Understand how material and technology dictate your mechanical results
When you develop prototypes or functional parts, the success of your project depends on how precisely the 3D printer can reproduce your digital dimensions. Precision is not a static number, but a result of your 3D actions and the chosen production method. Whether you are working at our facility or managing your own production, understanding tolerances is the key to a professional result. A 3D print that does not fit its intended counterpart is not only a technical failure but also a waste of 3D print time and resources.
The difference between precision in FDM and SLA technology
The technology you choose has a direct impact on the precision you can achieve. FDM (Fused Deposition Modeling) works by melting plastic through a nozzle. Because the plastic expands slightly when it leaves the nozzle and contracts when it cools, you should expect a tolerance of +/- 0.1% to 0.2%. For a part of 100 mm, this means a variation of up to 0.2 mm.
SLA (Stereolithography), on the other hand, uses a laser to cure liquid resin. This process is far more precise because there is no thermal expansion in the same way. Here, we can achieve tolerances down to 0.05 mm. While SLA offers higher precision, the 3D print price is often higher due to the material costs and the required post-processing. You should choose FDM for robust functional parts and SLA for high-detail prototypes and dental applications.
How shrinkage and cooling affect your 3D print price
All thermoplastics shrink when they transition from a melted state to room temperature. This is a physical law that affects your 3D print. Materials like ABS shrink more than PLA, which can lead to warping if the cooling is not controlled. If your part warps, the tolerances are lost, and you must restart the 3D print time.
At our headquarters, we use climate-controlled cabinets to minimise this risk. By choosing materials with low shrinkage, such as PETG or ASA, you ensure a more stable process. This reduces the number of failed prints and ensures you a better 3D print price because we can deliver a perfect result the first time.
Design for tolerances: The secret to perfect assemblies
If you are designing two parts that must fit together, such as a lid for a box, you should never design them with the exact same dimensions. You must build a “clearance” into your 3D model.
A good rule of thumb for FDM is to leave a gap of 0.15 mm to 0.3 mm between moving parts. If you want a “press-fit” where the parts stay together by friction, 0.05 mm to 0.1 mm is often sufficient. By including these tolerances in your CAD file before upload, you avoid manual sanding and post-processing, which directly lowers your total 3D print price.
