3D Printing is a technique that is also sometimes referred to as “Additive Manufacturing”. This, we often enjoy telling people, is a method for “making without waste” because you only add the material you need rather than subtracting it which is often the case with traditional manufacturing methods.

Well that’s not strictly true as you find out on your 3D Printing journey. If it’s one thing that 3D Printing struggles with it’s overhangs, where there’s nothing underneath to print onto. The regular answer to this is to click the “Create Support” button in your slicing software.

You can see an example of this in the picture below which was a 3D Printed soldier that I was asked to print for a school project. It’s actually not that easy to see it’s a soldier from how the final print turned out. The support material has encased a lot of the figure and most of it was created because of the overhang caused by the hat brim.

Soldiers

The material was carefully (and laboriously) removed after printing to leave the acceptable final painted version you see above. The time spent on removing support material from prints, not to mention the mess and waste of the tiny shards of material that seem to go everywhere, has led me to explore better methods.

Whenever 3D printing anything now I look for every possible opportunity to do so without the use of support material, and also at the lowest possible level of infill I can get away with.

One of the techniques I use is illustrated with these Voice chairs that I was commissioned to print recently.

Voice Printing

There are plenty of overhangs in this model and if you try to print it in one piece this is what Cura adds in the way of support :

Chair One Piece

There are approximately 9 grammes of support material required which is over 20% of the total print in this case. This is wasted material that has to be removed from the model, adds to the print and post-processing time, and reduces the surface quality.

So, I split the model up into six separately printed parts as shown below with their associated print times and weights. Only a small part of the model (under the arms of the chair) needed support in this method and that generated less than one gramme of waste.

Chair Construction

The assembly time to glue the parts together was much shorter than the time I would have spent removing support, and I ended up with a high quality model as a result. Also, printing in parts also allows you to use different levels of infill throughout the model. This means that your infill can be selected as the most appropriate for each piece, rather than it being dictated by the requirements of just one small part of the whole model.

The data summary and comparison for this print is as follows :

One-piece Print           Total Print Time :        8hrs 49 minutes

Total Material :           44g (includes 9 gramme of support)

                                    Support Removal :      Too long to contemplate!

 

Multi-piece Print        Total Print Time :        5hrs 37 minutes

                                    Total Material :           36g (includes 1 gramme of support)

                                    Assembly Time :         10 minutes

 (Note  :  for gluing PLA I use Evo-Stik Serious Glue)

So, making the model this way saved me over 3 hours of print time, the support removal time and 8 grammes of material. This saving became even more significant for this commission because I had ten chairs to make.

So the next time you have a print with overhangs that would require a lot of support material, consider splitting it into parts. Some advanced techniques for how to do that will be covered in a future blog, but if you want any further advice on this technique in the meantime please contact me on s.cox@createeducation.co.uk

Steve Cox

Education Ambassador

CREATE Education Project

In The Classroom

This is a professional development resource to allow you to learn more about how to reduce support structures in order to more effectively deliver 3D printing in the classroom. It is also a useful resource to show to students during the design development phase of project work when they are working independently to design their own products.

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