3D prints are not the same as resin cast models....

Just saying they are resins, and should be in the same category, is the same as saying they are all plastic models so resin cast models should be lumped in with Breyers. As a consumer, you should become familiar with how those manufacturing process and materials differ.

This article is not written with the intentions of getting people to not buy 3D prints. It is written to show the differences between resin cast models and 3D printed ones. There are bad sellers and there are great sellers... either way there are important points to know about before a consumer can make an informed decision and consider any risks there may be.

I have been directly asked to delete this because the person was fearful it would hurt their business. As a seller of cast resin models I could very well say that same thing in return... don't you think that the recent flood of 3D prints could do the same thing to sellers of cast models? This should never be a concern if you are doing quality work and genuinely care about your customers.

I sell 3D prints (micro and smaller only) and also use them as prototypes for casting. I started in-house printing in 2012 (3D modeling in 2009)... 3D printing for 12 years. At that time I do not know of anyone else in the hobby with in-house printing although there was one person (that I know of) getting their models scanned and a prototypes printed for casting, with an industrial service. An article on how I did this printing process was published in Equine Collectibles magazine when we scanned and printed Tadpole. Prior to that I did my own horses. My partner is one of the very first people in Italy to work with 3D modeling and printing years ago. We are an older crew with many years of experience. And so, yes, we do have the knowledge base.

I am saddened by the amount of greed, plagiarism, and horrible customer treatment I have seen with print farmers. I absolutely do not think everyone is like that. My intent is to protect you by simply making you aware of things you should know when you ask about your purchase. And things you should consider before investing in something you may want to enjoy for a lifetime. If anyone raises a stink about that, then I would have to ask myself why. Those who sincerely seek the truth should not fear the outcome.

There are exceptions to anything and everything. The entire point of this article is to inform hobbyists of problems that can happen so they will know what to be aware of. Some sources have been provided, however Google is open to everyone. There are almost always opposing views on any subject. Some things are solid fact, however.

 

This is a 3D rendering of two digital models

 

When testing materials... remember that thin areas on model horse have WIRES and freshly printed 3D resin will always be the most flexible at that time. Typically, when castings break there will be cracks and not a total separation as the wire still supports it. 3D print resin never stops curing throughout its lifespan. To demonstrate how the materials age, would require presenting it in the same conditions your model would be under… and if you want to demonstrate age it would need to be aged material.

"Drop" Tests

  • This article centers around longevity. A drop test made with a freshly printed model has no bearing on this subject. A printed model is at its strongest and most flexible when freshly printed.

  • This article centers around the average shape of a horse; four legs of common thickness (not a draft horses which would have thicker legs and body), average shaped tails - all in a normal position.

  • You would need to know if the test model has several years of age, if it is hollow or solid (how thick at the walls on a hollow model) and if this is the same thickness you would be purchasing, if four legs and a tail are exposed as in a position you may be purchasing. There are many variables. Just make sure what you are seeing directly applies to what you are wanting.

Like any physical object, the lifespan of a 3D print is not infinite. Over time, prints may experience natural degradation, especially if exposed to external factors. However, proper care and maintenance can significantly extend their lifespan. https://medium.com/@hocpublishing/unveiling-the-longevity-of-3d-prints-how-long-will-your-creations-endure-ed636b5621bd

MATERIALS
Resin Cast Models: Castings have enduring strength due to stainless steel wire support throughout the model. Resin castings are compatible with materials and customizing/repair procedures that we are familiar with.

3D prints: 3D prints do not contain any critical stainless steel wire support and are extremely susceptible to environmental changes and natural aging of the layered material. 3D prints never stop curing throughout their lifespan.

There have been enough broken legs to see that they are not made with wire support.

These resources are shared due to the amount of uncured prints I have seen complaints about. Do not touch them with your bare hands... https://www.wevolver.com/article/is-uv-resin-toxic-risks-and-safety-measures-explained

https://innotechtoday.com/how-to-use-3d-printing-resins-safely/#:~:text=Long%2Dterm%20exposure%20to%20resin,increase%20the%20risk%20of%20cancer.

Resins come in many forms, including acrylate-based or epoxy-based resins to name a couple. Tougher industrial resins can have a tensile strength of up to 8,000psi, making them extremely durable. However, more commonly used resins such as the Anycubic 3D Printer Resin has a tensile strength of just 3,300psi. https://3dprintspy.com/guides/are-3d-printed-objects-durable/?fbclid=IwAR10Uh7HahngF-10gG70wxQGy2rtN3QzSwcXIlUJ-QJcgQRHE-iHATr0XGo

PROCESS
Resin Cast Models: Resin cast models are made by combining two liquids that cure evenly and result in one solid material. Due to this process, there is no concern about the curing of the resin on the interior of the model. Bad resin is extremely uncommon and non-existent with well managed suppliers. Resin is mixed by the thousands of gallons and anything bad would require a noticeable recall. Older resin is managed by good companies and taken out of circulation before it expires. Anything else is the responsibility of the end user. Bad resin mixing has occurred. This is easily detected by uncured resin spots throughout the model (normally during the finishing process).

3D prints: 3D printed models are typically made by curing resin in thousands of layers. The curing of the resin on the interior of the model is a critical step. This takes additional time and care.

Not all printing processes produce high quality models...

  • Fused deposition modeling (FDM) 3D printers melt and extrude thermoplastic filaments, which a printer nozzle deposits layer by layer in the build area.

