Is it possible to print toothbrush bristles using a common FDM 3D printer? I am particularly interested in the width of bristles, closeness together of each bristle, and the flexibility of each particular bristle.
Actually last year a group did use a normal FDM printer to 3d print hair, brushed, etc. See the press release from Carnegie Mellon University
That said as far as I know you will not have access to this process, and is probably under a mountain of patents and other innovation killers.
Now how to do this outside of fancy software.
For a FDM printer the smallest nozzle I ever got was 0.1mm, it jammed instantly. One could print rows at this precision.
Now we have to move to something more advanced, such as DLP. Not the materials you want, but closer to the size you want. a formlabs can print at 25 microns. Which as a hair is 17 microns, you are "close enough" .. but a resin would be brittle and break. They do have other materials such as flexibles, but I am not familiar with them enough.
Also just going to mention. Tiny slivers of plastic is more likely to cut you than comb you.
At this point, an FDM printer probably wouldn't produce good results if you intend on printing the same design as current toothbrushes.
Each strand is about 0.007" in diameter which is slightly larger than the typical minimum diameter that can possibly be extruded. This doesn't leave much room to provide a well enough surface between layers.
With features this small you might run into issues with resolution and accuracy of the machine. The resolution may determine how well the strands are printed separately. The accuracy may determine how well each layer print over each other. If your machines accuracy is about 0.0005", then expect your layers to have run-out of about 0.0005"-0.001" on a 0.007" size feature. I'm also not accounting for how well the machine is maintained/tuned, which could detriment both resolution and accuracy.
So, it's possible on an FDM, but not probable at this time.
To help your odds:
- Slow your feed rate way down (maybe 30-40mm/s)
- Watch over and under extrusion. It will be more evident on smaller features like this. It either will look like a big blob or pretty much nothing. You should have settings in your slicer to help compensate.
- Clean your extruder and drive gear and tune the tension on filament in the extruder assembly.
- Use quality filament! If the filament is out of round, then over/under extrusion will occur.
- Be mindful of any health organization requirements on the type of materials you're allowed to use for something that goes in your mouth. The same logic goes for ensuring you don't print the bristles in something that can mold.
I believe nylon is safe, at least in the US, but don't quote me on this.
I have had a go at doing something for a christmass tree using a drop loop technique. You could use the same method or somthing similar to try and create something that looks like toothbrush bristles, but I don't think you would want to try cleaning your teeth with it.