The difference between STEP, STL and 3MF File Formats
Within 3D Printing and CAD, your design files can be saved and exported in many different formats. STEP, STL and 3MF being the three most common types – despite holding the same part/design – there are still many differences and advantages with each file type. In the additive manufacturing industry, part quality is everything and by maximising the quality whilst maintaining a low file size we are able to achieve the same high quality part. It may seem like a minor detail, but here at All 3D Labs we want to achieve the best with your printed parts. This starts with the file you send us.
What is a STEP file
A STEP file stands for Standard for the Exchange of Product Data, abbreviated as .stp. Because this is common for modelling and designing, many designs will originate in this format.
STEP files contain mathematical data to represent curves and finer detail, with exact precision and true shapes allowing for accurate design. For 3D Printing purposes, a STEP file would have to be converted to a triangulated format in order to be printed.
What is an STL file
An STL is a common conversion from a STEP file used for 3D printing. Known as Standard Triangle Language. Files saved or converted to this form contain surface level detail from connected triangles. The smaller the triangles, the more accurate the surface geometry that is maintained.
These finer triangles lead to a greater number of triangles per part, which can massively impact the file size. Ultimately, the file size reflects the level of detail and this will even be greater than the original STEP file. For a complex geometry, many triangles are needed to maintain an accurate surface representation, but this will create a large file size that can be quite difficult to share, store or manipulate.
Two STL files, converted from the original STEP file to create a triangulated part, however with their low file size you can see the geometry is not smooth enough. Above – 45kb. Below – 70kb.
What is a 3MF file
Looking lastly at 3MF files, which are becoming more common in the additive manufacturing world. Abbreviated from 3D Manufacturing Format, this file type was created to face the shortfalls of others available. Becoming the most versatile for sharing, printing and maintaining the same high degree of accuracy as the other forms. Similar to an STL file, a 3MF works off of triangular data, but creating a much smaller file size. A 3MF allows a higher number of triangles, leading to maximised surface accuracy whilst maintaining a much smaller file size, without any loss of triangles or detail.
The main difference between file formats for 3D Printing…
STEP – You’re sending us the original file, we’re controlling the quality
STL – You’re controlling the quality, but restricted by file size
3MF – You’re controlling the quality, without restriction from file size
It still surprises people that you can see visible triangles on printed parts. This is due to the high resolution of our HP Multi Jet Fusion printing process.
For any 3D printing, by sending us the original STEP file we can control the size of triangulation necessary to maintain the best surface geometry for your part. If you want any more information about our 3D printing services or how best to send us your part/design then feel free to Contact Us.
