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3D print hair


How to create realistic hair for 3D hair printing

Introduction

3D printing is a very interesting topic for every startup and company, both for the creation of proof of concept, both for very specific unusual parts, such as 3d hair printing.

In our company, we use the 3D printer several times to print the most varied things: we create and print custom cases for boards, joints for robotic parts, humanoid robot parts, gadgets, etc … For example, take a look at our article about an IoT application with a custom case: https://www.makarenalabs.com/nebul-iot-a-simple-embedded-smart-device-for-greenhouse/

We also use different materials for different purposes, for example:

  • PETG for strong large models;
  • TPU for soft models;
  • UV resin for small, extremely precise, and detailed models.

For each model, there is the right material.

We were looking for new printing techniques when we had discover 3D printed models of animals or people with realistic hairs or fur. So, we decided to replicate this type of model and, not finding any tutorial about it, we decided to do it ourselves.

Mesh creation for 3d printing

First of all, we need a head or a part of the body to create hair. For the majority of the projects, we use Blender.
The starting mesh must be manifold, with correct normals, avoiding faces without thickness, otherwise, it is impossible or very difficult to print it.

I do not recommend using a particle system and converting it into a mesh (it is extremely heavy) for the construction of the entire mesh.
The starting point to create a solid object that represents hair could be a cylinder, a cube extruded in a single axis, or a similar mesh. To speed up your work you can use a single “hair” mesh to create two hair. Each hair is crafted individually.
A few points of the procedure before we begin talking about the starting mesh (the head to be clear):
– first, the mesh, as I said before, must be manifold
– then, the mesh must need a few supports to be print
– then, the mesh mustn’t have graphic obstacles around the affected area, like ears too massive, hollows or concave areas, etc…
– finally, the base on which rests must be stable.

The hair creation

Let’s begin from the first single hair:
– I recommend you to use, for the mesh, a cylinder shape or parallelepiped shape
– the mesh length will be what you want, but remember that once settled the hair length, it could cover some detail about the head mesh.
– I recommend you a mesh thick about 0.5 millimeters but it depends on how much your printer is able to create thin objects.

For a full head of hair, we use the “spin tool” in edit mode. For example, in our demo model, we have rotated the model in a way that will be horizontal, and in the spin tool settings, we used a dozen steps in the Z axis.

You have to duplicate the hair mesh enough to cover the head.
After that, you have to delete the parts of the mesh that cover the details of the head.
Remember: all of the hair mesh must be horizontal to the head because then we have to create the support for the hair.

in conclusion, you have to use unite all the hair with the head: add a boolean modifier and, with union option, connect the hair to the head.

Supports for 3d printing

we will create some supports that will hold up all of the hair mesh. It’s very easy: you must create a hollow cylinder with a thickness of roughly 2 – 3 millimeters that surrounds the entire structure and encompasses 1-1.5 millimeters of the end of hair mesh.

If you need to print your model with additional supports, you will, unfortunately, do it by hand with Blender.

in conclusion, you have to unite the cylinder with the other mesh.

Hairstyle

To finish your hair head and create a styling, you’ll need to do one of these options:
– A thermo-gun (best choice)
– An hairdryer (safer choice)
– Very hot water (we have never tried it)
Arm yourself with special thermal gloves (don’t do like the video) and an object similar to a hairbrush for combing the hair.
Now, melt slowly the hair (try to not melt the head), make some pauses, and comb continuously the hair to keep the shape.
If you want to use the hot water, put your object in a basin and pour the hot water over the head.
Let me know if you manage to do it!
Enjoy

3D Printed Hair: Can We Print Transplantable Hair Follicles?

3D printing has been able to mimic the look of hair for a while, like in the lion print seen below. By printing thin filament layers onto a wall of plastic, and then melting and styling it with a hairdryer, the desired hair-like look can be achieved.

However, most balding men can’t rock the PLA plastic hair look (who can?), so we need a better alternative when it comes to 3D printed hair for transplants.

What we haven’t been able to do is 3D printed hair grafts that can grow human hair.

