November 27, 2014 AT 12:30 am

Adding screw threads to 3D-printed parts #3DThursday #3DPrinting

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Here are some suggestions for how to incorporate threads into SLA/DLP 3D printed parts for metal fasteners from FormLabs:

…There are many ways to attach multiple 3D printed parts together, but if you need to repeatedly attach and detach components and want robust mechanical fastening, there’s no real replacement for genuine metal threads. All the same, we’ve come up with a few good ways to incorporate threads into your 3D-printed parts.

Here are some of the various design options (from most effective to least effective):

1. Print pocket for metal threads (i.e. add a nut).

Adding a hexagonal pocket to the backside of a face to pressfit a nut creates reusable, robust metal-on-metal contact. For extra twist-out strength you can choose a square nut. This nut can also be plastic or include locking features. If needed, a drop of CA glue will hold it in place, but modeling in a pocket from the side is even better as it eliminates the need for glue altogether. Use a 0.1 mm offset around the nut for a press fit and use a clearance hole around the screw itself.

2. Print threads and chase with a tap.

After printing the threads, leaving the part to post-cure in the sun for a day or two makes the part harder and easier to cut threads. These threads will still be relatively delicate depending on the size and are not the best choice for a permanent reusable fastening system. If you don’t have a tap (perhaps that’s why you’re printing the threads), you can just use a screw or nut to clean up the threads.

3. Use thread-cutting screws designed for plastics.

Follow the manufacturer’s guidelines for boss dimensions. This option is best-suited to prototype parts which will eventually be injection molded for these screws. The screws hold firmly but there is a risk of cracking the boss and the threads won’t hold up to repeated use the way metal threads will.

AVOID using press-fit or heat set threaded inserts! Even if they are designed for “plastic,” they do not work well in our acrylate photopolymer resins….

Read more about printed threading and fasteners at Formlabs!

Pasted Image 11 27 14 12 05 AM

Pasted Image 11 27 14 12 05 AM

Every Thursday is #3dthursday here at Adafruit! The DIY 3D printing community has passion and dedication for making solid objects from digital models. Recently, we have noticed electronics projects integrated with 3D printed enclosures, brackets, and sculptures, so each Thursday we celebrate and highlight these bold pioneers!

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