How to Prepare Your File for 3D Printing: A Pre-Send Checklist
Before sending an STL for printing, check six points that decide whether the part succeeds: units, walls, watertight geometry, orientation, and clearances. A practical guide that saves you time and money.
A ready file saves you at least a full day; a file with problems either comes back with questions or produces a part that is not what you pictured. The good news is that most problems repeat and are caught by a quick check before sending. Here is the checklist we wish every customer ran through.
1. Units: millimeters, not inches
The most common mistake and the easiest to catch. The 3D printing world works in millimeters, and some design tools export in inches or centimeters by default. The result is a part 25 times too small or ten times too large.
The quick check: open the file in any viewer and read the dimensions. If your phone stand reads 6 by 3 by 8, you exported in centimeters. Write the target dimensions in millimeters in your message even if the file is correct; it removes all doubt.
2. Fully closed geometry
The printer needs to know what is inside the part and what is outside, and that requires a closed surface with no holes in the mesh. Carefully modeled files are usually closed, but models converted from a scan or assembled from several pieces often have gaps or flipped surfaces.
Do not worry too much about this one: mesh repair is part of our job and we do it free in most cases. What matters is telling us if the model came from a scan so we can expect the issue.
3. Wall thickness
Any wall thinner than roughly half a millimeter will not print reliably and may vanish entirely. That includes thin edges, fine engraved text, and hair-like ornamentation.
The practical rule: keep the thinnest part of your design at no less than one millimeter if it is cosmetic, and two millimeters if it takes any load. Raised text reads better than engraved text, and each letter should stand at least half a millimeter proud to be legible.
4. Clearance in assembled parts
If your design is two parts that fit together, or a lid on a base, do not model both at identical dimensions. Printing has a layer thickness and finite accuracy, and identical parts will not assemble.
Leave a gap of 0.2 to 0.4 millimeters between mating surfaces: 0.2 for a tight press fit, 0.4 for free movement. If you are unsure, tell us the kind of fit you need and we will set the clearance during preparation.
5. Holes and threads
A printed hole comes out slightly smaller than its modeled size, especially horizontal holes. If your part has a hole for a 4 millimeter screw, model it at 4.2 or tell us the real screw diameter.
Printed threads work on relatively large parts; for very fine threads it is better to leave a pocket for a metal insert pressed into the part, which gives far more strength.
6. Orientation and where the weakness sits
A printed part is strong within a layer and weaker between layers. So if your design has a thin arm that will be bent, print orientation decides whether it snaps or holds.
You do not need to work this out yourself: tell us how the part will be used and where it will take force, and we choose the optimal orientation during preparation. That information is worth more than any technical setting you could send us.
What do we fix for free?
Mesh and hole repair, unit correction, orientation choice, support setup, and small clearance adjustments are all part of preparation and are not charged. Rebuilding a completely broken model, converting a sketch into a model, or changing the design substantially is modeling work, starting at SAR 100.
Ready to send? Attach your file on WhatsApp with the target size in millimeters, the quantity, and the intended use, and we will reply with a quote and lead time the same day. And if you are unsure about any point on this list, send the file and let us check it for you.
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