Aligning bases with cores...........and mold release systems

[petemorgan(pmoskico)]

I am curious what other folks are using for the mold release layer. And how are you aligning your bases with your cores?

I use two sheets of 1/8 inch thick Vinyl - acrylic (plexiglass) to sandwich my layers. it costs about 100$ for a 4 by 8 sheet if I remember right, though it has been a while since I have needed to buy it, because I have been more careful about not letting it crack. The plexiglass has worked pretty well for me for a couple reasons but I am ready to move onto a better system

Plexiglass has been a good friend of mine in ski building because:

1. Epoxy doesn’t stick to it, though, I do get a little bit of epoxy residue left over sometime that is difficult to remove/scrape off. Should I be adding a mold release film of some sort?

2. The 1/8th inch thickness helps buffer any small imperfections in my mold. I also put an 1/8inch sheet of plywood in between the Plexiglass and mold, (both top and bottom)

3. alignment of bases to cores is easy (though crude). I use double sided tape to secure my bases to the mold. I then draw alignment marks for position of cores because it is difficult to see the bases once VDS and fiberglass is on. (i am basically just eyeballing my cores to the correction location) and then to secure my cores during wet layup, I drill into the wood thru the plexglass and into the plywood behind it. And then the cores will not shift during pressing. (drilling outside of net trim) so my plexiglass has a bunch of holes in it, but that's a side note

I see that a lot of people are using aluminum sheets instead of plexiglass. How do you align your cores and keep them from moving during pressing? any chance of getting some moderately tight tolerances because I would really like to start using inserts in my skis.

[twizzstyle]

For mold release, I use aluminum sheets top and bottom for my cassette, I give the bottom one a light pass with mold release wax (just for extra insurance), but the key is parchment paper.

Parchment paper is pretty cheap, epoxy doesn't stick to it at all, and it can take the heat of layup (don't use wax paper, it's not the same as parchment paper).

For core alignment, I do locator pins. I drill two holes, one in front and one behind the inserts, roughly in the center laterally (doesn't matter if they're off). I line up the core exactly where it needs to be on the base, and then superglue two small sections of wood dowel to the base in the holes. Then during the layup, I just have to place the core over those dowels and it is exactly where it needs to be and won't shift.

The only pain with this, is you have to cut two little holes in your fiberglass/etc to go over the dowels. I've forgotten this before, only realizing it after I had started layup and had to panic to cut the fiberglass.

[vinman]

I use the same method Twizz does with some added insurance. I hot glue some small pieces of MDF scrap to my aluminum sheets. I just cut a small square of the parchment out and cover it with hot glue and the MDF to minimize epoxy seeping under. So I have the base pins plus some added insurance of the external locators. These cut off with the flash.

For position the bases on the aluminum I just use some lines drawn on the parchment that give me center marks for each ski to keep them in line with the plane of the mold. I also draw lines to make sure I get the tip where it needs to be so that my tip rise comes out right.

I do aftermarket inserts. Google binding freedom inserts.

[prospectsnow]

hey twizz,
keep your cool.
I cut my glass over the locator pins during layup, while wetting out the first layer of glass with reused old razor blades. The middle is usually still sharp enough to cut the glass pretty easy.