  • Stereolithography (SLA) 3D printers use a laser to cure thermosetting liquid resins into hardened plastic in a process called photopolymerization.

  • Selective laser sintering (SLS) 3D printers use a high-powered laser to fuse small particles of thermoplastic powder.

Weight distribution is a challenge, even with resin casting using metal rods (as with a horse on one or two legs and how the entire body weight is distributed). Does the form of your print have good weight distribution?

The distribution of weight within a 3D print can impact its longevity. Uneven weight distribution or stress concentration points may lead to weak spots that are prone to failure. Consider redistributing weight or reinforcing areas of concern to improve print durability. https://medium.com/@hocpublishing/unveiling-the-longevity-of-3d-prints-how-long-will-your-creations-endure-ed636b5621bd

 
 

QUALITY
Resin Cast Models: Resin casting was designed for artistic reproduction pieces. Detail on this reproduction is dependent upon the original sculpture that is used. Certainly the molding, the casting process, and age of the mold is also a factor but detail is never lost in a good reproduction.

A simple comparison of the best resin casting you can think of compared to a 3D print of the same quality will show the differences. The resin cast edition of Lucius that we completed at Seunta, is a great example. Emilia has super fine details on him like little wrinkles around the lips, ears and on the neck, all made with a fine needle. Every model in the cast edition captured these fantastic details.

 
 

3D prints: Mistakes, distortions and flaws definitely show up in 3D prints. Due to the material it is made with, these flaws are much more difficult to deal with.

Some 3D prints are printed with white resin in order to make them appear as resin castings. This can be misleading - ask questions...

  • Zoom in on photos. Makes sure the model has a face and nice detail. Are the ear and nose wrinkles there? Veining?

  • Purchase only when you can view actual prints and never purchase based up the screenshot taken of the digital model. The final model could look nothing like that picture as the processing of the file and quality of the printer plays a critical role in the final level of quality.

  • Is it made from the highest quality home printer available?

AGING
Resin Cast Models: Resin castings have been proven to last for many decades. After 30+ years, I still have unpainted resin cast models that are still super nice models.

3D printing was originally intended for prototyping. Charles ‘Chuck’ Hull is recognized as the ‘father of 3D printing.’ In 1984, he invented a method similar to 3D printing we have today called stereolithography. This method was developed for rapid prototyping. https://3dprintschooling.com/why-was-3d-printing-invented/

3D prints: The longevity of a printed model is very questionable. These models can show signs of decay at around 6 months. Some may last 10 years or so. It really depends on the environment, materials used on it, curing, and many other factors.

Natural degradation and brittleness with age is a common occurrence with prints. 3D prints are highly susceptible to environmental changes. Prints get brittle with age regardless of the finish, exposure to light, the resin used, or the printer it is made with. 3D prints often degrade over time by getting brittle with age, which can cause separation at the layers. Some prints simply come apart at the layers with aging and this happens underneath the finish.

I have had prototypes stored in a dark closet for several years. These were printed with highest quality process available, by a professional (outside of the hobby). I went to take one out to make a mold with and it had split. I picked up another one, made by someone else, and legs just popped off from moving it. There are many different things that could have caused this. I know other people that have seen the same thing happen with older 3D prints.

The following notations include links so that you may read the entire page within full context...

Be sure to use a UV resistant sealer! https://www.reddit.com/r/ElegooMars/comments/ety79t/my_prints_are_all_becoming_brittle_over_time_and/?share_id=pP7zw6j0S0UAEYuI8nEDZ&utm_medium=ios_app&utm_name=iossmf&utm_source=share&utm_term=5

Suppose you create 3D prints using high-quality materials and store them in suitable conditions with utmost care. These prints can last for many years to come. However, it further depends on the wear and tear or the stress it has to endure.

On the contrary, some 3D prints you create use low-end materials, such as plastic made using low-quality material. As a result, it will only last for a few years and start to degrade or break gradually.

Moreover, some environmental factors, such as exposure to moisture or sunlight and weather conditions, always come into play. https://www.pcguide.com/3d-printer/faq/how-long-do-3d-prints-last/

As a general rule of thumb resin prints should not be used as an end product. They are used to either create a mould for the final object or used as a fitness test where the dimensions and tolerances are tight. The cured resin is typically not 100% safe to handle...

Companies that release 3d printed with branded resins have custom formulas to match their printers. This is perhaps to ensure that the customer keeps coming back for the consumables. These custom formulations are most undoubtedly patented, however, it seems that they are keeping the formula a secret (until you reproduce it and they claim you've breached their patent). Due to the fact that the formula is unknown to the end-user no one can certify that the cured resin is 100% non-toxic and safe for contact with skin; either on the outside of the body or the inside. https://3dprinting.stackexchange.com/questions/15785/uv-degradation-of-uv-curable-resins

Resin 3D prints are aesthetically brilliant but have many shortcomings when used as a functional component. The materials are brittle, susceptible to Creep and UV degradation. As a company, we focus on providing durable, long-lasting 3D printed parts, therefore SLA does not currently fit into our business model. https://www.3dpeople.uk/3dpeopleuk-blog/2020/8/3/sla-removal

GUARANTEES
With any material that you choose for your model, be certain that a fair exchange or refund is available to you for either shipping damage or quality concerns upon receiving your model. 3D prints take much longer to process than resin castings and are also far more expensive to make. A good seller will back anything they make regardless of these considerations and will have genuine concern about your investment. Find out how long any guarantees last.