Threaded Inserts in 3D Prints - How strong are they? 

Matthew Humphrey exactly, plastic threads are sensitive to torque as he said and wear out quickly even with the right torque tightening

@@rotorblade9508 Not if you use a proper screw with threads designed for plastic. I don't get why people use machine bolts in 3d-printed objects as they are designed for metal threads. There exists such a thing as screw designed for plastic. You can get these for free from any broken appliance with plastic enclosure. Easier to use, better grip, and no need for threads, just a suitably sized hole.

@@ilkkavierula6664 The screws designed for plastic work great in applications where you screw it together and then never take it apart. Since these screws are designed to cut threads, if you remove them and put them back in, it's very easy to accidentally cut a new set of threads instead of screwing into the existing threads. That is a recipe for stripped threads. On commercial products, you often see thread-cutting screws holding most things together, but then a threaded insert and machine screw on things like battery doors that get repeated use. If you are able, you should have both thread-cutting and machine screws on hand and use the best screw for any given job. If your screw variety is limited by space, budget, or other factors however, I would consider machine screws to be more versatile.

​@@jcon6734 Most of the time they settle on the existing threads. Especially if you start screwing with light force without forcing it (as you are supposed to do with any screw). Even if the screw cuts multiple threads it doesn't significantly weaken the holding power of the screw. This is due to the mechanics of how to screw works. The factor determining the holding power of screw in material is the shear strength of the material and screw threads. The variable determining the shear strength is the shear surface area and shear strength of the material. The amount of material removed by the thin thread of a plastic screw is so little it hardly has an effect on the shear surface area, thus the effect on pullout strength is very small. It can be a bit counterintuitive, but you can try it yourself by screwing a piece of wood to a phone catalog or old book. It will hold there very firmly even though there are hudreds of "threads " between pages. To pull out the threads would have to punch through hundreds of sheets of paper, which anyone who has tried to hole punch through a thick stack of paper knows takes a lot of force. Most of the times when screws fail in plastic it's caused by poor tolerances of screws and holes. If the hole is too big for the screw's cylindrical body, the screw can move sideways under cyclic loads, slowly chipping away the plastic holding the screw. Overtightening and sideways loads during tightening will also cause this. If a screw needs to withstand huge amount assembly/disassembly cycles (more than a few dozen) best option is a self-tapping threaded insert. These are stronger than mold-in ones (especially when used incorrectly as melt-in with) or helical coil inserts (which are not intended for this purpose at all, they are for thread repair). Mold-in inserts will not bond properly when installed using melt-in technique with soldering iron or similar. They require either ultrasonic welding device, or proper heat press if they are not injection molded in place. Hole tolerance is also critical for them to work. Edit: If you want to study more, may I recommend: www.stanleyengineeredfastening.com/-/media/web/sef/resources/docs/other/threaded_fasteners_for_plastics.ashx techcenter.lanxess.com/scp/americas/en/docguard/Joining_Guide.pdf?docId=77016 www.celofasteners.cn/img/cms/Cat%C3%A1logos%20industria/Screws%20for%20plastic%20CELO.pdf www.spirol.com/library/main_catalogs/SPIROL-Inserts-for-Plastics-us.pdf As some good starting points.

@@ilkkavierula6664 It seems like you know your stuff. Since the screws aren't actually removing material, it makes sense that cutting a new set of threads wouldn't weaken it too much. That said, it sure seems like I constantly strip threads out when I'm not careful to catch the original threads. Any thoughts on the actual problem? Am I just particularly ham-fisted? I will say that I disagree with you on the heat-setting threaded inserts. While they might not bond "properly," if the plastic is breaking before that bond fails, I'd say it's good enough. The self-tapping inserts might technically be better, but they're also an order of magnitude more expensive and I'm not sure you'd see much real-world benefit.

I do too

Me too :) And i'd be interested if results with PETG are the same, cause that is the material i use 90% of the time ^^

Me too.

M3 is definitely the most used for 3d prints

Same. M2 for the tiny stuff and M3 Torx head for pretty much everything else. Usually don't print parts that require something as large as a M5.

Damn, now i feel bad. Somehow, even without being subscribed, youtube always answered my questions with the perfect CNC kitchen video.

I don't need to subscribe. youtube keeps recommending this channel anyway even though I don't have a 3D printer. 😁

cool, I'll have to try that

yeah square nuts are better i just had a hard time getting them and have 1000+ of normal hexagon nuts 😁

@@tetraliteproducts542 you can buy square nuts off aliexpress for 1/10th the price

Yea it's really simple to do nowadays, too. For additional strength an easier insertion I can only recommend getting some square nuts (as others already suggested), as that basically removes any chance they'll start turning inside their cavities. For the same reason you also gain some leeway since the fit doesn't have to be as precise. You can also insert them in a vertical orientation without needing 'filler' parts to plug the cavities at the top a hex nut leaves. Try getting the thin version, as they don't have a more 'rounded' side and are completely flat on both sides. In Germany those are the DIN 562 variant (the thicker ones are DIN 557).

It was a major pity that the torque wrench was out of a Kinder Egg!

The ratio of time needed to end up with an 11 minute video must be at least 100:1. Just to do the engineering and get the raw footage. Even more after editing. I'm certain there are very few Creators who have so much hard work behind each minute of video.

The machine deflects before the part yields. Not very accurate

@@sheet-son Well I don't expect him to buy a super expensive tensile testing machine. So given his tools and budget, it is pretty accurate.

@@dmail00 Actually, a beam type torque wrench can be very accurate for this kind of thing. Typically better and more repeatable then a click type or electronic.

square hole ?! thx I'm gonna try that in my next design

That is quite genius. Thanks for that tip.

