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Pressing the ski

Category: ProcessCompiled from 2 source threads

Quotes are verbatim and attributed to their original authors.

Pressing is the moment the wet layup is closed into the mould under heat and pressure until the epoxy cures. It is short, irreversible, and where several build-long decisions finally show themselves — in the camber, in the base, and along the edges.

Set the camber in the mould

Camber and rocker are built by the shape of the mould, and builders fine-tune them by shimming. One journal describes shimming a flat mould with offcuts of base material to create separate camber zones fore and aft of the binding:

"I shimmed my mold with scrap pieces of base material to make the two camber sections fore and aft of the binding mount area. The camber sections are about 2.5 mm of camber relative to the center of the ski and the overall camber is 4 mm."
— Dr. Delam · thread #1801, "Soul Skis"

Heat is applied through the mould — one builder ran 180 °F on the bottom and 140 °F on top — and the temperature and cure schedule should match what your epoxy calls for.

Edge gaps: the classic press defect

A common disappointment when the press opens is a short run where the steel edge has eased away from the base — a fraction of a millimetre over a few centimetres. A detailed thread (#5367) worked through the causes. The mechanism is hydraulic: gelling epoxy, squeezed under pressure, forces its way between base and edge and overcomes the tack glue:

"I'd have to agree that the epoxy hydraulic'ed the edge away from the base. Could be bad/not enough glue."
— sammer · thread #5367, "Edge gaps after pressing"

The most experienced reply pointed straight at the superglue holding the edges on:

"The only time I have seen this happen is if I did not put enough glue on the teeth. I generally put a small dab on every 3rd tooth. CA glue can go bad with time, shelf life is generally about a year."
— vinman · thread #5367, "Edge gaps after pressing"

Keep the superglue fresh

Old, frozen, or over-applied cyanoacrylate all fail. Storage matters, and it cuts both ways:

"3M has guidelines on storing superglue. For longer periods they recommend storage in the fridge (not freezer) to extend the shelf life. However, if you start using the glue more frequently they recommend to keep it out of the fridge in order to avoid condensation inside the bottle."
— chrismp · thread #5367, "Edge gaps after pressing"

Practical takeaways from the thread: buy fresh glue if the bottle is a year or more old, put a small dab on every third tooth of the edge rather than flooding it, let it fully set before pulling the base off the template, and don't pressurise so fast that gelling epoxy gets squeezed out before the sandwich is closed. Reassuringly, small gaps usually "grind out to be barely noticeable" during tuning — "if you go to the store and look at skis closely you will see way worse things."

Source threads