Cassette idea

[skibum]

I apologize if this has been discussed already but I was hoping to avoid cores moving around during pressing. I was thinking of using a steel sheet instead of aluminum for the bottom sheet. Then once the base and edges are laid down the perimeter could be surrounded with a few (4-6 per ski or so) rare earth metal magnets (which would stick to the steel sheet). The magnets would then have enough height to keep the core from pushing side to side. I have read of people us steel instead of aluminum and assume with mold release it would function in a similar manner.

Any thoughts or opinions on this would be appreciated

Thanks

[falls]

Yep
Someone has done this.
Spring steel (I think) and rare earth magnets.
I think they used them to stop the core shifting rather than the base though. If you use them to stop the base moving and your core it means your core will have to be exactly the right size. This means any failure of your magnet system and the core shifts then the ski will be ruined.
You could use 2mm tall magnets for base alignment then taller ones for your core.

[ben_mtl]

Securing the base is super easy, I just use some spray glue (3M), a small patch at 1/3 and 2/3 of ski length, never had any problem. The bases won't move and it's not enough glue to make it harder to remove the finished ski from cassette. I even spray this glue after waxing the cassette and it works !

Limiting the movement of the core is another story though... I add some wood between my 2 cores and use locating pins on this added part. It's an extra 10min job but it works OK.

[skibum]

I actually was looking to keep the core stationary. I had read about the 3M spray glue for under the base. I was just hoping to avoid using locating pins if possible to keep the core stationary.
thanks guys

[doughboyshredder]

Limiting the movement of the core is another story though... I add some wood between my 2 cores and use locating pins on this added part. It's an extra 10min job but it works OK.

What a great idea. never thought of that. I am going to do this on the next board. I am going to glue little wood tabs to the outside of my sidewalls, and have the locating pins outside of the layup.

Sweet!

[skidesmond]

Limiting the movement of the core is another story though... I add some wood between my 2 cores and use locating pins on this added part. It's an extra 10min job but it works OK.

What a great idea. never thought of that. I am going to do this on the next board. I am going to glue little wood tabs to the outside of my sidewalls, and have the locating pins outside of the layup.

Sweet!

Do you mean like this: http://www.skibuilders.com/phpBB2/viewt ... tch+sticks

I'm going to do the same thing on my next set of skis.

[SRP]

I have tried the dowel through the core and the wood blocks on the outside. Both worked ok, although I think I liked the dowel through the core better. I already have the rare earth magnets in different thicknesses to try on the next lay up using a steel cassette. I plan on just coating all the magnets with mold release so thay can be used over again. I'll update after the next layup.

[doughboyshredder]

kind of like the matchstick idea, but a lot bigger tabs with holes for dowels that will be glued to the cassette.

Anything that impedes the expansion of the base during pressing can cause deformations.

Ask iggy about that one.

Good luck with the magnets. Remember magnets slide easily. They have very little shear hold. Getting them out of the cured resin is going to be quite fun also.

[MontuckyMadman]

kind of like the matchstick idea, but a lot bigger tabs with holes for dowels that will be glued to the cassette.

Anything that impedes the expansion of the base during pressing can cause deformations.

Ask iggy about that one.

Good luck with the magnets. Remember magnets slide easily. They have very little shear hold. Getting them out of the cured resin is going to be quite fun also.

What is the appropriate level for expansion inside the cassette? .75MM all the way around? Less?

The swell panik guy and the other frenchy from Richuks journal see virtually no room for expansion in the cassettes.

I cannot believe I have been putting holes in my cores all this time. Obviously outside the layup, duh. I was going to switch to the plastic standoffs next, cause they are much smaller but I just scrapped that idea.


How much deformation Igg?

[doughboyshredder]

kind of like the matchstick idea, but a lot bigger tabs with holes for dowels that will be glued to the cassette.

Anything that impedes the expansion of the base during pressing can cause deformations.

Ask iggy about that one.