Wigs and toupées offer solace for many with receding hairlines, but for a lot of people, the loss of confidence goes beyond the aesthetic. Thinning hair or complete hair loss is a huge issue for thousands of men and women all over the world.

3D printed hair offers a hopeful solution to this issue, and breakthroughs have already been seen across the scientific community.

Here, we will look at the history of 3D printed hair, and what it means for the future of transplants and grafts.

Early Research into 3D Printed Hair

While making filaments look like hair is a simple enough process, the first notable breakthrough in usable 3D printed hair was in 2016, when L’Oreal took a new step in their 30-year-long research into artificial biological tissue by partnering with 3D bioprinting company Poietis.

This was big news at the time, as the combination of L’Oreal’s expertise in hair biology and Poietis’ breakthroughs in bioprinting brought with it exciting potential for viable 3D printed hair.

In 2017, Poietis used this research to further its existing partnership with German chemical company BASF to help develop 3D printed skin as a means to develop cruelty-free testing of drugs and cosmetics.

In 2019, Poietis CBO Bruno Brisson claimed:

“I can confirm that we have gone successfully through interesting validation steps over time on a project that is a real challenge since no one has so far managed to bio-print the most complex organ of the human body: the hair follicle!”

He further cited that there would be “some scientific communication within the next months as an outcome of this collaborative research agreement.”

The results of this research were kept relatively quiet until 2020, when L’Oreal announced the findings of their research into mimicking embryonic cells to cultivate 3D printed hair follicles that could be used to ‘clone’ human hair.

L’Oreal has been making strides in hair growth therapies using what they call follicle culturing, which involves growing hair from follicles in vitro and making them ready for transplant, rather than actively encouraging natural hair growth.

Columbia University Research

It’s important to note that 3D bioprinting hair follicles, and creating an environment/skin they can grow on, are two completely different things.

In researching the viability of 3D printed human hair, researchers at Columbia University looked to mice as they, among other animals, seem to have natural inhibitors to stunt fur growth after a certain length.

Specifically, they wanted to see if they could revitalize what they called ‘dormant follicles’ into promoting hair growth where none was occurring. In essence, they wanted to see if they were able to trick the body into creating more fur where it otherwise wouldn’t have grown at all.

They found that they could stimulate hair growth on grafted mouse and rat skin. However, the same process was unsuccessful in human trials.

They reported that they believe this happens due to cell loss as skin grows, concluding that these follicle revitalization techniques won’t work in humans in the same way they work for rats.

Dr. Angela Christiano, a specialist in regenerative therapies for skin and hair in Columbia University’s Florence and Herbert Irving Centre for Dermatology and Skin Cancer Research, said: “Cells from rats and mice grow beautiful hairs, but for reasons we don’t understand, human cells are resistant. ”

Instead, they looked into 3D printing a mold that replicates the conditions in which hair follicles grow. The skin itself grows around the mold, replicating how human hairs grow.

Within these molds, the cells have a structure to follow. Cells can be placed within this mold, as well as keratin and collagen gel. The follicles would float on the gel in these microwells, which mimics the way they would grow on the human body.

The reason this is possible is down to newer technology within 3D printers. Whereas previously, they may have attempted to use techniques like soft lithography.

This method is used to create stamps and molds using elastomeric materials, hence the term soft. The new techniques “allowed for creation of structures with high aspect ratios”. The ratio for a human hair follicle is different from that of a rat, so that’s something that will make a clear difference.

They observed hair growth after around three weeks. Hairs even grew at different angles, replicating how human hair naturally grows.

Three weeks may seem like a long time to grow a small amount of hair, but this is a massive step towards helping people who suffer from hair loss, as this process encourages further hair growth rather than simply transplanting existing hairs.

Dr. Christiano is keen to perfect research into 3D printed hair follicles as a means to treat all kinds of hair loss, from receding hairlines to those suffering from severe burns.

