It was the first time the team tried to build a master completely of sculpted and sanded bondo. Bondo is a really good material to work with, but sometimes a little slow to achieve the desired geometry and finish. Everything starts by designing the 3D model. The tricky thing here is to build the model at the right scale, otherwise the helmet wont fit or it will look like a bubble-head. For solving that problem we built a paper version of our helmet. Three different versions were built until getting the right scale.
Once we got the paper version with the right scale, we covered it with a thin coat of bondo. This way the helmet will be strong enough for a one-usage mold of plaster of paris. Making this mold, we will be able to get a full bondo copy of the prototype built in paper. A good point to start sculpting the real thing.
This full bondo cast its just a "sketch" of what is going to be the master. For a better measuring and sculpting facilities we sliced the helmet in 5 parts: the Chasis, the screen, the "brain" and the 2 "ears". Dividing the whole helmet in smaller pieces will make it easier to sculpt. Then, when each individual part is finished will be attached to the chasis to get a full assemblied model. The key thing to get in mind while building this particular master is that the chrome finish that the plastic cast will have requires a smooth and continius geometry. If its not smooth and continious enough the mirror effect of the chrome will reveal "waves" and imperfections on the surface.
With that being said, the curve lines of each part depends on the part to be attached to. As the screen of the helmet its the more espherical element of the master, we decided to start building it first. We made some chop sections of the 3D visor and printed them into paper. Then glued the paper on thinn wood and cut. We built a case in wich each chop fits in its right position as a guide of curvature. Then, we placed inside the sliced visor guides and filled the difference with bondo. What comes next is a lot of hours of applying bondo and sanding again, and again untill getting the desired geometry.
Once we had the screen done, we built few wood guides for fitting the chassis in relation with the screen and the position of the "ears" hole. This was a critic and slow process of simetry on both sides. We used a "modular" system of wood guides to ensure the relation of the curve lines between the surfaces of the chassis. To mantain the relation between the "ears" and the "Jaw" we built a soft wood + 1mm pvc sheet.
The next step was to build a wood guide to create a full bondo "brain" with the right curve lines. With this kind of soft wood mold, you can get a raw surface but a good geometry. Fill with bondo the mold, pull out the piece and mark the surface with a common marker. Then sand to reveal the iregularities, apply bondo on the raw surfaces and sand again. The proccess requires few layers of bondo+ sanding untill getting the good result. Then we used the same guides system to create the female version of this "brain". This way we could transfer the form to the chassis and the "brain" will fit exact and smooth. For doing it, we gived few coats of liquid soap to the female (waiting for the liquid soap to dry), then apply bondo on the chassis and push the soaped form against the fresh bondo in its right possition.
Whit the "brain" done, the last curve line left was the back of the neck or nape. We added another wood guide to the "modular system", and filled the difference with bondo. With this done, we should have the overall geometry of the master.
At this point, and after tons of hours of sanding and applying small coats of bondo, we were ready to start working on the iconic ears of the helmet. Definitively, not an easy job.The steps to follow are, first of all, build a kind of cover of the "ear" holes. This cover, must have the overall curvature of the chassis and fit perfectly into the "holes". (The square in the middle of the cover is just a reference for the rest of the "ear")
Once the covers were fixed and screwed, we built the actual ear, that is going to be attached on to the cover and leaves a continious margin between the ear and the chassis.
When we worked on the "brain" we thought it may be cool to leave a margin between the "brain" and the chasis, just like the ear does. For doing that, we added few layers of soft wood on top of the surface of the brain untill getting de mesure of the desired margin. Then, we sculpted some free space on the inside of the model, and pushed the wood covered brain against the chasis in the right possition. The result: a removable brain with internal screws and a continius margin.
We had to build another wooden guide to the modular system for completing the nape. Placed it in the right position and filled the difference with bondo and absolute attention to the detail.
Continuing with the "ears" work, we masked with tape the cover, leaving a continious margin to apply an homogeneous "floor" to place the ears. Then craft a U form guides to finish the border between the chasis and the ears and then, center and fix the ears on the covers.
After few hours of sanding and recovering curvature lines on the chassis, we filled the gaps between the ears and the covers and proceed to open a reference hole in the ears surface.
Once we opened the hole, we built a wooden guide to craft a bondo female of the correct geometry of the definitive hole. Using a thin film of liquid soap will help demolding the female from the bondo. Despite the result is not perfect, has the right geometry, and giving it a good finish its not going to be a big deal.
Then, we continued the crafting with the front of the "jaw". The original helmet had a flat chin, so we decided to add it to our design instead of the rounded chin we had at that moment. For doing that, we printed in paper the desired geometry as a reference. Once we added the "front flat chin" we continued with the sides. Adding carefully measured and sanded supports, and helped by a flexible 1mm PVC sheet, we filled with bondo the difference until getting the right curvatures.
Continuing with the "ears" build, we asked a close friend to CNC over a plastic sheet the inner drawing of the original ears. With the help of a silicone cast, we transfered the surfave to a bondo piece. Then trimmed each ear to the desired size. What comes next is possitioning, sticking them in place and filling the joint with bondo and the help of the rounded face of a drill.
The last iconic characteristic left to add to the model, is the separation line between the front and the back of the chassis. For doing it properly, we built the flat line in wood, then got a silicone male of it, and used it to form the rounded line in the bondo. The system is quite simple: open a bigger whole than the final line, fill it with bondo and then push against it the silicone male adapting it to the curvature.
The next step before thinking on priming, assemblying and finishing the master, was to replace the "visor" for a cover plate that would be used in every cast as a reference for cutting the housing or socket for the huge visor. This way, every visor and every cast will fit perfectly.
With all the individual parts of this model done, then next thing was to work in all the joints of the assembly. Once done, we continued by rounding all the edges before priming. One good tip for doing it, is to use a marker in every edge and then flat sanding and measuring the resultant white line. Then, round every flat sanded edge patiently and slightly sand all the marker to remove it.
After rounding all the edges to 1 mm, its prime time! For applying prime correctly, and without loosing overall "resolution", we thought would be easier to print first the chassis separately. Then put toguetther the "ears" and the rest of the parts, mask the allready primed chassis and prime the rest of the assembly to the detail. This way we would have an homogeneous applied primer with a thin separation line between coats really easy to sand.
With the primming done, we were exited to know that just few hours of sanding and polishing were left to finish the master of this iconic helmet. We started wet sanding with 400 grade sandpaper and absolute attention to detail, and then, scalated patiently to 600, 720, 800, 1000 and 1200. The next and final step was to polish with extra fine commpound and a cotton cloth 3 or 4 coats untill the desired finish was achieved. Done and ready to continue with the molding!
