Threaded Inserts for 3D Prints - Cheap VS Expensive 💰
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- Опубліковано 29 вер 2024
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I tested different types of threaded inserts for their strength and usability to find out if it's worth spending more money on special "3D printing" inserts. Since the last video really performed well I made another video on that topic in order to answer some questions and comments. This test covers M3 inserts and tests them in PLA and ASA.
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Impressive analysis committee and methodology as usual Stefan!
On your torque out test, the reason for failure of the bolt head is because you are torquing againts the insert itself, you could try using a longer bolt and thread lock it into the insert and use a washer to provide lateral support for the fastener head and shank.
In my practice most (if not all) of the insert are being pulled out from the opposite end - so "pull-out force" is not important, as printed parts (elements of HEVo) are starting to crackle ominously when screwing then hard :)
Also - by inserting M3 bolt from the opposite end while heating insert with soldering iron helps A LOT with keeping them straight. And I used only cheap ones so far.
Just a heads up, your M3 aliexpress affiliate link is broken.
There is a problem with the audio in the video, around 1:05 it cuts Your voice and then returns to normal after a second
Great video anyway :D
For me... your channel is the most important one for 3D printing. I say that because you address structural (as opposed to aesthetic) issues, and... you do it in a way that the layman can understand. There are other very technical 3D print channels, but they are useless to me. Their viewers would need to be advanced printers to know what they were even talking about. Thank you for the great work.
Agreed. I'm not a novice and this channel still has the best content. Some of the other popular ones all eventually devolve into "politics" of the 3D printing world - things I have zero interest in.
CNC Kitchen is the best resource channel for 3D printing. A lot of it applies for any printer on the market. I like makers muse is great for fun things to try. Or cool test prints. Bur cnc kitchen is legendary for data being pressnted in an interesting way
If you ever find yourself looking for thorough testing on household items rather than 3D printers, I highly suggest Project Farm. He tests just about everything. Tape, oil, ratchet straps, batteries, drain cleaner, tire sealants, portable tire pumps, nut removers, brush blades, windshield wipers, drywall anchors, the list goes on. Some tests are less scientific than others (the brush blades come to mind, lots of room for human error), but they're more than sufficient for how people actually use them. Plus he never accepts sponsorships.
@@The_Forge_Master however he has the personality of a small pencil.
Agreed. CNC kitchen will turn you into an advanced printer and you won’t even notice it.
I would think your major advantage to a threaded insert, particularly when you might choose the cheap ones instead of threading directly into plastic, would be for something that doesn't require great strength, but *does* require repeatedly removing and re-installing the fastener. In those conditions, cross-threading and wear would quickly destroy the threads in plastic alone, where the brass insert would happily withstand as many cycles as you'd wish to throw at it without appreciable wear.
Very interesting results, I expected the cheap inserts to be much worse, but surprisingly not bad in comparison. The raw plastic results were the most surprising, I didn't realize pla was that strong.
Thank you for the video, honestly only ever used the Injection molding inserts and just figured they were all about the same. One difference between how I use them and how you tested could make for a video idea. When I design holes, I make the octagonal rather than circular..... they seem to be printed more accurately in size, and since they are printed so small, there's little difference in the viewed shape made. Too that, I usually design object to accept the insert in from the rear or the part, the chase the threads with a tap. IDK if it helps with strength, but my thought was that I'm essentially trying to pull the inset through the plastic when tightened, rather than pulling against the direction of insertion.
The cheap ones I use where they can either be inserted from the back (with plastic surrounding the edge of the "top side") so that pull out is mitigated, or just for low-strength but frequent insert/removal. They work fine for that. Insertion can be easier if you add a slightly wider diameter on the hole leading in (again from the back size where possible).
Another good use for those inserts is making sure an overtightened bolt won't crack the plastic part it's in.
I am using the cheapest ones and they work for me. I don't need to pull that much weight and having many for near nothing helps me :) Mostly i use them to secure covers ect.
great engineering testing work. good presentation of the results. Liked your video very much.
Even though it's an older video, it's still very useful
Do you have a video showcasing your tensile material tester? It's quite impressive. I'm intrigued by its capabilities. I have a couple of inquiries regarding its operation. Typically, in engineering practices, tensile tests are conducted at a specified rate. In the medical device industry, for instance, we often conduct tensile tests on plastics at a rate of 0.2 inches per minute. According to a quick web search, the test range can vary from 0.2 to 20 inches per minute. You might find Table 1 on page 6 of ISO 527 and ASTM D638 helpful in determining appropriate test rates. Your testing apparatus seems quite efficient.
Regarding threaded inserts, the ASTM standard commonly employed is ASTM F606/F606M. However, it's worth noting that this standard does not prescribe a specific pull rate for threaded inserts. The selection of the pull rate should be based on factors such as material properties, intended application, and industry standards.
Another question I have pertains to the accuracy of your drill bit diameters. It's important to ensure that the diameter of the shank matches that of the head of the bit, which may not always be the case. Using a micrometer to double-check the dimensions is advisable to confirm precision. While pin gauges might not always be the best tool for this purpose, it's essential to verify the accuracy of the drill bits.