The Benefits of 3D Printed Hair Follicles

The obvious use for the growth of hair follicles on bioprinted skin is in hair transplants. Currently, FUE hair transplants involve taking hair follicles from the back of the head, where men do not commonly lose hair, and transplanting them to the area of the head where hair loss has occurred.

However, regardless of how much hair can grow, the number of follicles is roughly the same in every human being, this means that there is only a finite amount of follicles that can be transplanted. Anyone without enough transplantable hair follicles could ideally instead have hairs 3D printed and transplanted instead, leaving their remaining hairs intact.

In addition, any removed hair follicles leave scars on the back of the head that can itch, and remain visible for a long time. Because of this, many people choose to avoid going through the process of hair extractions. 3D printed hair follicles could theoretically remove the issues of these scars and the need for painful hair extraction.

As well as creating artificial skin and hair for cruelty-free testing of cosmetic products and drugs, the ability to 3D print hair follicles could also aid research into the physical and psychological reasons for hair loss, and further studies into prevention methods.

The Future of 3D Printed Hair

While current research into 3D printed hair follicles looks promising, we’re nowhere near being able to 3D print hairs that grow and act like our hairs do.

However, research has shown that functioning human hair follicles can be 3D printed. This breakthrough displays exciting and vast potential for the future of the cosmetic industry.

The science still has a way to go, but 3D printed hairs could offer a solution for the millions of people who have lost their hair through various means, be they genetic or through an accident. These future treatments have the potential to be life-changing via massively increased confidence and self-esteem in those for whom hair loss has negatively affected their lives.

Though difficult, 3D printing human hair goes far beyond the original plastic or wooden 3D printed hairs hobbyist projects use, and we look forward to seeing further advancements.

Other articles you may be interested in:

  • 3D bioprinting and 3D printed organs – top projects
  • 3D printed kidneys
  • 3D printed hearts – how long until we can 3D print a heart?
  • 3D printed livers – feature story

Problems, defects, 3D printing errors and solutions

Often during the operation of a 3D printer, problems may arise due to which defects appear on the finished model. Or instead of a neat product, plastic noodles suddenly appear on the table.

In fact, the causes of defects can be conditionally divided into 2 types - these are physical and software.

Physical ones are those that arise due to problems with the mechanics or any other causes that can be eliminated physically. These include problems with printer mechanisms (belt tension, backlash), clogged or deformed nozzle, incorrect table geometry, etc.

Software - these are defects that occur due to incorrect slicer settings or, less often, errors in the printer firmware. For example, incorrectly selected print speed, retract settings, incorrectly selected temperature for plastic, etc.

Very rarely, the problem may lie in the wrong or “flying” printer firmware (although usually the printer simply will not start then), overheating of some boards during printing, etc. These are rather special cases, so we will not consider them.

Model peels off or does not stick to the build plate

This is the most common 3D printing problem. Every 3D printer has had a case when the first layer treacherously rolls, clinging to the extruder, or the most offensive - when it tears off a partially printed model from the table. The first layer must stick tightly otherwise nothing will be printed.


Gap between table and nozzle 9 too large0023

This is the most common reason. You just need to set the correct gap between the table and the nozzle.

Modern printers often use an auto-calibration (auto-leveling) table system or an auxiliary table leveling program. To calibrate such printers, use the instructions. If there is no manual, it can be downloaded from the manufacturer's website.

If you have a simple printer without auto-calibration, a self-assembly or KIT kit, use a probe or a piece of paper folded in half to calibrate. The probe should be slightly pressed against the table by the nozzle. Before calibration, the table and extruder must be heated. Align the table surface over each adjustment screw (there may be 3 or 4) in turn, and only then check the center point.

If you're having trouble getting your table surface perfectly level, try raft printing. Raft is a thick substrate in several layers that is printed under the model. It will help smooth out the slight curvature of the table.


A small cheat sheet to determine the correct gap on the first layer

Plastic with poor adhesion

Some types of plastic, due to various reasons, such as large shrinkage, do not adhere well to the surface of the printing platform. In this case, try using stickers or special 3D adhesives to improve adhesion between the table and the first layer of plastic.