Good luck with the magnets. Remember magnets slide easily. They have very little shear hold. Getting them out of the cured resin is going to be quite fun also.

What is the appropriate level for expansion inside the cassette? .75MM all the way around? Less?

The swell panik guy and the other frenchy from Richuks journal see virtually no room for expansion in the cassettes.

I cannot believe I have been putting holes in my cores all this time. Obviously outside the layup, duh. I was going to switch to the plastic standoffs next, cause they are much smaller but I just scrapped that idea.


How much deformation Igg?

I don't think it matters how much room you leave for expansion, as long as it is equal all along the metal edge. If it's not equal it will change the shape. Dramatically.

[OAC]

Cassette and pins @ 1:20
http://www.youtube.com/watch?v=TyE-1fKQ ... re=related

[Richuk]

0.5mm all the way round in my cassette - the 1 mm washer was only used once correctly set the width of the edges that extra 1 mm.

Initial photo's posted to show that a high degree of accuracy can be obtained at home - with a bit of work.

Tim pointed out that it could be a lack of pressure on the edge set that leads to wibbly wobbly edge set - could be. If so, then a really precise rebate is quite important for an even application of pressure.

If it turns about to be less than 0.5mm, I will follow 4frnt. If its any bigger I'll soon find out, as I will be skiing a new type of ski with aluminium bases : )

Anyway, I hope to find out pretty soon.

I used hot glue for keeping the base in place - pressing one at a time makes it less likely to break away. I understand a lot of people use spray adhesive with great results.

Bond the matches on before lay up - I'm always in a rush.

[falls]

It seems for the smaller makers eg. Moment, that the next step up is what they call "snap in" cassettes. I think these are like the one you see in the swell panik video. Basically the recessed area is exactly the size of the base + edges. You place the base in then the pre curved edge on one side then the edge on the other side. The second edge has to be "snapped" in, often with a roller, hence the name.
When the heat cones on the cassette edges and plastic all try and expand which creates a great edge fit as the edges and base are pushed together. Because there is the 50-90psi downward force of the core the base can't warp when heated and constrained width wise.
That's what it looks like to me.
Iggys cassettes look like he spray adhesives the base to the aluminium then has metal blocks riveted on that hold the core in alignment.

[doughboyshredder]

Cassette and pins @ 1:20
http://www.youtube.com/watch?v=TyE-1fKQ ... re=related

those are not holding the base. They are holding the core. Prolly 1mm outside of the base.

[iggyskier]

kind of like the matchstick idea, but a lot bigger tabs with holes for dowels that will be glued to the cassette.

Anything that impedes the expansion of the base during pressing can cause deformations.

Ask iggy about that one.

Good luck with the magnets. Remember magnets slide easily. They have very little shear hold. Getting them out of the cured resin is going to be quite fun also.

What is the appropriate level for expansion inside the cassette? .75MM all the way around? Less?

The swell panik guy and the other frenchy from Richuks journal see virtually no room for expansion in the cassettes.

I cannot believe I have been putting holes in my cores all this time. Obviously outside the layup, duh. I was going to switch to the plastic standoffs next, cause they are much smaller but I just scrapped that idea.


How much deformation Igg?

I don't think it matters how much room you leave for expansion, as long as it is equal all along the metal edge. If it's not equal it will change the shape. Dramatically.

^^^^^

We tried a few cassettes that had specific sections where the base was held it, and we saw different rates of expansion beyond those points - aka magnatraction.

Personally, I think if you are pre-attaching your edges that you are wasting your time building a cassette to held everything in place. There are some fairly large mfg that don't even use anything when in layup (talking completely flat cassettes with NO core tabs even) and they do fine.

I like core tabs because it makes core placement mindless and ensures we get even sidewall thickness side to side.

Never had any problems with bases/edges changing shape when not trying to keep them in place. Score lines and spray adhesive do wonders. Only issues we've had have been when we've tried to do to much and complicate things. I've said this before - keep cassettes as simple as you can.