How do you avoid getting hotend hitting the insert?

Yes, doubly so if the inserts are brass. Brass is too soft to give a strong joint with the normal pitch of metric threads. That is why he stripped out the threads when he tightened too far. #316 or $304 stainless inserts are better for strength but not as good for repeated use because they tend to gall.

@Roderick storey Self tapping is also a cheap option. Even if the cover needs to be removed once a month, so long as the self tappers work for about a year, they may be used in a cheap product.

Old video and comment, but I 100% agree, the "nut pocket" (as used significantly in the Prusa MK3S) is another great method and I think simpler overall.

Great test. But as Kartaurus is pointing out you should have drilled 4.2 mm. I have used 4.5 mm for M5, but only for selfthreading screws.

Sanladerer is influential.

It's easy.

yes, PETG, ABS, ASA and perhaps Nylon would be great. Threads are usually to be used in straonger (constructional) material so it would be great to know how to do threads for mentioned materials :)

Get the beta. It's a lot less bad.

It's not bad in the regular, non-prusa, version

My point was that Slic3r has the functionality, in contrast to what is said in this video. But the update is indeed a huge improvement. Though the old system was good enough to make a print succeed that would have failed without it.

I have to apologize for my fellow Americans. They are stuck in their ways, I wish we used metric.

only idiots would say it like that :P

I absolutely love the metric system.

as an American: metric is great for small things and precision. but you cant beat inches when it comes to rough construction like framing. it's easier/faster to say and cut 96 and a half inches rather than 2.4511 meters

CNC Kitchen Ich würde dir KEENSERTS Gewindeeinsätzen empfehlen. Die halten in Kunststoff Bombenfest. 😬😑

I would’ve subscribed if it wasn’t for the way you say Slic3r. :)

The annoying background music ruins the video???? why did you even bother adding music that 99% of people will not enjoy and about 20% will just stop watching?

Feel free to share the video (link or embedded RU-vid player) but please don't re-upload or self host it.

3d printed parts is made of plastic just melt the thing together to make connections

I used these: ebay.us/jRsctU

Yes, helicoil!

Yes!

Just commented pretty much the same. I also think that embossing normal hexagon nuts is one of the easiest and sturdiest things to do. I use it in pretty much all of my own designs if I need to screw something into plastic model. Most surface area/perimeter walls to support normal nut. Actually haven't specifically tested them, but they've never failed when I've used this modeling style.

Or Australians.

Are the ones you're talking about with big coarse external threads? I have used a version that's 1/4"-20 inside and 3/8-16 outside.

@@thewheelieguy I don't know the measurements of the thread, sorry. But they are wood inserts with a very coarse thread and I used the m4 and m5 variants so far.

Yes, 1/4" at 20 threads per inch. It may be archaic but it's a useful international standard.

We are manufactured brass insert components and mouldings components

Nice Head Unit you made out there. I just bought a DJI Spark drone and i look forward for your video. Subbed :)

@@theodornitu Thank you for the support! Hope you all have a great day!

The problem with M3 is that the head of the bolt and the nut are quite small and can't take any load. Using a washer and a brass insert will make them way better. I use M5 and M6 otherwise, it is not about the strength the bolt&nut can take but the area that the bold head and nut will cover to get just a bit more torque and to prevent creep.

@@squidcaps4308 I think, the brass inserts would really help m3, since you make the influence of the head size less

Considering many tripod camera bases are made from plastic, you'd probably be fine.

We are manufactured brass insert components and mouldings components

1:58

So Simplify3D is pronounced Simplified?

unless the nut was inserted from the underside with a small lip at the top surface, wont the nut just pull out the moment you try to tighten sth down?

@@JoshuaLotion I usually put the nut in on the other side, yes. In my experience it's rare that the design doesn't allow that. And with the right tolerances I have to pull the nut into the hole using a screw, which holds tight enough afterwards that I had to destroy some printed parts to get the nut out again. It's good enough for my purposes and I can get nuts in every hardware store.

@@SaHaRaSquad Yea that does sound pretty effective and considering i have a whole box of various sized nuts. this is probably gonna be a method im gonna start using. thanks for the tip

From some other videos, I have gathered that it is practical to increase the fill percentage near holes etc. I wish I could remember the name of the video but some guy was varying the fill to get stronger parts where needed. It seemed that he was making an object within an object to define the volume with the high fill rate. The rest of the part was very lightly filled except the skin.

Nylon sucks for such uses. It is not stiff enough. Nylon is tough so it is good for applications where giving a bit but not failing is the best option.

@@kensmith5694 you have a point.

@@stalawina Do you use threads or inserts? That is the topic

@@stalawina Inserts will do better. They spread the same force over more area. I suggest stainless ones for high loads. Brass avoids galling but is too soft for the standard metric tread sizes. Most folks don't want to have to use special screws. #304 stainless is almost hard enough to get the full rating out of standard screws.

I try to change the link in the description.

Interesting to know. Where is the difference?

The shape! The ones you liked have a shape that alows the to more easily slip out. Even the insertion is not as easy or more prone to be inserted crooked because they miss the taper at the start. I think the cheap ones are met to be injection molded. Anyway cuting a thread direcly in the part was better for me than using the cheap ones.

​@@Chaosstifter87 I agree with you 100%, the linked cheap Aliexpress brass inserts are useless for our purposes and are not designed for use as heat-set inserts in 3D printed parts.

I used those: www.ebay.de/itm/272628154302

The advantage is you don't need to use a soldering iron to put them in and you can easily remove them again.

Yes 😎

200% lol

Haha, you're not the first one thinking that.