I found a 1/2" thick 5"x16" I beam at the scrap yard that is 16 feet long. It will cost me around $100US. I have the angle laying around.
I expect 16" wide to be wide enough to build a cassette two skis wide.
I intend to simply weld the risers on the side.
I will put castors under it for mobility.
See any issues?
I do. It is going to be a PITA cutting the I beam in half.
Anything else?
how much vertical space should I allow between the two beams? The square tub one appears to only have 8"-10" while melvs's has 14"-16". I see that the taller one will necessarily have more cassette thickness, but will have more room to work. Pro-cons please.....
From what I see, the only prolbem is that the 5/16 thickness may not hold well under pressure, butI honestly have no idea about that.
Cutting the steel shouldn't be that bad with a sawzall, it's pretty much exactly the same I-beam I have (only 'wider') with the same thickness, and it took time, but wasn't that bad to cut.
looks like it should work. but because i'm paranoid about things blowing up in my face i would bolt the angle risers to the i-beam as well just to make sure things are held together.
i would design as much vertical space as possible - up to a point of course. it gives you more room to work with and the extra space can be easily filled up with your top mold. my press has about 9", which is the minimum in my opinion. actually it's a little too small. we had some serious problems with this issue when pressing Big Kam's Cananas.
I purchased the steel. The recycler who sold it to me cut the beam in half, so I don't have that headache.
I have a question about 2-ski presses though. Do you have an outlet hole, or trough between the two skis for overflow epoxy? Is pooling between the skis an issue that I need to be aware of? I just wanted to take care of any holes I might need before I weld the press frame together.
we have a two ski press and don't have any problems with epoxy between the two skis. There is usually about 2-3" of space in between the skis to take up any extra epoxy.
I have about 14" of usable space in my set-up. If i build some super wide skis they may end up rather close together while in the press. Do you see any inherant flaw in building a narrow, reasonably deep (1") trough down the middle of the cassette for collecting excess epoxy?
I've been shopping for epoxy lately & the question of a heated press has arisen more than once. At first I understood that heat simply shortened the cure time which is not really a factor since I am not mass producing & have no problem leaving a pair of skis in the press for 24-48 hours. But then Roy at QCM suggested that the strength and flexoril qualities of the epoxy increase linearly with increase in press temperatures above 70*F. i.e.- pressing at 80*F will yeild a cure 10% stronger than at 70*F. Pressing at 170*F will then yeild a cure twice as strong as a room temperature cure. That got me thinking....... I have some foam inulating panels & could easily build a hut to house the press. I have an salvaged electric furnace which I could direct into that space & probably reach temps above 150*F.
Does anyone have experience with heating your press environment? Was it worth the headache?
On the last pair we pressed, we used the qcm and left it in the press for almost 24 hrs. When I took them out, they delaminated by themselves, just from the stress in the bases and metal edges. It was really easy to peel the layers apart, but after two weeks it has gotten much stronger. I talked to Roy and he said I probably would have to leave it in the press for 3 days (@ ambient temp) before it was safe to take out. Anyways the conclusion is heat will make it much stronger and cure faster. A big snowboard manufacturer uses QCM and presses at 200f for 22mins.
I've given much thought on the best way of heating the press and one thought was creating a insulated box around the press. While this may work, I think its may not be the best way, since you end up having to heat everything. My other ideas were to use heat cable under the mold or a silicone heat blanket. I ended up ordering a silicone heat blanket and am waiting for it to arrive. It seems to be the best way, since it cost just a little more than the heat cable, can be moved from mold to mold, and puts almost all the heat into the ski.
I'm not sure yet if it'll be worth the headache. If you want something quick and easy, stick with west systems epoxy. We have been using it and haven't had any problems.
Like I said, stay tuned. We haven't made too many skis this summer, but we have been doing some behind the scenes tinkering.
What sort of temperatures can you expect from the heat blanket? How well can the temp be regulated & how much did it cost you? Roy also mentioned that the product he was recomending to me only had a 15-18 min pot life. That seems managable once I am experienced but I worry that my first layup will flash before the press (esp if heated) can squeeze alot of epoxy out. That would leave a overly thick & HEAVY ski, would it not?
I have yet to source or price West Systems Epoxys. I am awaiting a call from Duratech/Revchem regarding their products & obviousy I have researched QCM. Given your experiece to date would West Systems be your best recomendation. LittleKam what about you?
Further discussion along those lines, I have never layed up fiberglass. I have talked about it alot & I laminate granite with polyester resin several times a week so I am not totally clueless, but. Are their any rules of thumb you can share for adequately wetting out your glass with out too mych excess? Do you roll on the epoxy?, brush it?, ever tried spraying it. Any other rules of thumb?
On second though, I'll start a rules of thumb, or helpfull hints thread.
I really like the Duratec epoxy (about $60) because I can get it locally and I know it works. I've spent over 130 days on one pair of skis this last winter that used the Duratec and never had any problems with delaminations.
But recently I switched over to QCM simply because of the price. But I wished the retailer would've mentioned something about the heating issues when I was ordering. Because if it turns out that I need some sort of heating blanket I'm screwed with about a gallon of epoxy I cannot use. The last pair of skis I made with Big Kam, the Cananas, were pressed using the QCM stuff and they didn't seem to have any delam issues. But I'm not too sure how they're looking right now after Big Kam skied on them.
For wetting out the epoxy, I just pour a large bead down the center of the fiberglass after it's layed in the mold. Using any sort of flat scrap material I spread the epoxy around until all of the glass looks wet and is transparent. Nothing really special to it. The epoxy isn't too thick so it spreads around really easily.
We are using qcm emv-0049 and the eca-408, which is different from what little kam is using. This combination give a pot life of over 45 mins. If you are laying up a pair at a time, you definetly need more than 15 min pot life. I would estimate around 20-25 minutes per ski. The eca-313 may be fast enough that you can get away without using a heated press.
west systems has been working ok for us now. We haven't had any delam problems associated with the epoxy and it is readily available.
The heat blanket is rated to 450f. I can't give any performance details until I have it built and running, but it should hold 200f to within 2-3 degrees.
You should have all the resin and hardner measured in separate cups ready to be mixed. Don't mix too much at once (<200 grams) or else it will get too hot.
