Test Ski Press

After having power restored on Saturday due to a storm taking down the power line at our house a couple days ago, we decided to press one simple ski layup on Sunday to get some notes /data regarding what works well, what needs improvement, etc. in our process. the layup is 22 oz fiberglass top and bottom with a nylon topsheet and wood core with poured sidewalls. we used one of our old, kind of messed up cores that was laying around (didn’t want to mess up the good ones on our first press attempt ever). We skipped the graphics so we can look for internal defects through the clear nylon topsheet.

we used double sided tape and mold release wax around the tape to hold the base to the aluminum sheet

Here’s an action shot while the ski was pressing. we noticed right away the need to ventilate the room when the vac pump runs – smoke from the oil vent was coming out pretty fast and actually activated the smoke alarm at the top of the stairs.. the idea will be to get a small 50-100 cfm exhaust fan and duct it out the basement window. if we can get the air inlet close to the oil vent, problem solved I think.

This was a big mistake – the epoxy flowed into the bottom of the mold and pooled up in there. the silicone sheet was in contact with that pool of epoxy. my suspicion is that the heat from the curing pool of epoxy damaged the silicone sheet. fortunately it isn’t torn or anything, but it looks permanently deformed. I’m hoping it’ll spring back to some extent, but I’m also ordering a spare sheet of silicone in case I need to swap it out. Also – i didnt notice at the time but we shouldve cut the fiberglass to length instead of letting it overhang the front like that – now the fiberglass is epoxied to the mold! whoops!

here it is right before we ripped it out of the mold – in total for this run we did 4 hours of heat – 1 hour ramp from 80 degrees to 180 degrees (deg. F), 2 hours at 180 F, then 1/2 hr ramp down to 140 F before pulling it out.

cutting out the shape on the bandsaw – we did the tip and tail shape with a jigsaw and belt sander

Rough shape cut out

we are going to have to play the game of exaggerating the mold camber to get the correct ski camber. in this run we had 9mm of mold camber, and the ski has 3-1/2″ of camber when it’s resting under its own weight. the unweighted camber is closer to 5mm.

topsheet is pretty flat, we have one minor crease near the tip though.

as far as internal defects, the ski looks clean – fiberglass has no dry spots and lamination seems secure. no complaints there. One issue (we knew we had it going in but proceeded to layup anyway as a learning experience) – the base warped when we glued the edges on. going to need to experiment with ways to keep the base secure while doing the edges to avoid that. A couple posts back there’s more details on how we did the edges and my guess at why it warped is because we didn’t have the base secure to something stiff when we spun it around to put on the 2nd edge. we’re thinking of double sided taping the base material to the aluminum cassette, cutting the base shape on the cnc, then applying the edges without ever removing the base from the aluminum? the tricky part is we don’t have a base mold like a lot of other people use for this process, since it’s all cnc cut.

Here’s the aftermath of the pooled epoxy issue we had before. not sure if there’s a way to patch it or if we should just replace. leaning towards replacing though