Re: Tapping into 3D Printed Parts
 

THIS. Probably my favorite way to fake threads in a 3D printed part.
Helicoils (as Arthur mentioned above) are also good. I prefer to use the standard threaded inserts from McMaster usually though: http://www.mcmaster.com/#standard-th...serts/=10vencg
They do not require the special helicoil insert tool.

Re: Tapping into 3D Printed Parts
 

A T nut seems like it was invented for this. Just print the hole the diameter of the T Nut and you're golden

Re: Tapping into 3D Printed Parts
 

Yes, this is by far the most effective means of including threads on printed parts.

Re: Tapping into 3D Printed Parts
 

IMO, the best way (without a helicoil or nut insert) to have an axial loaded internally threaded screw hole in 3D printed parts is to just have an undersized pilot hole and use a coarse thread deep V-groove (not machine thread ) screw that can cut its own thread on 1st installation. Some plastic compatible lube my help avoid tearing up the material as screw forms the thread.

This should also allow for best results when multiple cycles of assembly and disassembly will be needed.


Deck screws come to mind, with a well tapered point. Their coarse thread will give deeper engagement with the plastic and put the plastic adjacent to the hole into tension as the screw enlarges the initially undersized pilot hole as it forms the threat rather than cuts material away.

-Dick Ledford

Re: Tapping into 3D Printed Parts
 

This really depends on your application. We 3D printed the shooter release mechanism on our 2014 practice robot so we wouldn't have to machine two. We printed 'threads' (they really didn't turn out well) and forced a nylock nut on the back of it and it lasted all season.

However it's important to note the part was being loaded in shear and not in tension. I would not recommend loading a 3D printed / plastic thread in tension for an application that applies a load of more than a few pounds. Conversely, I don't see any problem with using this method to load fasteners in shear. I've done this before for personal 3D printed projects and didn't even bother tapping the hole, I just drilled out the hole with the tap drill and drove the bolt in. YMMV.

Re: Tapping into 3D Printed Parts
 

In the past I have printed a slightly undersized hole then drilled it to a tight tap diameter, then used machine screws to force threads into it. Alternatively,you can design a part with a hexagonal cavity, pause the print and insert a nut, then allow the printer to seal it inside. Both options have been successful to me when building H class rockets subject to large ejection charges. I print the nosecones and electronics bays and fasten eyebolts to tie the parachute onto these parts. Everything gets blown out of the top of the rocket body and then arrested by a shock cord. Never had an issue with threads pulling loose

Re: Tapping into 3D Printed Parts
 

Someone on my team did that, except he also pointed a heat gun at the 3D printed part before he forced the screw on to soften it around the screw. It worked, but then again he was just making a mount for a computer fan and so didn't need much strength.

Re: Tapping into 3D Printed Parts
 

bit of a correction: I heated up the bolt only, and with a hot bolt, threaded the plastic. Pointing a heat-gun at the piece would have probably killed it :p

The threads are clean, and I would think that this is the strongest way to tap a piece of plastic, but that's just my gut feeling.

Of course, it also depends on how deep the threading is, and the bolt size. But like others have recommended, putting a nut on the other end would make a undoubtedly stronger product then my method.

Re: Tapping into 3D Printed Parts
 

It's been mentioned a few times already but I'll reiterate that heat-set inserts are the way to go.
This is what we use:
http://www.mcmaster.com/#heat-inserts/=10w65lb

We've used self tapping inserts for plastic as well, however, a printing lab at JSC recently did a pull out study testing different inserts in different 3D plastics and they found the heat-sets performed best.

They're inexpensive and easy to install with a soldering iron. Just file away any melted plastic that raises above the surface.

Re: Tapping into 3D Printed Parts
 

While there's a lot of fantastic advice on here about how to do this right, in a pinch and when the forces are in the right directions, you can get away with threading directly into a piece of plastic. As an example, we used 100% fill ABS printed pieces as clevises (clevii?) on the 'Snow Problem catapult. Here's an imgur album with pictures of the implementation. Personally, I wouldn't recommend it, and I'm somewhat surprised they've held up for the couple hundred shots we've taken with Perses, but in this particular use case, it worked out to thread directly into the plastic.

Re: Tapping into 3D Printed Parts
 

Last year my team created belt tensioners that were adjusted by turning a bolt that was threaded into the part. We used ¼-20 for this. Our printer is a Stratasys SE Plus. We printed test parts in 3 different settings of sparse, high density sparse and then high density. (Basically increased the infill %, but the software doesn't allow for direct control of that). We found that the latter two, when threaded with ¼-20 and put into a clamp below the threads, were able to lift and hold up one side of a "lab table". By lab table I mean one of those tables with a slate top. it was remarkably strong. These prints are at .13mm layers or less though so be careful when using a non-industrial quality printer. Best of luck!

Re: Tapping into 3D Printed Parts
 

I actually do this a lot at work for lower load applications. Most bolts can self tap the hole in the plastic if you print the correct size hole and use a higher shell count. (Even the end of a pneumatic) Speaking from experience, if you are going with ABS, PLA, or PET, I would recommend a higher infill than 5% as in one of our experiments it wasn't the hole or threads that failed but the infill. I haven't done extensive testing but using that sort of force you are probably looking at >=25% infill around the threads and a few layers below the bottom of the hole (if the threads don't pass all the way through the part) and the parts would still be considered consumable. (My work printer is .2mm layer height)

Re: Tapping into 3D Printed Parts
 

What I have always done is print the hole slightly undersized the for the bolt then I force the threads in with the bolt. Works well for non-load bearing part if printed with PTE. Not sure about PLA or ABS.