Ski Builders Forum

Hi everyone!
I don't know if anybody has done this before me but I constructed a press for which no machine is needed to build up the pressure. Instead of filling the fire hose with air and keeping up the pressure with a compressor, I half-filled my hose with water and just pressed the two parts of the mold together with the help of a lot of screws!

This way I created very even pressure at any position of the ski - it worked wonderfully! I will post the pixx ASAP!!

greetings from Austria!
schoeckl

A friend of mine used a screw press and he did not use water.

That is nice to see that somebody is experimenting a bit, rather than just copying a pneumatic press.

Go ahead.

I love this idea !
Do I need to say that an hydrolic press would be way safer than a pneumatic one in case of failure ? (the water doesn't blow as it's not compressible)
Hope to see some pics and a complete report on it soon !
good luck

Ok, here are the links to my pixx! Sorry the description is in German but I guess things are self-describing. If you have questions anyway, let me know!

production:
http://picasaweb.google.com/jakob.leder ... kiEntsteht

ski-test:
http://picasaweb.google.com/jakob.leder ... pperySlope

happy to get a lot of feed-back!

Einfach Genial!

Really like the idea with the half filled fire hoses combined with a screw press. Simpler, safer and probably less expansive as well. A state of the art example of a KISS-solution. Did you use a torque wrench to tighten the mold?

Nice and simple way to make cool base graphics as we

could you please develop a litte about how you did your base grafics ? my german is limited to "Guten Tag!"....
Are you skis 100% wood ? (no tipspacer)

Good work, I love it !

nice work! i like your idea for the press!

Not sure if it is known or not but you can get a special valve that will allow you to inflate (or put in) water. It will work with a scrader type valve (one like on auto tires). Try a tractor supply house or a tire dealer. Just a thought.
ra

I really like the design. KISS

I'm in the phase of designing my first press, and I have been thinking about a similar idea, but I have been thinking of filling the hose with air. Water makes more sense because it’s non compressible, safer regarding stored energy, but it’s messier. I think I would like to put a valve on to make it easier to fill.

Just and idea: If you put a pressure gauge on the hose, you could measure the clamping force. By using a torque wrench and some calculations you could predict the clamping force rather accurate.

Ok, here are some details:

BASE DESIGN:

it's really simple. I used a transparent base and underneath I put a mountain-map of my favourite ski-resort - which is Monte Rosa by the way

HOSE:

FIlling the hose wasn't messy at all. To make sure no water get's lost, two things are important:
-To seal the ends of the hose make sure to do so in a self-locking way, as seen in the pic. Where grey is the metal, blue the hose and red the screws. SORRY, I HAVE NO ACCOUNT FOR THE GALLERY YET
-this adjustment is only tight once water pressure is applied. If you let the hose lie on the floor it will propably leak. To store the hose you can hang it over a sort of bar, having the ends face down. This guarantees enough pressure to make the ends tight. Don't forget to have about the equal amount of water on each side!

@rockaukum: I don't think it's necessary to use a valve to fill the hose as I am trying to leave away any item which is not really necessary!
To fill the hose, I screwed one end and then filled it from the other end with a watering-can, released the air and screwed the second end.

when filling the hose, you will probably have to screw and unscrew one end a couple times until you have the right amount of water in the hose. But once you've managed that, you won't ever need to unscrew it (unless it's leaking.

Make sure, that no air is in the hose!

When screwing together the two metal plates, don't screw them too tight as the metal will bend and the ends will leak!

About calculations for the clamping press:

I did none of all that. No Gauge, no torque wrench, no nothing. I tightened the screws as hard as I thought would be enough. I could tell very well by squeezing the ends of the water-hose, which finally were as hard as a rock ;-)
What I did was to make sure that lower and upper part of the mold were always parallel!

About my skis:
for the core I used a board of ash-tree, cut it in stripes of about 3/4 of an inch, and then laminated it with epoxy

the core is about 6mm thick at tip and tail and 12mm in the middle.
I neither used tip spacers nor side walls. Since this was my only second ski, I tried to keep it as simple as possible![/img]

6mm at tip and tail !!! that might be veeeeery stiff !

About having the same quantity of water in both hoses, do you think it would be managable to have a tube between the two hoses so water can comunicate from one to the other. You would be sure you have the same pressure in both hoses (I guess).

For your base grafics, I love it ! I would just be worry about delamination by putting a layer of paper in my layup, you'll tell us how it last...

continue this way, it's very inspiring !

Schoeckl this is brilliant! I think I'm going to give this a try. With a little plumbing and heating tweaks you can probably have a heated water press for less than the cost of a heat blanket.

dante wrote:With a little plumbing and heating tweaks you can probably have a heated water press for less than the cost of a heat blanket.

I was thinking about the same thing. I think it would be manageable. I have a small water heater I got for free. I think it delivers about 70 deg C (140 deg F) at max. Fitting it to my PID controller may be possible as well, but the delay might bed to long (because of the time it takes to heat the water). Some tubing, fittings and a circulation pump that’s rated for this pressure, and I’m done. My only worry is what to do with my compressor… OK, I’ll have to buy a air driven torque wrench.

What if you had the water heater on in advance an used a valve to fill the bladders after layup? You could then close the valve to apply pressure. Not sure how quickly this could happen so it might be risky.

I think I might try closed system with a mini tankless water heater and a water pump to circulate the water so the heater remains active. My main concern is the press I use -its light-duty for vac molding. I think if i change the cattrack from wood lath to 3/4" aluminum square tubing it should be OK.

Hey heads up. Just thinkin about the idea of heating the water in schoeckl's design - don't let the water heat to anywhere near boiling. What started out safer than a pnuematic press would then become much more dangerous. Steam generated would change expected pressures and, in the event of failure, would truly be catastrophic! Flying debris AND burning hot water. At the very least I would recommend some sort of pressure relief valve in a heated-water setup. Any research into "hydronic" (moving heated fluid) systems might provide useful info. Very imaginative thinking nonetheless!