Yes, hollowing your resin 3D prints can be a good idea, especially for large or complex models, as it saves on resin, reduces weight, and can help prevent print failures. However, it also introduces some potential drawbacks, such as the need for drain holes and potential for leaks.
Reasons to Hollow:
- Resin Savings: Hollowing significantly reduces the amount of resin required for a print, saving money and resources.
- Reduced Weight: Hollowed prints are lighter, which can decrease the chance of print failures, especially with larger models. Effectively, you can use “light supports” with smaller contact points since the pulldown weight is not heavy.
- Fewer Supports: Hollow prints often require fewer supports, leading to less cleanup after printing.
- Reduced Stress on Printer: Lighter prints put less stress on the printer’s build plate and lesser pull force on the FEP film.
- Easier Printing for Large Models: Hollow prints can make large, complex models easier to print by reducing the overall weight and stress on the printer.
Potential Drawbacks:
- Leaking Resin: Uncured resin can leak from drain holes or through the walls of the hollowed print. Of course this is easily solved by throughly flushing and washing the models. Use a spray bottle to squirt in the holes or let it sink into the IPA or water and make sure you see it bubbling down as the air escapes.
- Need for Drain Holes: Drain holes are essential for allowing uncured resin to escape, but they can also weaken the print.
- Curing Challenges: Ensuring complete curing inside the hollowed print can be tricky. You will need a UV torch to shine in through the holes to do this effectively.
- Structural Integrity: Hollow prints may be more fragile than solid prints, especially if the wall thickness is too thin. There are no recommended settings and keeping the walls thick is not really the answer. It depends on the model.
When to Consider Hollowing: I Bold This Section. IMPORTANT!
- Large Prints: Large models often benefit from being hollowed to reduce resin consumption and potential print failures.
- Check the hollowed model thoroughly. Make sure there arent any isolated chambers which could trap the resin inside.
- Wall settings shouldn’t be too thin. If you generate infill supports, internal supports may show and warp the model from the inside.
- Wall settings shouldn’t be too thick. You will risk creating unwanted chambers as the thick walls closed in together at certain areas.
- Non-Functional Parts: If you’re printing a model that doesn’t need to be structurally strong (like a figurine), hollowing is a good option.
Consider the example below. Creating thick walls may close up and isolate Eeyore’s ears. Too thin and the ears become too flimsy. This problem presents itself at the tail section as well.
Drain hole is situated at the bottom of the belly as it will be hidden. However, uncured resin at the leg section might not drain out properly during the wash. Furthermore, it is at an angle where it might not cure in the Curing Station.
Curing Considerations:
- Cure with Care: Use a UV curing station or sunlight to ensure complete curing of the resin, both inside and outside the hollowed print.
- Avoid Over-Curing: Over-curing can cause the resin to shrink and potentially crack the print.
Our Conclusion:
Most STL designers will have an hollowed option in thier STL design, especially those who design large models and terrain. These are usually test printed and left to sit for a few months to confirm that the hollowing is a success.
So its very unlikely that you will need to hollow out models. Also, wargaming miniatures are often too small to be given the hollow treatment.
In the event that you really needed to hollow a model before printing, checked that your slicer comes with a Cavity detection function. This will check for any isolated chambers which do not have a direct access to a drain hole.
