Ski Builders Forum

I'm wondering if most people are using silicon inside the bladder where the angle iron clamps down? Or are people finding that just the angle iron clamps are sufficient to create a seal?

I just now inflated my bladder and am humbled by the pressure it can withstand. I only have my bladder inflated to 15 psi and it seems extremely tight. I can hardly image how hard the bladder gets at 90 psi. I just have this vision that the whole thing is going to go off like a bomb.

Do the bladders explode or slowly tear apart if the burst pressure is exceeded?

Esscher

Explode at a weak point. not good.

Is your tube rated for higher pressures?

No glue is used in my bladder.

I use a pair of 2 inch steel angle pieces with 1/4-28 grade 8 bolts and nuts every 2 inches to clamp the fire hose closed at each end. No worries at 60 psi although I settled on 35 psi as the optimum pressure for making skis. I feel that above 35 psi too much epoxy gets squeezed out of the lay-up and the edge tabs show through the base. This air pressure equates to about 6 tons total force on the ski.

Also, at higher pressures my press beams get too deflected which flattens out the camber in the lower form. My beams are on the light side being only W6x20 size. I should have built my frame using heavier beams. I may replace the lower beam with a W8x35.
http://www.engineersedge.com/standard_m ... erties.htm

Also, I installed my air fitting per this design:
http://www.skibuilders.com/phpBB2/viewt ... t=mcmaster
Follow the link to see the actual parts list. This method works perfectly, zero leaks as tested with soapy water.

-S

So glue isn't necessary? it would certainly make things easier and cleaner to do without.

How are people putting holes in their fire hoses for the air fittings? Drill? Burning?

I think the air fitting is a weak point, so I'd like to find the best way to introduce the hole.

To cut a clean hole in the fire hose simply insert a piece of wood inside first and then use a round hole arch punch and hammer. The wood supports the material being cut and prevents cutting through the other side of the hose.

(McMaster-Carr catalog page 2262)
http://www.mcmaster.com/

-S

SHIF:
my hose is rated to have a working pressure of 100 psi. i bought it new from heartland hose.

i have small leakage though the bolts and through the bladder...



I torqued the bladder fitting down pretty damn tight.. i could probably turn it an 1/8th of a turn more.

all in all, it leaks 2psi in an hour.

APS:
I just drilled the hose. i'm not sure this is the best method because the result is not a clean hole. it still is a tight fit if you use a 3/8 drill bit for a 3/8 bolt....you have to spin the bolt into the bladder hole because it is such a tight fit.

I only put silicon in the ends because of the fear I had after reading posts. I know now I do / did not need it. As far as the hose fittings, look at this post. There is a pic of what I use for the inflation of the hose. Workls great, very simple and cheap. readily available at most auto stores. I think mine costs just over a buck. I just used the old drill to make the holes.
http://www.skibuilders.com/phpBB2/viewtopic.php?t=1296
rockaukum

yea, those simple tire valves look good and are nice and simple. I think if I were to do a bladder again, i'd do that. i spend like $40 on the hardware for my bladder valve (the happy monkey style). and for $40 i would think it would be leak-less, and as you can see, my setup is not.