Need to join two pieces together in your 3D print project? Don’t want to use screws and funky heat inserts? Here are some common screwless joints that I have collected all over the Internet that you can use in your project.
1) PIN & CAVITY
Complexity : Simple
Strength : Medium
One of the simplest joints. Pin on one side, cavity hole on the other. Very easy to apply and print, but there’s just one problem – You will need to get tolerance just right. Make sure that pin fits into the cavity super tight. There’s always the option to add glue too.
2) DOWEL JOINT
Complexity : Simple
Strength : Medium to strong
An “alternative” to pin and cavity, print the dowel (pin) separately. This opens up the possibility to print the dowel using a tougher material and even add more infill to strenghten the joint.
3) LEGO BRICKS
Complexity : Medium
Strength : Weak
An unconventional joint, but Lego brick is an interesting alternative for parts that are reconfigurable. There are plenty of free STLs and parametric generators all over the Internet for you to use, even commercially – The patent for Lego bricks have expired. Just don’t use the word “Lego” in your project, it’s a registered trademark.
Take note though, Lego bricks require pretty accurate tolerance. If you adopt these, using 0.6 or larger nozzles for your project are out of the equation.
4) FINGER JOINT
Complexity : Simple
Strength : Medium
A woodworking joint. But personally, I am not a fan of this joint. It’s usable, but I prefer Dovetail joints that are technically stronger.
5) DOVETAIL JOINT
Complexity : Simple
Strength : Medium to strong
Another common woodworking joint. This is one of my favorite joints, easy to apply and strong.
6) SLOT IN COVER
Complexity : High
Strength : Weak
I don’t think this needs much explanation, you have probably seen this everywhere – Remote controls, battery cover, boxes. This is not a permanent joint, used for parts that needs to “open and close” rather frequently.
7) CANTILEVER SNAP FIT
Complexity : High
Strength : Weak to medium
A common “clip and hold” semi-permanent joint. While this is a common Joe, it comes with a caveat as a 3D print. Some people may think that laying the clip piece flat is a better idea – Print without supports. But think again, the clip will break easily because the layer lines.
8) U-SHAPED CANTILEVER SNAP FIT
Complexity : High
Strength : Weak
Yet another common Joe, you should have seen this in battery covers. I think this holds a little better than slot-in, but it does require quite a bit of space – Not for small and tight builds.
9) ANNULAR SNAP FIT
Complexity : Simple
Strength : Weak
Pretty much a “cover with notch”, commonly used in pens and round containers. Not a permanent joint, the snap fit does wear out over time.
10) TORSION SNAP FIT
Complexity : High
Strength : Weak to medium
Technical folks should be very familiar with this one. Cable clips. This is not a strong permanent joint, just a mechanism to better hold two separate pieces together.
11) STUD & SOCKET
Complexity : High
Strength : Medium to strong
I call this the “upgraded” version of pin and cavity. It does hold things better using tension, not easy to release too. Can be made beefy and holds things pretty well.
12) TWIST LOCK
Complexity : Medium
Strength : Weak
Not a permanent joint. Commonly used in bottle caps, container covers. Convenient twist-on-off design, just not very strong.
13) BALL JOINT
Complexity : High
Strength : Weak
Folks who dabble with Gunpla should know this one, a flexible joint. This is not strong by any means, wear and tear happens over time too.
14) VELCRO
Complexity : Medium
Strength : Weak to medium.
Yes, we can print velcros with 3D printers. Don’t be mistaken – A large beefy piece can actually hold quite a bit of weight.
15) MAGNET
Complexity : Simple
Strength : Weak to strong (depends on magnet size and grade)
Lastly, a rather common solution in the 3D printing world – Attach a piece of magnet to your project. A small piece of magnet is good for general use, a fridge magnet can hold knives, an industrial magnet can hold elephants.
STL DOWNLOAD & TINKERCAD
That’s all for this quick list of common joints, enjoy and happy printing! You can download all the STL files on Printables, or edit them on Tinkercad.