Monday, February 22, 2016

SUCCESS! My Captain America Ball Chair Test Part Worked!

For those of you who have just stumbled across my blog, today is a very good post to land on.  Over the past months I have been working on a large project that I call the Captain America Ball Chair Project. One big step in the process of building this chair I am happy to say has come to a conclusion this morning when I successfully created my first fiber glass molded test part.  All of my previous fiberglass projects have been ones that were of a fiberglass/composite structure and I have managed to create some great things with this type of process.  But with the Captain America ball chair project there are six pieces that need to be made that are fairly large and all of them have to be exactly the same shape and size for the project to work at all.  So with this post I want to show you all the steps together that I took to make my first test part from a fiberglass mold to get this process down correctly.

I started with this simple little form that you see in the photo above.  It is made from Styrofoam half spheres and Styrofoam pieces that make up the box around it that are all an inch thick.  I hot glued these parts together and then took a mixture of fiberglass resin and micro-balloons to make a putty to fillet all the inside edges of the box and around the base of both half spheres. 

I then fiberglassed the inside and outside  of the mold with several layers of three ounce fiberglass cloth.  I let this cure over night and then coved the cloth with a thin layer of putty mixture again just on the inside of the mold and let it cure for a couple of days so that it would be ready for sanding in the next step.
After the interior of the mold had been sanded smooth with 120 grit sand paper I then moved on to spray painting the interior with primer.  I let this dry and then started wet sanding with 600 grit wet/dry sand paper.  I repeated this process of primer/wet sanding four or five times until I ended up with the interior of the mold looking like the way I wanted.... nice a smooth.  Like a baby's bottom.  I next coated the interior of the mold with ten coats of mold release wax.  This stuff goes on just like past wax for your car but is made just for making molds.  By the way it smells nothing like car past wax.  Not bad but just different.  After each coat of wax was applied I left it to dry and then buffed it off just like you would with your car.  After ten coats of wax it looked like the photo above.  I was happy that it look this great at that point.

After all the waxing had been completed I laid down two coats of PVA (Polyvinyl Alcohol) solution  mold release.  This forms a thin barrier over top the mold to make the part release easier from the mold once it has cured.  Two coats of this solution was put on using a brush and after each coat had dried about 20 minutes or so the mold ended up looking like the photo above.  Very smooth and shiny.  I was pretty certain that my test part would work at this point in the process.

I next laid the fiberglass into my test mold.  I made sure that I had enough glass layers in the mold so that when I took it out of the mold it would be plenty strong.  The first layer was only three ounces in weight and then I put down two more layers that were eight ounces in weight.  I then left it to cure over night.

Here you can see that I managed to get the part out of the mold.  The fact that the mold was so smooth did the trick.  I took a small pocket knife and slipped it between the mold and the newly formed part to see if I could start to release the part from the mold.  The blade of the knife slide in as easily as if I was going to slid it under a piece of paper laying on a table.  I could immediately see the separation of the part from the mold.  Kind of like having a air bubble show up underneath the translucent part. I then widened the gap around the mold to allow several tongue depressors to be placed between the mold and the part.  Within a minute I had released the sides of the part from the mold.  I was able at that point to tug on the part and slowly have it release from the bottom of the mold all the way around.  The half spheres were another story.  I needed a little more persuasion to get them to release.  I used a rubber mallet and tapped on the spheres and within a couple of minutes I could see that the spheres were releasing as well. The part was nearing the point where I could pull it free from the mold.  With a few more tugs on the part it came out nice and clean.  Total time took me around seven or eight minutes.  Not bad considering so I am happy it was not a big struggle to get the part out of the mold.

 So here is what the part looks like from what I now call the underside. I trimmed and cleaned the part to remove the PVA mold release and now I have a finished part. 
This is how it looks from the top!  The part is nice and strong and the process that I just showed you worked perfectly.  So it is a great step to give me more confidence in making the six parts for the Captain America Ball Chair project. With the test part completed it looks kind of like a dog dish.  For a very small dog dish but something a bit more complex than just a fiberglass box.  As you can see the part is very smooth and glossy so I consider this test part to be an unqualified success!  Let the party begin!

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