In the early days of 3D printing, there were experiments with different homemade 3D adhesive recipes. ABS diluted in acetone, BF glue, sugar syrup and even beer. Some experiments have been successful. Until now, some enthusiasts use some types of hairspray or glue sticks as 3D glue. But still they are inferior in their properties to industrial 3D adhesives.

Some types of high temperature plastics with a high percentage of shrinkage (ABS, Nylon, etc.) may peel off the table during printing. This is due to uneven cooling and “compression” of the model (the lower layers have already cooled down, but the upper ones have not yet). For such plastics, it is imperative to use a 3D printer with a heated table and a closed case.

Plastic temperature too low

The hotter the plastic is when it exits the nozzle, the better it will adhere to the print bed. It is better to print the first 5-10 layers at a higher temperature (+ 5-10 degrees) and turn off the blower fan.

Wrong first layer settings (speed and thickness)

A thicker layer sticks easier, so the standard first layer is 0.3mm thick. With an increase in print speed, the heating block may simply not have time to heat the plastic to the desired temperature and it will stick to the table worse. Before printing, check the speed and thickness settings of the first layer in the slicer.


A lot depends on how the 3D printer prints the first layer. Try to control the printing of the first layer and only then leave the printer to work alone.

Plastic does not choke from nozzle

The printer has already begun to print, but the print table remains empty. Or part of the model did not print.


Clogged nozzle

In 3D printing, a nozzle is a consumable. The nozzles are clogged or worn out (frequency depends on the type of plastic). The simplest thing is to replace the nozzle. But if there was no spare at hand, you can try to clean the old one. To do this, there is a whole set of thin needles. Or you can heat a clogged nozzle above the melting point of the plastic and “burn out” the blockage. But later it is still better to replace the nozzle.

Low temperature nozzle

You need to increase the temperature of the extruder in the slicer settings or check the thermistor and heating block. Sometimes the thermistor may not read the temperature correctly due to a malfunction or incorrect 3D printer firmware settings.

If the problem occurs after replacing the thermistor - contact the manufacturer or read articles about PID tuning.

Empty extruder

As the extruder heats up, plastic begins to ooze out of the nozzle. Because of this, the extruder may start printing half empty. Because of this, part of the first layer is not printed. You can push the plastic manually by simply pushing the bar into the nozzle. Or solve this problem programmatically - in the slicer, add a contour print around the model (one line).

Some manufacturers and 3D enthusiasts add a line print on the edge of the table at the beginning of each GCode. This is done so that there is plastic in the nozzle by the time the model is printed.

Feed mechanism does not push through plastic

The plastic pushes the feed mechanism to the extruder - a motor with a special pulley put on the shaft. If for some reason the plastic is not pushed through (nozzle clogged, extruder temperature low, etc.), then the pulley “gnaws” through the bar. You need to push the plastic bar with your hands or cut off the damaged piece.


Elephant foot

The first layers of the model are wider and protrude beyond the boundaries of the model. This is due to the fact that the upper layers put pressure on the first ones that have not yet cooled down and flatten them.


High table temperature

Due to the too high temperature of the table, the lower layers remain soft for a long time. Try lowering the table temperature. It is better to reduce gradually (in increments of 5 degrees). You can try to turn on the blower when printing the first layers.

Small gap between nozzle and platen

If, when printing the first layer, the nozzle is too close to the table, then excess plastic will be forced out. After a few coats, this will not be as noticeable, but can lead to the effect of an “elephant's foot”.


Plastic re-extrusion

When too much material is squeezed out of the nozzle, the walls of the model are not smooth, but bumpy, with sagging.


The solution is software - in the settings of the slicer, you need to set the material feed rate (fluidity) to a lower value. The average value is 95-98%.

It is worth checking the diameter of the rod. If its size is greater than 1.75, then the plastic will be squeezed out more than necessary.


Plastic underextrusion

The plastic is squeezed out too little, because of this, gaps may appear between the layer. The finished model will be fragile and fragile.


