Overview  The bladder is the component of the press that exerts uniform pressure on top of the ski materials (see picture below).  The bladder is usually made from a large fire hose or something similar.

In our pneumatic press design, we used a 5" diameter fire hose as shown below.  Without air, the bladder flattens down to about 9".

Large diameter fire hoses can be found at a surplus store or ordered online.  Ebay is also another place to find inexpensive fire hoses.  

 

Steps to Build a Bladder  The following outlines how to build a bladder for a pneumatic press.

Step 1: Gather the Following Materials:

• fire hose

• 1"x1" angle iron (4 pieces)

• 3/8" diameter nuts and bolts

• marine silicon sealant

Step 2:  Cut the Fire Hose to Length:  After you have built the ski press frame and the base and top mold, the next step is to cut the fire hose to an appropriate length.  Cutting the right length is important.   Make sure the fire hose is long enough for your skis and that it can also fit into your press frame.   With most fire hoses, it will require a jig saw to make a clean cut through the material.

Step 3:  Install Air Valves:  Air valves allow your air compressor to connect to the fire hose.  There are numerous types of air valves available.  Make sure that the air valves fit with your air compressor connections before installing them in your fire hose.  For most valves, an appropriately sized hole will need to be drilled into the fire hose and the valve simply installs using supplied washer and nut fittings.  We usually place our valves near one end of the fire hose to allow for easy access during the pressing process.  Apply a generous amount of silicon sealant to the air valve connection to prevent air leaks.

Step 4:  Prepare the Angle Iron:  We used two angle iron bars to clamp each end of the fire hose.  Holes (3/8" diameter) are drilled through the angle iron and the fire hose, and nuts and bolts are used to clamp down the ends of the hose.  Test fit the angle iron clamps to make sure they fit properly on the fire hose.

Step 5:  Apply Sealant Inside Fire Hose:   Apply a generous amount of silicon sealant inside the fire hose approximately where the angle iron clamps will be located.  The sealant will provide an extra measure of security to prevent air leaks in addition to the clamping force of the angle iron.  Rubber stripping can also be used in conjunction with the sealant to provide for an even better seal.  Wait for the sealant to completely dry before continuing on with the bladder construction. 

Step 6:  Securing the Angle Iron Clamps:  Once the sealant is dried bolt the angle iron clamps to the fire hose.  Apply more sealant around the bolts.

Step 7:  Testing:  After all the sealant is dried slowly inflate the bladder to 5psi and test for any leaks.  Leaks are usually audible, however, soapy water can be used to locate air holes as well.  If leaks are found apply more sealant to the area.   Once all leaks are sealed test the bladder to see if it reaches your desired operating pressure (45psi - 125psi).  Remember to take precautions such as protective eye wear when inflating the fire hose.