Guides6 min read13 October 2026 Bryan Kor

Our Free File Check: What We Look At Before You Print

Every file gets a free human check before printing. What we look at, how to flag critical dimensions, the tweaks we suggest and how to send revisions.

Every file sent to us gets checked by a person before it goes on a printer. It's free, and it happens before your part goes on a printer. We look at your model the way a printer will, spot the things likely to go wrong, and suggest fixes while they're still cheap to make.

Think of it as a second pair of eyes, not a gate. You know what the part has to do. We know how FDM behaves. Put the two together and the first print has a much better chance of being the last one.

What the file check is (and isn't)

The check is a review of your file for printability and fit. We tell you what we'd change and why. You make the changes in your own CAD, or decide to go ahead as it is.

The file check does	The file check doesn't
Flag thin walls, tight fits and risky overhangs	Redraw or remodel your part
Suggest wall thickness, clearances and orientation	Design a part from a sketch or photo
Recommend a material for the heat, sun or load	Certify a part for a regulated or safety-critical use
Point out where supports will go and what they'll leave	Cost anything

We're a print-only service, so we don't offer CAD modelling. If you need a model made, free tools like Tinkercad, Fusion 360 and Onshape are good places to start.

What we look at

Wall thickness. 0.8 mm is the minimum and fragile. 1.2 mm suits most parts. 1.6 to 2.0 mm for functional parts. Anything under 0.4 mm won't print.
Tolerances and holes. Typical tolerances are ±0.2 to 0.5 mm, and holes usually come out 0.1 to 0.2 mm smaller than designed.
Clearances. Parts that slide, snap or press together need a gap designed in.
Orientation. Layers are the weakest direction, so we orient load-bearing features so layers aren't pulled apart. Orientation also changes the finish and the price.
Supports. Overhangs steeper than about 45 degrees generally need support, which adds material and leaves marks.
Threads. Printed threads work best at M6 and up. Smaller, and we'll suggest heat-set inserts or self-tapping screws.
Scale. A model exported in inches arrives 25.4 times too small. It's an easy fix if caught early.
Size. The build volume is about 325 × 320 × 325 mm. Bigger parts can be split into sections that bolt or glue together.
Material. Whether your choice will survive where the part is going.

How to tell us your critical dimensions

The most useful thing you can give us is a short note on which dimensions really matter. Most of a part can be ±0.5 mm and nobody will notice. One hole or one slot usually can't. Tell us which ones, and we can dial them in.

Send it on Telegram or by email when you order. A good note covers:

Which feature. "The 8 mm hole on the left tab", or a screenshot with it circled.
The target size. The size it should be, not just the size in the model.
What it mates with. A bearing, a bolt, a 3 mm steel rod, another printed part.
The fit you want. Tight press fit, sliding fit, or loose enough to drop in.
Which way it can go. Would a slightly loose fit be fine, or slightly tight?
Where it will live. Indoors, outdoors, in a car, near heat, under load.

A quick photo of the thing it has to fit is often worth more than a page of measurements.

Typical tweaks we suggest

These are the changes we suggest most often. They're usually a few minutes in CAD.

What we see	Why it's a problem	Typical tweak
A 0.6 mm wall on a clip	Will print but snaps easily	Thicken to 1.2 mm, or 1.6 mm if it flexes
A peg modelled the same size as its hole	Holes print small, so it won't go in	Add clearance to the hole, or tell us it's critical
An M3 thread modelled in	Too fine to print cleanly	Model a hole for a heat-set insert or self-tapping screw
A flat roof spanning a box	Needs support inside that's hard to remove	Add a chamfer, split the part, or reorient
A long bracket loaded across its layers	Layers can peel apart under load	Print it on its side so load runs along the layers
PLA for a part in a car	Softens around 55 to 60 °C	Switch to PETG or ASA
A part a little over the build volume	Won't fit in one piece	Split into sections with a joint

For more on strength and orientation, see how strong are 3D-printed parts.

How to send a revised file

Revisions are quick. Upload the new file on the quote page and you'll get a fresh price in seconds.

Name your versions. bracket_v2.stl, not bracket_final_final.stl. It makes it clear which file to print.
Say what changed. "Hole enlarged by 0.3 mm, wall thickened to 1.6 mm" lets us check the right things.
Send STEP or 3MF if you can. We accept STL, 3MF, OBJ, STEP and IGES up to 100 MB, plus ZIP files for multi-part projects. STEP files don't need converting.
Sign in to keep your files. Signed-in users have a file library, so earlier versions are easy to find again.

Our guide to preparing STL files covers exporting and fixing common mesh problems.

After printing: photos and dimension checks

If a dimension really matters, ask for a check before pickup or shipping. On request, we'll send photos of the finished part and measure the dimensions you flagged, so you know before it leaves us.

And if a print does come out wrong or defective, report it from your order page within 30 days and we reprint it free. The details are on our returns page.

Quick FAQ

Does the file check cost anything?

No. It's part of every order and happens before your part goes on a printer.

Will you fix my file for me?

We suggest the fix and you make it. We don't offer CAD modelling, which keeps our prices tied to printing.

What if I want to print it as it is?

That's your call. Most flags are risks, not dead ends. Just know the free reprint covers prints that are wrong, not parts that printed exactly as modelled but don't fit.