Wrong thread diameter

Check the filament diameter in the slicer settings. Sometimes, instead of the popular 1.75, the default is 2.85.

Incorrect feed factor settings

Check the fluidity settings in the slicer. The average should be 95-98%.

Clogged nozzle

Something could get into the nozzle and partially block the exit of the plastic. Visually, the plastic will choke from the nozzle, but in a smaller amount than necessary for printing.



Hairiness or cobwebs on finished model

Thin threads of plastic protrude from the outer wall of the model (most often on one side). The defect appears due to the flow of plastic from the nozzle during idle movement.


Insufficient retract

A retract is a slight pull of a plastic filament from an extruder. Due to the retract when the extruder is idle (from layer to layer or from model to model), heated plastic does not drip from the nozzle. For some flowable plastics (eg PETG) the speed and amount of retraction must be increased.

"Hairiness" can be easily removed by grinding or cutting off the threads with a sharp scalpel.

High temperature extruder

The higher the extruder temperature, the more fluid the plastic becomes. It is important to find a balance so that the plastic is not too liquid and sticks well in layers.

In the selection of the optimal extruder temperature, a test model - a tower - helps a lot. It clearly shows how plastic behaves when printed at different temperatures.

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Temperature test

Top "perforated" or uneven

The top of the model is bumpy or with holes. The problem may arise if the top of the model is flat. For example, like a cube.


Insufficient airflow

When printing the top plane (cover), the plastic does not have time to cool down and remains too liquid. Because of this, the threads are torn and holes are formed. Increase the fan speed on the last layers.

Few top layers

The top of the print may be too thin and deform as a result. Check slicer settings. The number of upper layers is not recommended to be set less than 6.

Low percentage of filling

If the infill percentage is too low, then the top layer will simply have nothing to rely on. Increase the fill percentage in the slicer settings.

Model deformation

Some parts of the model seem to have melted in some places or on one side. The problem most often occurs when printing with PLA plastic. The defect appears due to the fact that the plastic does not have time to cool and deforms.


Insufficient airflow model

Turn the fans on to maximum. If their power is not enough (in some printers, the fan is located only on one side), you can put a regular desktop fan and direct it to the 3D printer table.

Small model

Small models are difficult to blow well. Try to print small items alongside larger ones, or place several identical models in different corners of the table. So the plastic will have more time to cool.

Layer offset

Layers shift along the x or y axis during printing.


Print head jam

Turn off the printer and try to move the extruder along the x and y axes with your hands. The extruder must move freely. If there are jams, check the mechanics of the printer. Bearing wear or the curvature of the shafts may be to blame.

Electronics overheating

Sometimes electronics problems can be to blame for misaligned layers. The most common cause is overheating of the drivers or too low current exposed to them.

Table top is loose

This is most often seen in 3D printers with glass. During printing, the nozzle may hit the model and move the glass slightly. Before printing, check if the glass or other printing surface is well fixed on the heating table.


Skip layers

Small holes are visible on the print, or the shell of the model is not continuous.


Teflon tube deformed

There are 2 types of thermal barriers - all-metal and with a Teflon tube. If overheated, the Teflon tube may deform. Plastic will pass through it, but in a smaller amount.

Low extruder temperature or high print speed

If the extruder is not heated enough, then the plastic will not be liquid enough and simply will not have time to be forced through the nozzle. The higher the print speed, the higher the extruder temperature should be.

Sometimes the outer walls print well, but the infill is “torn”. In this case, slow down the infill print speed in the slicer.

Model bundle

Cracks form on the surface of the printout during or after printing. Cracks can be large or very small. Most often, this problem occurs with plastics with a high percentage of shrinkage - ABS or Nylon.


Sudden temperature difference (if model delaminates during printing)

With a sharp temperature difference (for example, a draft), part of the model cools down faster. This leads to uneven shrinkage and incorrect distribution of internal stress. For plastics with low shrinkage, this is not critical. But if the shrinkage percentage is more than a few percent, the model may burst in layers.

