Practical Tips for Manufacturing Large 3D Prints Reliably

Large parts often require special attention to orientation, cooling and joining, and can be quite tricky to work with. There is a way of handling large prints at our 3D printing service to ensure that those prints will reach our clients safely and will function as planned.

Upside Parts - Large 3D Prints

Below we have decided to share with you some tips on how our 3D printing engineering team approaches large 3D prints when the model is bigger than the build volume.

What We Check Before We Start Manufacturing Large 3D Prints

1. Split

First of all, we need to make sure that splitting is permitted, and we can manufacture a part consisting of several pieces that will be further joined together.

2. Accuracy and tolerance

In addition, we need to understand if the part we are required to produce is a technical one with strict tolerances, or a visual prototype where the way it looks matters more than its exact dimensions. For parts with tight tolerances we may need more iterations for test prints.

3. Material

We would also need to know if the material is fixed, or we may offer some alternatives. Some materials may have a higher level of warping or may be less suitable for bonding after printing.

4. Post-processing

The next thing we need to decide is if it is allowed to post-process the part after printing, using sanding, filler and/or paint. Without finishing seams may remain visible and it may significantly impact the impression of the result.

5. Strength

Finally, we need to learn about strength requirements for the part. If any load is to be carried, it’s necessary to plan seams according to this expectation.

When We Do Not Recommend Split 3D Printing

There are some cases when we think that 3D printing might not be the best way to produce large objects and other manufacturing technologies should work better. In particular, we recommend avoiding 3D printing when finishing is not allowed and as such seams cannot be hidden, as well as when the seam must carry high loads or when accuracy of large 3D prints is a strict requirement.

How to 3D print large objects with splitting and assembly

• Split geometry and seam placement

Most of the time we use two cut styles: (1) a straight cut, and (2) a dovetail cut.

We tend to use a straight cut if there is a wide, flat area. A bigger bonding area usually reduces joint stress and makes alignment easier.

A dovetail cut may be quite helpful when we need mechanical interlock in one main direction. At the same time, we avoid using it when the main load would peel the seam.

• Match orientations for matching parts

If two sections have similar geometry, we print them in the same orientation. Orientation affects shrink and distortion, so matching it reduces mismatch at the seam.

• Allowance for adhesive

Adhesive needs space to wet and fill the interface. We remove a small amount of material at the split interface so the glue line does not push the final assembly out of tolerance.

Why 3D Printing Technology Choice Matters

SLS 3D printing is often chosen for mechanical parts and is commonly described as having more uniform properties across axes than typical FDM prints.

But nylon is challenging to bond because of low surface energy and moisture related effects, so seams can become the weak point.

Resin 3D printing can deliver fine detail, but properties depend on post-curing.Using the same resin as an adhesive and curing it with UV is common for cosmetic assemblies, but bond strength varies and should be validated.

For large 3D prints that can be finished, FDM 3D printing is often the most economical option. ABS is frequently selected for multi-part builds because it can be solvent welded, where the solvent softens the polymer and chains interpenetrate as it evaporates. If you are deciding between ABS and ASA for a large part, see our guide Comparing ASA vs ABS 3D Printing for Practical Use.

Please take into account that some solvents used for plastics bonding have significant health risks, so correct safety controls matter.

Two Cases from Our Day-to-Day Work

Large Part for an Autonomous Vehicle

We had a project for a large part used on an autonomous vehicle. It could not be printed as one piece, so we needed to split it and assemble it. The customer was fine with that. They also did not need micron-level precision. The main requirement was to land the overall size within a range, about plus or minus one centimeter on a key diameter.

Even with that relatively forgiving target, we did not hit the size on the first build. We printed the sections, assembled them, checked the diameter on the finished assembly, and then adjusted the scale and printed again. We repeated that loop until the final size landed in range.

The point is not that something “went wrong”. When you split a large part and then bond it, you only learn the real geometry after assembly. If the overall size matters, you should assume you may need more than one build, and plan time for that.

Large Art Object for an Exhibition

We also produced a large art object on a tight budget that ended up in a museum exhibition. This one worked well with splitting because finishing was allowed. We could sand, use filler where needed, prime, and paint.

The shape mattered, too. It had smooth curves rather than strict geometry like a perfect cube. With curved surfaces, small dimensional shifts are harder to notice. That gave us more room to choose a cut plan that made printing easier.

We split the object on purpose. With FDM, printing a large curved shape as one piece often forces lots of supports and leaves marks that take time to clean up. By splitting it into sections, we could orient parts in a way that reduced supports and gave cleaner surfaces.

We did spend time bonding and blending the seams. But we avoided fighting surface defects across the whole object.

Sometimes, a one piece print sounds best, but on large curved shapes in FDM it can create more supports and more visible marks. Splitting lets us choose better orientations for each section, then we hide the seams during finishing.

Practical Considerations

If you are deciding how to 3D print large objects, we recommend first identifying things that matter most for your particular project, including tolerance, material, finish, and process. Then design the split and join plan around load paths and visible surfaces.

We support 3D printing Boston projects as well as ship parts to our clients across the US. If you would like to discuss how to 3D print large objects on a tight schedule, please share the timeline upfront so we could assist you within the established deadline. Based on your 3D model, tolerance and finish requirements, we will propose a cut plan and flag risks early.