The Once and Future Prints

I want you to think for a bit about your perception of 3D printing. How is a 3D object created? What kinds of technologies are involved? What processes are applied to the part before, during, or after the print? A manufacturing company employee may be thinking about selective laser sintering (SLS) printers that use lasers to target and cure powder to form a 3D object. DIY makers may be thinking more along the lines of fused deposition modeling (FDM) printers, where layers of melted plastic are deposited onto a build plate. Some printers can print in multiple materials or colors, while others only have one option. However, all 3D printers have a few features in common; they all manufacture parts bit by bit, layer by layer, and all of the manufacturing is hands-off. The only time we physically interact with what is being printed is during finishing and post-processing. After the print is done, the part is cleaned up, holes may be bored out, and it may be mounted to an assembly of non-printed components, if the entire print job isn’t an assembly already. 3D printing has exploded in the DIY community as desktop 3D printers have become affordable. Yet it is still a relatively hands-off manufacturing process. But what if that could change?

3D printers are a great resource because they allow us to make things that weren’t possible to make before. It has revolutionized manufacturing and brought making things to a whole new level. To expand the capabilities of printers, most 3D printing companies look to creating different materials and more extruder heads as the next step, because it will allow printers to create assemblies that contain parts made out of different materials. But we don’t need to have a printer that can print an assembly with multiple parts and materials to print a multi-material object. Most of what we need is already right in front of us; a printer, and a bunch of different objects and pre-fabricated parts to play with.

While we consider post-processing a 3D printed part to entail adjusting a part after it has been completed, applying methods like sanding, polishing, sealing, or painting, I would like to introduce a term I am currently calling “co-proccesing”, with its work-in-progress definition:

 Co-processing: Modifying and adjusting a 3D printed job as it is being manufactured to produce content that could not have been created easily otherwise.

 How could co-processing be useful? Below I share a very simple example, an impossible bolt. All files for this are available here. I have a double-headed bolt that I want to print, and I want to put a metal nut on it. I’ve printed this on the MakerBot Replicator 2.

 The Impossible Bolt

An impossible bolt made via co-processing
An impossible bolt made via co-processing

Begin the print job. Once the threads extend higher than the nut, pause the print job. On a MakerBot, selecting “change filament” while paused will move the extruder head to the side and the build plate down, giving you enough clearance to put your nut on. If you are using a different printer, you may want to print two bolts at the same time, so that you can pause the print over one bolt, and do your co-processing on the with enough clearance.

Screw the nut onto the thread. It may be a bit sticky at first. Make sure that you don’t accidentally knock over the printed piece when you are putting on the nut.

Screw the nut onto the bolt with the print paused mid-print
Screw the nut onto the bolt with the print paused mid-print

Continue the print job. The print should finish with no issues.

Alright, this is interesting, but how is it useful? We just made a multi-part, multi-material assembly, only one of the parts was 3D printed, and the entire assembly came off the build plate fully functional.

The finished print of the impossible bolt, fresh off the print bed.
The finished print of the impossible bolt, fresh off the print bed.

Co-processing has potential because it incorporates multiple types of manufactured parts into one print job. You can combine a product’s manufacturing process with its assembly process by placing parts into a 3D print job as it is printing. As a DIY maker, this is exciting. You can design a robot, assemble it while it is printing, and have it walk itself off the build plate upon completion. From a manufacturing perspective, this cuts down on assembly time, as now some of the manufacturing time and assembly time have now been combined and span the time of one print job. Co-processing has a lot of potential in a wide range of areas. If you have seen methods like this or have some examples, or just have a few interesting ideas, I would love to see them!

Alex Crease

A youtube video of this blog:


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