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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.

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  • $\begingroup$ Hello @J. Roibal, I noticed your question has been up for a while now. Have any of the answers below been able to solve your question? If so, would you mind accepting the appropriate answer. If not, what is missing so that we may help you further? Also, if you have figured it out on your own, you can always answer and accept your own solution. Thank you. $\endgroup$
    – StarWind0
    Feb 6, 2017 at 22:59

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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

https://www.engadget.com/2015/10/29/3d-printing-hair-is-as-easy-as-using-a-hot-glue-gun/

http://technabob.com/blog/wp-content/uploads/2015/11/3d_printed_hair_by_Gierad_Laput_Xiang_Chen_Chris_Harrison_1.jpg

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.

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  • $\begingroup$ One additional note on the formLabs (form1+) it can create features that are 25 microns but in my experience getting it to reliably print that is hit or miss, especially when they're printed extremely close together like on a bristle. $\endgroup$
    – Diesel
    Mar 6, 2017 at 22:58
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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.
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  • $\begingroup$ Just to add to this, even FDA approved printed materials would not qualify for in the mouth. As ones printer will not meet FDA standards. $\endgroup$
    – StarWind0
    Jun 20, 2016 at 5:36
  • $\begingroup$ @StarWind do you happen to know how the printed part would not meet FDA standards? Not even for natural PLA or Nylon? $\endgroup$
    – tbm0115
    Jun 20, 2016 at 13:59
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    $\begingroup$ We had a long conversation about it in the facebook group I run, 3d printing hobbyists. The issue comes down to your machine is not going to meet food grade / clean room standards. The member who worked in that space was very sure about it. The plastic will. $\endgroup$
    – StarWind0
    Jun 20, 2016 at 15:52
  • $\begingroup$ I thought it was silly, given the temps we are talking about $\endgroup$
    – StarWind0
    Jun 20, 2016 at 15:53
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    $\begingroup$ That's right! There's the issue with contamination in the nozzle and build plate setups (tape, glue, etc.), right? $\endgroup$
    – tbm0115
    Jun 20, 2016 at 15:53
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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.

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  • $\begingroup$ Could you maybe add a bit more detail? What's a "droop loop" technique? $\endgroup$
    – Tom van der Zanden
    Mar 6, 2017 at 20:01
  • $\begingroup$ Basically, the printer prints a line out from the model in thin air and then back to the model creating a loop or string of filament. $\endgroup$
    – user802599
    Mar 8, 2017 at 3:52

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