What is a Support Structure?
Before we go into too much further detail, we need to cover what these materials are even used for. PVA and HIPS are both materials used for creating support structures. They are needed when you want to create intricate geometric designs such as overhangs, bridges, or any figure that works against gravity. Usually any structure that goes above a 45-degree angle might need a support structure.
Support structures act as a base for your main build material to rest on until it becomes fully set and dry. The absence of a support structure could simply cause your print to collapse and the design you expect for your print cannot be achieved.
Here are some of the important specifications that support structures should have:
Ability to be dissolved easily.
- There are many types of plastics that have this feature, but PVA and HIPS are the most commonly used.
- It’s best to do some research on what solvent works best for your support.
Compatibility with the build material
- It’s important to know that not all plastics work well with each other.
- For example; HIPS cannot work with PLA because its solvent is known to chemically react with PLA. PLA could be damaged during the process of dissolving HIPS.
Now that you know the importance of having a support structure, let’s compare two of the most commonly used support structures in 3D printing.
What are the Specifications of PVA and HIPS?
What are the Advantages of PVA?
Due to its ease of use, PVA can be ideal for you if you plan to make complex geometric structures. Here are some of the advantages when using PVA:
Water as solvent
- Because it is water-soluble, the process of dissolving this support material makes it a lot easier.
- You don’t have to go purchase a solvent for PVA because water is all you need to dissolve it!
How to dissolve: Submerging your print in tap water will do the trick. You won’t even have to worry about your build material reacting because it isn’t acid-based.
- If you’re concerned about your health or even for the environment, then toxicity should be the last thing to worry about when using PVAs as they are essentially considered to be non-toxic and biodegradable.
Heat bed may not be necessary
- Most plastics need heat beds to prevent them from warping as it often is the case when outer edges tend to cool down faster than the inner part of the plastic.
- Heat beds will act as the “adhesive” for the plastic that prevents it from moving and compromising the whole works.
Compatible with several build materials
- Also due to its water solubility, it works well when you want to use PVA together with a different build material.
- In order to use two materials, you need a dual extrusion printer.
Low temperature requirement
- The lower temperature requirement for PVA makes energy consumption lesser.
What is a Dual Extrusion Printer?
In simple terms, an extruder is an essential part of a 3D printer where it expels the filament or material used such as a PVA to make the object. Typically, a 3D printer only has a single extruder, but many are also equipped with two extruders.
PVAs can be made for dual extrusion printing when it is used as a support material for PLA (Polylactic acid).
Drawbacks with PVA
- PVA can be on the pricier end of the spectrum.
- The price range can be somewhere between $30 to $40. This one found on Amazon that is relatively cheaper compared to others.
- Because PVA is hydrophilic in nature, it tends to react badly to airborne moisture when not in use.
- It’s important to store PVA in a dry leak-proof container to preserve its quality.
- A desiccant may be added in the container to achieve optimal storage condition.
- It’s true that PVA is easy to dissolve given the fact that you only need water as the solvent, however, the process could take up to several hours to a day.
- PVA, when subjected to higher temperatures, tends to ooze out due to its low melting point causing the nozzle to jam and clog.
- It’s best to clean the nozzle after each use to preserve the quality of your printer.
- Some 3D printers are equipped with ooze shields where you just need to activate it in settings.
Ways to Speed Up Dissolution of PVA
While it could take 18 to 24 hours to dissolve PVA, there are several ways that you can speed up dissolution:
- Lukewarm water works best. Don’t use hot water as this can damage your build material especially PLA.
- How to dissolve: Simply submerge your print in a clean container with lukewarm water along with gentle agitation as this may help speed up the process.
Sonic bath cleaner
- If your 3D print is small enough to fit in a sonic bath cleaner, this can be a convenient option for you.
- Ruiz Brothers recommends running at least a dozen 2-minute cycles to completely wash away PVA.
Pliers or spudger
- After submerging your print in warm water for at least 10 minutes, you may check to see some parts that are starting to come loose.
- Use pliers or spudger to remove some of the loosened parts.
- Care must be taken when removing some parts mechanically. Don’t force it if it doesn’t come off as this can damage your print.
Don’t forget to rinse off with running water as the last step to clean up your print. Pat dry with a dry paper towel afterwards.
When to Choose PVA as Support
PVA is a great choice if you decide to use PLA (Polylactic acid) as your build material. PVA and PLA make a great combination due to their similar temperature requirements ranging from 190-220°C. You won’t have to worry about damaging one material or the other, which frequently occurs when two materials have different optimal temperature.
While there are other build materials aside from PLA that work well with PVA, it is best to do your research first. Typically, each manufacturer or brand will specify what support filament works and what doesn’t. For instance, Ultimaker claims that their PVA has reliable adhesion to CPE (Co-polyester) and nylon. Thus, it is always best to check what the brand recommends.
Why Should You Choose PLA as Your Build Material?
PLA is great for those who are new to 3D printing simply because of its ease of use. If you want to print an intricate model design but want to start out easy, this is your best choice alongside PVA.
In addition, PLA is non-toxic and biodegradable just like PVA. Thus, it is safe for both your health and the environment.
What Are the Advantages of HIPS?
A regular polystyrene breaks easily, so to address this problem, HIPS was created as the “love child” of polystyrene and polybutadiene rubber. HIPS is a waterproof plastic commonly used in 3D printing due to its resilience, durability, and cost-effectiveness.
