Hey All:
I am, either fortunately or unfortunately, not a mechanical engineer. So when I look at the frame and hear about '40 to 50 PSI' required to press out a ski, I like to think that is the same sort of pressure that is in my mtn. bike tire. What am i missing?
I understand that its all about uniform pressure from tip to tail, but can't that be acheived (on a WAY less engineered-out frame) by a torque wrench and a home-made clamp press. Has that been tried yet? Seems to me that the cost and spirit of that is more in tune with the garage building scene.
Anyways, killer website and you guys are on it!
Endless Winter
Td
frame overkill
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
The frame needs to be very stong! While 40 psi does not sound like a lot, over the length of a ski it is quite a bit of force. (ie 5"x72" area at 40psi is 14,400 lbs of force pushing the frame rails apart, that's only for 1 ski, double that for a pair) While this is distributed along the rail, it is still a lot of force.
A clamp press will work, but it is hard to get even pressure along and across the whole ski.
-kelvin
A clamp press will work, but it is hard to get even pressure along and across the whole ski.
-kelvin
-
tdog
press again
Well, totally understand the PSI and how it adds up - thanks for the clarification. Have you (or anyone else) messed with a modified clamp scenario.. maybe still using drilled flat steel and a consistent pattern of clamping to acheive the same. Thoughts on a trial effort for that?
t dog
t dog
i really think a clamp press will work. it was actually my first option when i started to build skis. but when i began designing the frame i realized that you get much more out of a pneumatic press (uniform pressing and easy adjustability) than from a clamp press with almost the same amount of effort.
the thing with a clamp press is that it's difficult to get uniform pressure throughout the ski as Kelvin mentioned. but i think this can be achieved by using sand or water creatively. another drawback is that you may have to make a new top mold every time you change your bottom mold.
the thing with a clamp press is that it's difficult to get uniform pressure throughout the ski as Kelvin mentioned. but i think this can be achieved by using sand or water creatively. another drawback is that you may have to make a new top mold every time you change your bottom mold.
- Kam S Leang (aka Little Kam)
I have tryed clamping with a double mould. I got a lot of blisters in my hands, and compared to a pneumatic press there is not enough space for required amount of clamps (ca300kg/clamp=50-100 clamps.) and not enough time to tighten them. By the way you have done so it is time to untighten. bottlejacks would be a better option, but you would have to be very accurate when you build the molds. To even out the pressure you can use a cork mat (or even better a silicon/rubber mat if you can find one. ) If you want to experiment and develop your skills there is no good alternative to a pneumatic press.