MYP Design File Formats and Version Control Notes

A File Format Is A Promise About What Survives

1. Every time you export, some of the information in your model is kept and the rest is thrown away for good.
2. An STL keeps the outer shape and nothing else, so the feature tree, the dimensions and the materials all vanish.
3. A STEP file keeps true curved surfaces and separate solid bodies, which is why another CAD package can open it and still measure it properly.
4. Your native file, such as an .f3d from Fusion 360 or an .sldprt from SolidWorks, keeps everything but only opens in that software.
5. Keep the native file as your master and treat every export as a one way copy you can always make again.
   1. Editing an STL back into a proper model is slow and ugly, so never let the export become the only copy you have.

Matching The Format To The Machine

1. DXF is a 2D vector format that laser cutters and CNC routers understand, and it holds real millimetre sizes.
2. SVG is also 2D vector, used on the web and by many smaller cutters, and it opens in free software such as Inkscape.
3. STL describes a 3D surface as thousands of tiny triangles, which is all a 3D printer slicer needs.
4. STEP is the format for handing a 3D model to someone using different software without losing accuracy.
5. PDF is for anything a human reads, such as a dimensioned drawing or your whole design folder, because it looks the same on every device.

Exporting Is Where Good Models Break

1. Check the units on the export dialogue, because a model exported in inches arrives at the printer 25.4 times too big.
2. STL resolution matters, since a coarse setting turns a smooth cylinder into a visible hexagon in the finished print.
3. A fine STL setting can push a simple part past 50 MB with no visible improvement, so use medium unless the curves are shallow.
4. For DXF, export the flat face or sketch rather than the 3D body, or you get a tangle of edges the cutter cannot read.
5. Reopen every export before you rely on it, because a two second check catches a file that exported empty.

Name Files So Future You Can Read Them

1. A good file name says what it is, which version it is and when it was made, with no guessing required.
2. Something like deskTidy_base_v04_2026-03-11.f3d sorts correctly and tells you everything before you open it.
3. Write dates as year, month, day, so the computer sorts them into the right order on its own.
4. Number versions with a leading zero, because v10 sorts before v2 otherwise.
5. Avoid spaces, slashes and full stops in names, since some machine software silently refuses to load them.
6. Names like final, final2 and FINALreallyfinal are how people lose a week of work.

Save Versions As You Go, Not At The End

1. Save a new version number whenever you make a change you might want to undo later, such as before reshaping a handle.
2. Cloud CAD such as Onshape and Fusion 360 keeps its own version history, so add a short comment each time you save.
3. A comment like widened base to 90 mm after it tipped over is worth more than the version number by itself.
4. Version history means a mistake costs you one step back rather than a full rebuild.
5. Never overwrite a version that has already been cut or printed, because you may need to remake that exact part.

Two Copies In Two Places, Or You Have No Backup

1. A file that exists in one place only is one dead laptop away from gone.
2. Keep the working copy on your computer and a synced copy in your school cloud storage, such as OneDrive or Google Drive.
3. Sync is not the same as backup, because deleting a file on the laptop deletes it in the cloud within seconds.
4. Export a dated PDF of your design folder at the end of every fortnight and keep those PDFs untouched.
5. Back up your photographs too, since a photo of a failed prototype cannot be retaken once the prototype is in the bin.

File History Is Evidence Of Development

1. A row of versions from v01 to v09 shows a real design process in a way that one polished final model never can.
2. Screenshot v02, v05 and v09 side by side with a line under each saying what changed and why.
3. Include the versions that failed, since abandoning an idea for a stated reason is design thinking, not wasted time.
4. A screenshot of the cloud version list with your comments visible is quick evidence that the development was yours.

Handing Files To Someone Else

1. Send a STEP file if the other person needs to change the model, and an STL only if they are printing it as it stands.
2. Include a PDF drawing with key dimensions so nobody has to guess what matters.
3. Say which units the file is in, even when it should be obvious, because that one line prevents most scaling disasters.
4. Zip a folder of related files together rather than sending eight separate attachments.