For printing with such plastics, it is recommended to use a printer with a closed housing. If this is not possible, try to avoid drafts and sudden temperature changes in the room where the 3D printer prints as much as possible.

Print temperature

Due to too low printing temperatures, the layers may not “stick” well to each other. Raise the print temperature in the slicer settings.

Hardening (if the model cracks after printing)

Sometimes cracks appear on the model a few days after printing. This is due to uneven distribution of internal stress after cooling. You can try to “harden” the finished product.

For hardening, the model is placed, for example, in an oven, and heated to the softening temperature of the plastic. After that, the heating is turned off and the oven is left to cool slowly with the model inside. Due to this, the stress inside the print is distributed more evenly. But accuracy is very important in this method - if you make a little mistake with the temperature, the finished product can “float”.

Ringing

In places where the extruder changed direction, ripples are visible. Most often it looks like a shadow around the “sharp” protruding elements of the model.


Mechanical problems

Sometimes the problem occurs due to extruder play. Check if the extruder mount to the rails is loose. Be sure to check the tension of all belts.

High print speed or high accelerations

Moving the extruder too fast can cause vibrations that cause ripples on the wall of the model. The lighter the weight of the extruder, the less noticeable the ripples will be. To get rid of ringing, simply reduce the print speed in the slicer settings.

Slits for thin-walled models (not solid shell)

The thin wall of the model is not solid, but consists of two thin walls with a narrow gap between them. This problem is often faced by fans of printing "cutting" for baking.

Left model with wall defect, right without

Wall thickness and nozzle diameter mismatch

If the wall thickness is 1 mm, and the nozzle diameter is 0.4, it turns out that for a solid wall, 2 nozzle passes are few, and 3 are already many. The result will depend on the slicer algorithm, but most often you will get 2 walls with a thin slot in the middle (the slicer cannot change the wall thickness). The solution to the problem may be a slight refinement of the 3D model or the use of a different slicer.

Algorithms for calculating 3D models are constantly being improved and refined, and now this problem is less common.


When modeling, take into account not only the thickness of the nozzle, but also the percentage of “overlapping” of lines on each other. If you have a nozzle with a diameter of 0.4 - make the wall in your model not 0. 8, but 0.7 - 0.75.

Wrong model geometry

When instead of a circle you get an oval, and instead of a square you get a semblance of a rhombus.


The main reason is malfunctions in the mechanics of the printer. Be sure to check:

Belts

Check belt tension in x and y. Belts stretch over time and may need to be tightened or replaced. Each 3D printer has its own way of tightening the belt. If the belts are slightly stretched, you can tighten them with the help of a "spring".

Loose pulleys, etc.

Check if all bolts and nuts are tight. Are there backlashes. Pay special attention to tightening the pulleys located on the motors along the x and y axes.


Sagging of some parts of the model

Some parts are not printed, broken, or instead of a neat surface, a swollen plastic snot is obtained.


No support for overhangs

A 3D printer cannot print in the air, so if there are overhanging elements in the model, you need to set supports - supports. The slicer can set the necessary support itself, you need to check the appropriate box in the settings.


When printing with soluble support, you can set the gap between the model and support - 0. This will make the surface smoother. If the support material and the model are the same, you need to add a small gap. Otherwise, it will be difficult to separate the support from the model.

Split model

Sometimes the supports can take more plastic than the model. In this case, to save material and time, it will be more convenient to cut the model. If you have more than one 3D printer, then the model will print several times faster.

When cutting the model, you can leave grooves or mortgages so that the pieces of the model are connected without displacement.


Totals

In this article, we talked about the most popular 3D printing defects and how to solve them. Don't be intimidated by such a long list. Some problems are rare and you are unlikely to encounter them.

There is a list of problems that arise due to the design features of a 3D printer, so try to choose a printer that suits your needs. To do this, you need to understand what products and what material you need.

Problems associated with printing algorithms are quickly eliminated by software developers.

Do not be afraid of possible difficulties and each print will be successful.


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