Creating a Frame for Jupiter

I am excited to share with you our 3D model of Jupiter that we will be using in our space-themed VBS decor.  So far, we have created a 3D model of a hemisphere of Uranus here and here.  Now we are focusing on a quater section of Jupiter.  It will be hung from a ceiling against a wall in our main stairwell.  We will use paper mache, again.  In order to do that we need a form on which to place the glue and paper.  The challange is making a form that is large enough for our scale and rounded like the planet should be.  

This is our first attempt.  Overall, it worked pretty well, but we might tweek some things when we go to do Saturn.  I will create another post for Saturn when we get it done, and you can decide which method works best for you.  

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Materials Needed for the Project

Building the Frame

I started with the main structure of the form.  The frame will define the size and shape of the form.  Using the PVC cutters, I cut each of the lengths required (see the download below for the specific measurements).   You can use the measurements that I used, or you can generate your own using the formulas that I provided in the PDF.  However, I would suggest not going small that the radius I used.  The PVC gets really hard to bend at shorter lengths.  

Starting with one side of the frame, I fit together the shorter pieces that will define the radius of the sphere.  I secured those pieces into place with the PVC Primer and Cement

PVC Frame Plan

Download a copy fo the plans for the the PVC frame used in this model.  Join the email list to stay up to date on new projects.  

Using PVC Primer and Cement

Using PVC Primer and Cement is pretty straight forward.  However, it can get a little messy, so I would suggest putting down some paper and wearing gloves.  The purple primer is espcially prone to drip and stain things. 

The purpose of the primer is to clean the PVC so that impurities do not interfere with the glueing process.  When you unscrew the lid, you will find a dobber attached to the lid.  Swirl that dobber on the inside of the fitting a couple of time.  Be sure to get deep into the fitting. Then swirl the dobber on the outside of the pipe a couple of times.  It will dry fairly quickly.  

Next repeat the same process with the cement.  

Immediately push the pipe end into the fitting, being sure to push it all the way into fitting.  Most fittings will have a slight edge that stops the pipe from pushing in further.  Make sure the pipe reaches that edge.  You might need an extra hand to help.   The cement is a contact cement meaning it will start to bond as soon as it touches another surface that has the cement on it.  You have a few moments to make adjustments, but the cement does start to bond fairly quickly.  

Bending the Arc

This is definitely the trickiest part, and you will probably need a parnter (or two) to help.  It will be an interative process of heating and bending, heating and bending.  Patience is key here.  If you move to quickly, you might break a fitting.  To start, use the primer and cement to secure one end of the piece used to create the arc into the fitting.  Brace that fitting against something (like the floor, your foot or wall, etc.).  Use the heat gun to heat the length of the pipe as evenly as you can.  Be careful!  The heat gun is very hot!  Do not put your hand or anything flamable in front of the gun.  

As one person is heating the pipe, another person is slowly and evenly bending the pipe towards the intented fitting.  Go slowly so that you don’t over stress the fitting or the pipe.  Be aware, the fittings that I used are furniture grade fittings.  While they are considerably cheaper than their Schedule 40 counterparts, they are also a bit weaker and more prone to cracking.  So be sure that you are supporting the fitting and bending the acr in such a way that it’s coming out of the fitting as straight as possible.  

Once the pipe is bent into a good arc to fit into the second fitting, use the primer and cement to secure it in place.  Work quickly to maintain the bend.  It would be a good idea to keep pressure on the arc while the cement bonds and that joint gets solidified.  

Repeat the process for the second half. 

Sorry I don’t have any pictures of this process, I was too concerned with getting the fit.  

Reinforcing the Joints

As I mentioned above, the fittings I used in this project are furniture grade fittings.  Also there is is a lot of tension created with the arc.  So I reinforced the the joints in two ways.  I added support wire for each arc to take some of the tension off the joints.  The diagram below shows where I put the wires (the red lines).  To attach the wires, I wrapped the wire around one joint on all sides using figure 8 patterns.  Then, I pulled the wire tight to the opposite joint and gently pushed the joint in towards the center of the curve.  The goal is to provide some slack so that you can wrap the wire around the second joint easily.  When the pressure is released.  The curve will go back to its original arc and the wire with be tight and providing support to the joints.  I repeated the  process for all of the arcs.  

I finished by wrapping each joint in some duct tape.  This was probably unnecessary, but I wanted extra support on the fittings to prevent cracking.  

Wrapping the Frame

Now that the frame is complete, it is time to fill it so that it has a rounded, spherical shape.  To start we wrapped the vertical and horizontal faces with plastic wrap.  This is to keep the filling in place while the paper mache dries.  We found it helpful to tape the middle sections to the frame as we work from the 90 degree corner out.  

Filling the Frame

We used a variety of balloon sizes to fill the frame and create the spherical form for the paper mache.  We started with the 36″ balloons to take up the bulk of the empty space.  This task was much easier using the electric ballon inflator pump.  Those large balloons filled very quickly, and I would highly recommend buying one if you don’t have one already! We also taped small balloons along the frame to give a rounded shape to the form at the edges.  As we put balloons into the frame, we evaluated what size would best round out the shape in that location.  Sometime large balloons were needed, sometime small balloons were needed.  I had a spare piece of PVC pipe with the radius marked on it to be able to measure the sphere as we worked.  That way we didn’t get too big or stay too small.  We used duct tape to secure the balloons to each other to keep them from moving as we worked.  

Once we had a basic shape that we liked, we started to wrap the front of the form with plastic wrap starting from the bottom (what will be the equator of the planet).  The first section of plastic wrap wrapped around the PVC pipe so that half of it was on the flat face and half of it was on the rounded face.  Each layer of plastic wrap overlapped the previous layer by halfway.  The trick is to keep the plastic wrap taut as you move around the form.  With each layer, we filled gaps with balloons or bunched up kraft paper, whatever was needed to create as smooth of a curve as possible.  

Once we got about 2/3 of the way up the frame, it was really difficult to keep the plastic wrap tight.  So, we moved from wrapping it horizontally to wrapping it vertically.  We continued to fill gaps as we worked. When the frame was filled and the plastic wrap covering was tight and secure, we were ready to move onto the base layer of paper mache.  

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