Furthermore, HIPS is relatively cheap compared to PVA. Price ranges from $8 to $20 on various websites like Amazon. This is almost half the price of PVA! So, if your goal is to create many prints, then you can get more with HIPS.
Aside from the fact that HIPS acts as a great support material, HIPS can be used as a build material on its own.
Drawbacks With HIPS
- As it is insoluble to water, you will need to purchase a solvent called limonene to dissolve HIPS.
- Limonene is the oil component of citrus fruit peels.
- This can be reactive to many types of build materials, so it is imperative to know what material can withstand the properties of limonene.
To dissolve: Airwolf3D suggests submerging your print in a 1:1 mixture of limonene and isopropyl alcohol. A sonic cleaner may also do the trick.
Emission of toxic fumes
- When HIPS is heated, it emits noxious fumes called styrene.
- According to U.S. Environmental Protection Agency, acute exposure to styrene results in irritation of the eyes, skin, and digestive system. Long term or chronic exposure could affect the central nervous system where you could experience fatigue, headaches, depression, and more.
- It is best to have good ventilation in your area when printing.
Higher temperature requirements
- HIPS require a high nozzle temperature of up to 240°C and a bed temperature of up to 110°C.
- There aren’t many other build materials that can withstand the higher temperature other than ABS.
Poor bed adhesion
- Bed adhesion may be compromised because of the higher temperature requirements.
- The cooler the temperature, the less likely for plastic to adhere to the build plate.
Poor bed adhesion causes the print to move constantly resulting to instability and inaccuracy that could ruin the whole structure.
- The good news is that there are several ways to remedy this problem.
How Do You Resolve Poor Bed Adhesion?
Bed adhesion is influenced by three main factors: temperature, bed material, and surface coating. Here are three ways you can address poor bed adhesion:
- The higher the temperature, the more likely it is for plastic to adhere.
- Although pricey, heat beds will keep the plastic from moving and warping by constantly warming both the outer and inner parts of the plastic.
- This tape was essentially created to be used in space as it can withstand high temperatures.
- To prevent air bubbles forming during application, Matterhackers recommends spraying the entire surface of the bed plate with a soapy mixture before laying the tape on the build plate.
- The soap will allow you to position and adjust the tape before it could actually stick.
- Use any flat surface such as a ruler to start pushing away the soap working at the center first moving towards the edges.
- Let it dry completely and then spray over hairspray.
- This is probably the most economical method to improve bed adhesion.
- There are many varieties of glue that you can use to help HIPS adhere more to the bed; from Elmer’s glue to Wolfbite glue, they can provide extra adhesion.
When to Choose HIPS as Support
HIPS is an excellent choice if you plan to use ABS (Acrylonitrile butadiene styrene) as your build material because of their rigidity and durability. While both share an optimal hot temperature range of 220 to 240°C, the main reason why they are a great combination is that ABS does not chemically react nor corrode with limonene, the chemical solvent for HIPS.
One thing to remember when using both materials is to work in an environment with adequate ventilation as ABS emits a slight odor during printing while HIPS emits noxious styrene fumes.
Why Should You Choose ABS as Your Build Material?
ABS used to be a popular choice back until recently when PLA became more popular for its ease of use. Nonetheless, here are two reasons why ABS is the right material for you:
- ABS is tough and has a high-impact resistance making this an optimal choice for 3D prints that often go through extra usage. In fact, LEGO blocks are made of this material.
- Just like HIPS, it is also cost effective. So, if you’re on a budget, this could be the right material for you.
- Be aware that it is more difficult to print, so if you fail, you might end up spending a lot more.
Durability and cost-effectiveness are only two of the many advantages for using ABS. However, one thing to keep in mind when using ABS and HIPS is that they are prone to warping. Don’t fret because there are several ways to keep your 3D print from warping.
How to Avoid Warping
Normally, thermoplastics expand when heated or in a liquid state, and shrinks when cooled down. A common occurrence that results to warping is when the extruded plastic that comes in contact with the build plate begins to cool down while the other parts above it is still hot. This is usually evident on the edges or around the corners.
Here are ways that you can do to avoid warping:
Heat bed plate at least 10 minutes before starting to print
- This keeps the base of the model from uneven cooling.
Build plate must be leveled
- It is necessary for the bed plate to be leveled or in parallel with the direction travelled by the nozzle.
- Many 3D printers come with a setting of auto-leveling.
- It is always good to check each manufacturer’s instruction as every printer is different.
Set cooling fan correctly
- Set it too high and your model could start to warp.
- As much as possible, set the cooling fan to its lowest setting, or better yet, turn it off completely.
How to Fix Warping
Warping, in some cases, may be reversible. All you need is a hair dryer to blast warm heat to your print and move the dryer around to distribute heat. Once you feel the plastic starting to soften, you may want to try bending it back. If this doesn’t work, then I’m afraid you would need to reprint your model again.
The choice between PVA and HIPS ultimately depends on a variety of factors including the build material to be used and what structure to create. PVA is used by many 3D printing enthusiasts because of its solubility in water and ease of use whereas HIPS is often used in support of ABS for those who seek for durability and rigidity.
While there is no single characteristic that outweighs one over the other, it is always essential to know what build material works best because using the wrong combination could just ruin the entire 3D print.