Building a Pneumatic Press Frame
and operating a ski press can be extremely dangerous. You can injure
yourself and others and in some cases you can even die. We recommend that
you wear protective eye wear at all times. If possible we also
suggest building a structure (e.g. an enclosure for the press) to protect
yourself if the press malfunctions or self-destructs. Exercise caution at
Overview A ski press is one of the most important pieces of
equipment for ski building. The main function of a press is
to simply provide high, uniform pressure to squeeze ski materials together to
form a ski. In the case of pneumatic press, all of the ski materials,
molds, and bladder are placed inside a strong and rigid structure, or frame.
An example of one our frames is shown below. (Note the reinforced design.)
10 Easy Steps to Build a Pneumatic Press Frame The following steps outline how to build
a relatively simple pneumatic press frame with items that are readily available at your local DIY
store such as Home Depot. A diagram of the frame is shown below.
Note that this frame design is only meant to withstand operating
pressures of 40-50psi. If higher pressures are desired you can
easily substitute with stronger materials such as thicker tubing or even I-beams.
Also the dimensions provided in this howto are guidelines. Your press frame should be designed specifically
for the bladder you choose, the mold dimensions, the desired operating
pressures, etc. It is recommended that you consult a certified engineer
when designing and building ANY ski press or ski building equipment.
Step 1: Gather the Following Materials
2" x 2" x 78" - 0.075" thick square steel tubing (8 pieces)
2" x 2" x 12.5" - 0.075" thick square steel tubing (14 pieces)
2" x 2" x 10.5" - 0.075" thick square steel tubing (14 pieces)
1.5" x 1.5" x 12.5" angle iron (14 pieces)
5/16" diameter x 12.5" threaded rod (14 pieces)
5/16" diameter x 9" threaded rod (14 pieces)
5/16" nuts and washers
Step 2: Prepare the Beam Tubes (BT) The eight
beam tubes are constructed using the 78" long square steel tubing. Prepare the
tubes by drilling seven equally spaced 5/16" diameter holes as shown.
Make sure to drill completely through both walls of the square tubing so that a threaded rod
(5/16" diameter) can fit smoothly.
Afterwards, arrange the tubes side by side and check the
alignment of the drilled holes by using the threaded rods (5/16" diameter).
Correct any misalignment of holes before continuing. Please remember that drilling through steel can be a very dangerous operation,
so seek expert advice/training and wear safety goggles at all times. It is
recommended that a drill press be used to drill the holes.
Step 3: Prepare the Support Legs (SL) The support legs
provide the vertical structure for the frame, separating the bottom and top beam tubes. The support legs
are constructed out of 10.5" long square tubing. Prepare the legs by
drilling 5/16" diameter holes 1" away from the ends as shown.
Note that holes need only to be drilled through one wall of the square tubing.
Make 14 identical pieces of support legs.
Step 4: Prepare the Cross Members (CM)
The cross members provide additional reinforcement for the top and bottom beams.
Without them the beams could bend significantly while the bladder is inflated
which could possibly lead to failure of the press. The more cross members
you have the better, but a minimum of five should be used. In our design,
we use seven. The cross members are prepared in the same manner as the
support legs described above, with the exception of length: the cross members
should be 12.25" long. Again, 5/16" diameter holes are drilled 1" away from the tube's
ends. Make 14 identical pieces.
Step 5: Prepare the Angle Iron Angle iron is used to provide
extra reinforcement for the cross members. They simply
slide into each cross member tube and then bolted inside.
Prepare the 12.25" long angle iron by drilling 5/16" diameter holes 1" away from the ends as
Note that some of the angle iron pieces in the above picture have holes drilled
through both walls. Please ignore this and drill holes only through one
side of the angle iron.
Step 6: Castors If you
would like a mobile press then castors are needed. Attach the castors to
cross members. Depending on the castors
you select you may need to modify your cross members appropriately. In our case,
the castors have a larger base (3"x3") than the square tubing and we had to double up
on our cross members to provide sufficient mounting surface. We simply
made 2 more cross members and bolted them side-by-side as shown.
Step 7: Attach the End Support Legs With your top and
bottom beam tubes (BT) aligned, elevate them (using wood, milk crates, etc.) and
secure four support legs to the two ends of the beams using the 12.5" long
threaded rod and bolts as shown.
It helps to have the beam tubes (BT) flipped on their side for this step as
depicted above. Use a T-square to make sure that the support legs and
beam tubes are perpendicular to each other before tightening the bolts.
Step 8: Attach Remaining Support Legs After
the end support legs are securely bolted, rotate the assembly 90 degrees and
attach the remaining 10 support legs. Check to make sure the frame is
square. Tighten all bolts when the frame is square. The frame should
look like the following:
Step 9: Attach Cross Members The final step involves
attaching the cross members and angle iron. With the frame elevated,
assemble the cross members and angle iron to the frame using the 9.5" long threaded rod,
washers, and bolts as shown below. Note that each threaded rods is concealed
within a support leg
tube, and the angle iron is inside of the cross member.
Here's what the frame should look like when the cross members are secured:
Step 10: Testing Take time to admire your work. Now it's
time to test the frame -- this is a most dangerous part, so please exercise
caution. The test requires a
bladder and molds, so build
them before testing.
Begin the testing by inserting your bladder and molds into the
press. With your safety glasses on, slowly inflate the bladder to 5 psi and
observe the press for any noticeable signs of significant beam deflection
(0.25"+), cracks, loose bolts and nuts, etc. If everything looks
okay then slowly increase the bladder pressure by 10 psi and observe again.
Continue this process until you have reached the maximum operating pressure of
50 psi. Once you've successfully reached 50 psi with no obvious issues,
leave the system inflated for at least 12 hours to further test it for potential
time-dependent failures. During operation, periodically inspect the press
for potential damages, signs of fatigue, or other safety issues.
Finally, we recommend that some sort of strong enclosure be made to house the
press during operation in the event of a failure. Remember that the force
exerted by an inflated bladder can be extremely large and can potentially hurt
you and others around. Exercise caution at all times by wearing protective
eye wearing, a mask, and even a helmet.