Curl

I decided to have a go at reproducing the pose in Jian Xu's picture shown at the bottom of my last post. Tricky parts included getting the fingers into the correct position, particularly since it seemed to push the right elbow into odd places, and dealing with the deep mesh overlap where calves met thighs and thighs met trunk.

I'm still struggling to get good quality solid hair and I don't always like the models looking bald! This time I used Sculptris to fashion a short hair style starting from a simple sphere. It's not great but it kind of works.

Here is the cleaned up version in Blender beside the reference picture.

Metamorphosis looked beautiful in the translucent blue but, being made of PLA, I couldn't use the acetone vapor bath to smooth the surface. PLA isn't soluble in acetone. I knew that I wanted to have a smooth surface on Curl, so I thought I would try printing a copy in black ABS.

My first attempt was sliced in Slic3r 0.98 but again I was disappointed with the way it generates support structures, so I abandoned that print and sliced again in Kisslicer. This version looked much more promising and I have learned that the initial raft is an indispensable feature for supporting this type of model.

Here is the model on the print bed and in close up, showing the support structures (under LED lighting).

Here is the bottom section of the support material after it was peeled away from the model. I am still impressed with how well the support separates from the model given that they are both made of the same material.

And here is the final version after processing in acetone vapor.

Computer Graphics Society

My latest search for ideas for a new sculpture led me to the CG Society website where I found some great art.
The first picture I found was by Edward McEvenue and looks like a 3D rendering but, as the artist's own website reveals, it is actually a painting derived from an original image here.

The second picture by Jian Xu was modelled in 3DSMax and once again I liked the unusual position of the limbs and the head presenting some beautiful curves which should prove quite challenging to reproduce.

Metamorphosis

This weekend I created a new sculpture based on the photo of Edward Watson performing in Kafka's The Metamorphosis. I tried to reproduce the pose as accurately as possible and was very pleased with the result.

 I had hoped to print the sculpture without turning on the automatic support feature in the slicing software, but as soon as I had finished posing the model it was clear that this would not be possible. As well as the shallow slopes on the thigh and arm, there were points, on the tip of the chin and the underside of the breasts, that had nothing beneath them. 

I used Kisslicer to turn the STL model into printer instructions and enabled medium support. This time I decided to try printing at 150 micron resolution to reduce the visibility of the layers. I also wanted to find out how well the support material could be removed from a PLA print so I used a translucent blue filament for the 12 hour print.

The support material was more difficult to remove from PLA than with the grey ABS, but after a bit of work it came away surprisingly cleanly.

Here is a quick video of the model on a turntable to show it from all angles.

http://youtu.be/MRIWulQLC5U

And here are a few photos.

Inspiration

As impressed as I was with the success of removing support material from my 'Sascha' prints (both ABS and PLA plastics worked surprisingly well), I am still drawn to the challenge of finding poses for sculptures that will print well without the need for any support at all.
I searched a few glamour and comic art sites and came up with these two examples of the kind of thing that might work quite well.

However, they are both rather similar to previous models and both have the problem of the horizontal right arm which is going to be difficult to print without support.
Then I saw this picture in the arts section of the local free paper and was struck both by the beauty of the pose and the potential opportunity for printing.

I think it looks like a great challenge so I think I'm going to try this one next.

Finishing

The surface appearance of a Fused Filament Fabrication 3D print is determined by a number of factors.

• Size of the print - larger prints will show more detail with a high resolution STL file
• Height of each printed layer - at 0.1 mm and below the layers become much less visible
• Extrusion temperature - some plastics become duller when printed hotter

After the print is completed there are some 'post-processing' techniques that can be used alter the finish.

Cosmo Wenman is making great progress with his artificially aged bronze statues and is planning to release a range of finish materials.

PLA can be smoothed with a hot air gun although there is a danger of warping the model if the temperature is allowed to get too high.

Dipping the model in an acetone bath can work well for ABS.

The newest technique was recently described by Spacexula in this YouTube video and involves placing the model in a heated chamber with a small quantity of acetone which then vaporises and coats the surfaces. The effect looked dramatic so I decided to give it a try.

Here are the results of my first two attempts.

The surface is now smooth and shiny even though it is completely dry and hard to the touch.

Sascha

I love this striking photo by Sascha Hüttenhain and I wanted to use this as the inspiration for a new sculpture.

I had to use a bit of artistic licence to create a pose that would capture elements of the photo but remain printable on my 3D printer.

Here is the digital version of the pose that I wanted to try and print.

Capturing the Sascha Hüttenhain pose

Viewed from the other side

For the 'Pensive' sculpture, I had created a long hair style that would sit comfortably on the woman's collar bones, avoiding another potential printability issue. However, this model is holding her head sideways, so I knew that a long hair style wouldn't work.

