores are quite stiff and extend into the tip rise.

[knightsofnii]

yes, when repressing do it at around 200 deg, gets everything softer.

I've only ever taken a board that i didn't like where the bend points started, and stuck it into a smaller mold... I dont think it's possible to do the opposite and unbend tips.

But if you're going for more tip curve you should be able to make that happen, i hope. Dont expect any dramatic changes though, the materials will still have some memory

[knightsofnii]

and i think in tips you're going to create some extra shear stress as you change the bend, possibly even fractures, with ski tip radii i dont know how that will end up, good luck!

[Dr. Delam]

Tip modification was a success. I was able to add 2 cm to the tip height to bring it up to 7 cm. I don't think I would have wanted to try for more for fear of cracking the core.

Now these will be more confidence inspiring as I think 5 cm tip height is too low for off piste skiing in variable snow.

[vinman]

I like this DD. I may try this with a set of mine that I feel has a low tip rise. If this is successful The set Im thinking of will be even better. Thanks

[knightsofnii]

i wonder if you used an unbroken 80grit, or even a 60grit belt if they make it, with autofeed grinder, if you could just sand off a topsheet by sticking it thru the grinder upsidedown?

[Dr. Delam]

Vin, I don't do full wrap edges in the tips so this probably helped. You are doing full wrap, correct?

I also found that most of the new tip rise came in the area of the tip spacer and the core stayed mostly the same. I cut my cores straight across.

I say give it a go and see what happens. Once the ski is heated up you should be able to get a feel for how much you can bend the sucker.

[PTTR]

I tried it on a pair that used to have flat camber with great result. Have had a couple of hours on snow and they seem to keep up. This is so cool! I wonder how many times you can do this.
thinking..
...portable press-changing skis/boards with the weather!...

I put some extra shims in the camber and pressed the skis for 1 hour. same heat as first press and pulled them out. no postcure blocks. the skis are glued with entropy.

[vinman]

I just repressed a pair that came out with less camber than expected. I recently recut my camber mold and was unhappy with the result. These skis came out with effectively flat due to my mistake cutting the mold. I quickly recut the mold again with more camber (4mm over the central 1/3 of the mold ~140 cm). This took a couple hours and then I repressed the pair with 200 F on bottom 160 F on top for 45 min. I took them out hot and clamped the tip and tail to the table with a 22x22 mm block of ash under the waist and left them overnight.

The result was 5mm of camber each (10mm between them at the waist). I've flexed them several times now and the camber remains steady.

I am using entropy resin currently. I think that getting this done within the post cure time while the epoxy was not 100% cured was the key. We will see how they hold up on snow this winter.

[MadRussian]

then I repressed the pair with 200 F on bottom 160 F on top for 45 min. I took them out hot and clamped the tip and tail to the table with a 22x22 mm block of ash under the waist and left them overnight.

I wonder how accurate your temperature reading? My understanding at 200° F p-tex will softened substantially if not melts. Especially around the edges.

I use that method to create camber on my first pair 1" block create 5" camber. Well I forgot to check Camber every Ski day remembered about 10 days on them.... camber was zero (my mold zero camber mold)