Ski Builders Forum

For the last 6 months we have designed and built a steel press frame, molds, templates etc. We FINALLY pressed skis yesterday but ran into HUGE problems. After our epoxy tweaking out and burning 50 pairs of latex gloves off our hands, we finally had two laid up skis in our press.

Heres what were working with:

-un-laminated hemlock cores
-4oz biaxial (0-90) fiberglass
-Durasurf clear topsheet
-Durasurf bases
-CDW steele tempered edges
-QCM EHV-0050 resin and ECA-315 hardener 5:1 ratio

15 hours of continuous pressure @ 50 psi and decreasing temperature (17*C to 10*C or approx. 70*F to 50*F)

We decided to use a thin, soft core with the lightest glass to create a light, soft ski as a control for later skis and materials (to gauge stiffness and weight from).

Our hoses were standing at around 3-4in, which meant that they only contacted some of the ski.

The problems:

-cores shifted down the ski leaving core-less tails
-topsheet and underlying fiberglass delamed
-epoxy is brittle and cracks when skis are flexed
-the hose didnt press evenly in the tips (which is probably the cause of the delam.)
-edges pushed out on one ski underfoot (almost as if the epoxy had no where to escape and pushed the edges out---we didnt cut the tape off the base near the edge to allow epoxy to escape there)

-when we tried to cut the excess material off of the skis 16 hours later, the vibration of the saw caused the glass under the topsheet (with topsheet still attatched) to delaminate around the sidewal of the ski

Any help is greatly appreciated

Dude, that is exactly what happened to me on my first ski. All I can say is keep working at it and learn from your mistakes. Be sure and nail your cores to the mold. I also put tacks around the edges to hold the base in place.

Again, keep working at it, and most importantly, don't expect too much out of the first pair of skis (or the second for that matter). I was stoked when I made it down 1 run without the skis blowing apart (I also won a of couple of bets). But, once you get your third pair out, it is all easy from there on out

I am sure you have thought of these things but here are my thoughts: I would double check your epoxy measuring and perhaps do a test section with your epoxy. Go through each step of the process ask yourself what went wrong and how you can fix it.

Also, most of the presses that I have seen on this site don't use a cat track below the fire hose, I believe that this is an excellent method to allow even pressure distribution over the entire part. It requires the use of a simple cassette, but I believe that has it's advantages as well. With a cassette you simple use a mold release agent and you don't have to worry about all the plastic and tape to keep everything clean. Your ski's will need a few passes through the base grinder when you take them out of the press but that isn't a problem. Granted both a cassette and a cat track cost more money, but I think they are truly worth it, especially if you plan on making a number of ski's.

If you are using inserts the method that Lindsay suggests here works excellent for lining up your cores http://www.grafsnowboards.com/phpBB2/vi ... .php?t=183

My 2 cents.

I had some similiar problems with edges pushing away from the base well pressing. I was super glueing the edges on and using a couple of plastic bumpers to guide the edges. to fix the problem I added more bumbers to my mold every 5 inches down the the running length. these bumpers are about one inch long and the thickness (height) is less then the height of the edge, so that the overhanging sidewall can go over the top of the bumpers without effecting presure. These bumpers will then be the guides for the shape of your ski and not allow the base to shift as well as hold the edges from pushing out. ALSO when I attached my edges to the base I weave light weight fishing line from edge to edge down the length of the ski pulling each edge in towards each other tight to the base. Then super glue and clamp. If you are doing rap around edges with seems at tip and tail you can tie the edges together so they can not pull appart. You can see a small impression in the base from the fishing line but it grinds out.

I am interested in the idea of a cassette for the ski and the track system, can you explain more or give me a place to find info?

Best of luck

Heres the progress so far...The problem with the epoxy, acording to Roy at QCM is the temp. This epoxy was recomended accidentally to us for low temp curing because of the hardeners fast cure. unfortunately it is a HIGH TEMP EPOXY and therefor only fully cures at temps. greater than 150*F. Since we are dealing with 50-70*F in our garage, our skis will take 2 weeks to cure---not good. AND they still wont be fully cured.,

As far as the edges go, I think I will cut slits through our tape over our bases to allow epoxy out, this should take care of edge blow outs. Well see how it goes.

I am also thinking of using super glue to hold on the edges followed by either a coat of epoxy or a coat of jb-weld or scotch weld as reinforcement prior to pressing

-thanks for all the help so far