Hair is a real problem when using the models in 3D posing software. It usually consists of multiple flat layers combined to give the illusion of depth. This may work for 2D images, but 3D printing demands real depth with solid models and the standard hair add-ons don't work.

One of the most useful techniques I have tried, is to export a hair style as an .OBJ file, import it into Blender and then use the Shrinkwrap modifier on it. It isn't a completely automatic process yet, because it still needs a fair degree of tweaking, but it is much better than attempting to print the original hair model. The finished hair object can be combined with the rest of the body with a Boolean Union join to create a single watertight mesh which the slicing software can cope with.

This model presents several new challenges. The head is tilted sideways; the legs are at a shallower angle; the left elbow is beside the knee, not resting on it; the hands are being held horizontally, one above the other.

All of these factors led me to the conclusion that I would have to turn on automatic support in my slicing software. I would also have to print with ABS plastic because of the way that the support elements will have to break away from the model, leaving the minimum of scarring. I fully expect to have to do some post-processing work after printing this model.

I generally use Slic3r for turning my 3D models into printer instructions, but I don't find it that good at generating support material. Recently, I have had more success with using Kisslicer when I need good support material. Printing models with a small footprint, and this includes support material, is sometimes more reliable if it is laid down on a printed raft, rather than directly onto the printer bed. 

In Kisslicer, I turned on the Raft option and set the Support material density to medium.
I set the model height to 8 cm and the layer height to 0.2 mm, giving a total of 400 discrete layers.

Here is a close-up preview of the printer file rendered by the excellent printer controller software, Repetier-Host, showing the raft (under the feet), the support structures (under the legs) and the individual layers of the model.

Repetier-Host preview render

And here is the 3D printed version.

Printed in grey ABS at 240°C, 0.2 mm layer height, waiting for support material to be removed.

And now, following removal of the support material and surface blemishes.

Removing the support material

Video

Pensive

The 'Sun worship' model took me at least five attempts to get a decent print from, but having finally got it to the point where I was happy with the output quality I decided it was time to move on and try a different design.

There are many factors to consider when designing a model for printing on a 'fused filament' type of 3D printer, like a RepRap or Makerbot. One of the most important ones is the the need for 'support material'.

The printer starts printing the bottom layer onto a flat bed (usually heated to 100°C to make the plastic stick to it) and then proceeds to print each successive layer on top of the one underneath. This works fine for blocks with straight sides and can even cope with sloping sides of up to 45 degrees where each layer projects out a bit further than the one below.

But in real life, things stick out at all sorts of angles and this presents a problem. Just take a look at the middle of your face and imagine how difficult it is to print chins and noses. The printer is squirting hot, runny plastic filament downwards from the nozzle and needs something to extrude the plastic onto. If there is nothing there, the string of plastic will just hang down in mid air instead of following the path that the nozzle is tracing as it draws.

Sun Worship

One way to address this problem is to create support structures which are not part of the sculpture, but are solely intended to provided a surface for the upper layers to land on. 
Another way is ensure that the model has no projecting angles shallower than about 45 degrees.
Look again at the Sun worship model and you will see that all of the limbs, the torso and the head have been carefully posed to ensure that there are no unsupported regions.



I decided that my next project would be a nude sculpture of a woman standing in a pensive pose, one knee slightly bent and arms held close to the chest. 


After working through a number of iterations I arrived at this pose.


Again I spent a considerable amount of time fixing the mouth and eyes and creating a customised hair object.

It turned out that there were several problems with this model. Firstly, the points of the elbows and the chin had nothing beneath them so I decided to add some small support blocks for removal after printing.


In this picture, you can just make out the small disc between the thumbs, as well as the triangular elbow supports.


This should have worked in theory, but in practice the chin support was too thin and failed to print correctly, while the elbow supports ended up too close to the model and caused an unsightly mess.






The other big problem was that my printer can only go up to a height of 13 cm and even using the full print height the model still ended up quite small.
This would have been OK had it not resulted in the fingers becoming too thin to print correctly.
Here is one of the early attempts demonstrating some of these problems.

I made a number of significant changes to try and improve the quality of the print.

• Moved the elbows closer to the abdomen and removed the support blocks
• Repositioned the thumbs under the chin
• Slightly fattened the fingers and thumbs
• Increased the height of the model to 20 cm
• Printed in two halves, with a connecting pin to join them back together

The fingers are little bulky and the seam is still visible but this is straight off the printer, with no post-processing work.

Pensive

Incidentally, you can see the legs of this model being printed in the very first picture of this blog.