For metric threads, ISO 261 provides valuable information. For instance, the Major Diameter of an M3x0.5 external thread typically ranges from 2.874mm to 2.98mm, while the Minor Diameter ranges from 2.272mm to 2.439mm. The Pitch Diameter falls between 2.58mm to 2.655mm. The tap drill size for an M3x0.5 thread is typically 2.5mm, while for an M5x0.8 thread, it's 4.2mm. Your content is informative and engaging. Keep up the great work!
I would also like to have seen a comparison with a standard M3 nut pushed in to a hexagonal recess on the opposite side of the material. I think this method has the highest resistance to pullout.
Excellent video. Thank you very much for sharing your results. If you ever happen to do a similar test, self threading screws for thermoplasts would be interesting as well. I am having good results with these so far and they feel more solid than regular metric screws. If you need some samples, let me know and I will send some over - I live in Germany too.
I would love to see this test done with metal inserts in hardwood!
Yep, when I reverse engineer a stl part back into a solid (even my own old work where the original part file is gone) the holes are always smaller by about .1mm when dealing with 3mm-4mm holes. 5mm holes are closer.
Sounds like your software partitions larger circles into more segments when converting to a triangulated surface.
@hanelyp1 Happens with Solidworks to STL or any STLs I find on the net (meaning Thingiverse et. al.). I have YET to find a stl that precisely gives me the size of the original hole size and when I brought this up on the rep rap forum years ago the answer was because a stl can't do it no matter how many, or how few, triangles you slice it.
I think that the problem with short inserts is that you install them on the front side, while you should install them on the back side if possible.
1:56 these are what hold in your screws/bolts in a laptop, they're annoying asf if the things been dropped and the anchor point is snapped
Man, the pullout game looking strong for some of these. Better then some people I know!
Hmm..the cheap insert with a long screw to a nut on the back side would resolve the pull out limitation. Of course the cost of an additional nut and longer screw would reduce this $ improvement.
If anyone is watching this 3 years later, you can get Ruthex "clones" threaded inserts on AliExpress 50 pcs for around $1.5USD
if i need holes at a corner, how much space do i have to leave between the hole and the edge of the 3d printed part?
thx
Hey there the inserts i make in AUSTRALIA
A comment... the three designs shown should not have more than one or two cents difference. All are produced on old fashioned automatic screw machines. The external knurling form makes no or tiny fractions of a cent difference in cost to produce but big difference in performance.
Those "cheap" inserts appear to be overmolding inserts, designed to be held in place and have plastic flow around them. When you heat press those, I'm guessing a cavity is formed where the plastic did not flow and create the ledge necessary to mechanically lock into the plastic.
this is 100% what is going on. Those are meant to be in place at the time of molding, not added after the fact. That's why they don't have the lead in chamfer and they push plastic when you try to melt them in. They are not designed for this application, though they will work ok for light loads. When used in their intended application they are equally or more strong than the actual heat set inserts.
Perhaps it would be worthwhile to experiment with holding the soldering iron for longer to see if melting the plastic more helps with that issue.
agree
I just print the hole smaller than it should be and hold the iron for a bit longer. The only time such a part broke wasn't even in the place of the insert despite it being the place with the most stress applied
Was hoping you would try a pull through test as well as a pull out since that would provide the greatest strength for them all. I.E. insert the insert on one side but screw the bolt into the other.
Also, I wonder how well M3 wood inserts would work (if at all) i.ebayimg.com/images/g/2koAAOSwDoNd1PUd/s-l400.jpg
As an ex aircraft engineer, I've always fitted inserts from the back side for a superior fixing.
thank you for sharing you experienced tips :)
If that is a possibility, but if it is it will greatly improve performance. I would like to test out if it would be possible to insert them during the print with a pre programmed pause in the g-code for parts where that wouldn't be a possibility, though I think I'll run into problems with the bed level.
You mean so the thread goes from the other side through the plastic?
@@EGGSHL I think he means he'll insert it from the back side so the force on the end product will try to pull it further in.
not always possible but good when it is.
Whenever possible, threaded inserts should be installed on the side of the part opposite from where the fastener is entering it. (Obviously this isn't possible with blind holes) This preferred orientation results in the fastener pulling the insert even more securely into the part. It would be interesting to repeat your pullout tests with your test blocks flipped over. I've found that the plastic part will usually fail catastrophically before the insert is pulled out.
Thank you again. You're the only one who provides reliable, real-world data for this sort of thing, and it helps me when I design my projects.
Yeah- what Darrin said!
Now i wish I've seen this video 2 weeks ago, just had a project, where this would have been the perfect method...
Surprised that the direct “screw into plastic” method was so effective at pull out resistance. Performed just as expected on the torque-our test. Didn’t think it was going to be any good at that.
I did this with a bunch of M6 screws. I heated a screw with a small heat gun, and threaded the screw in to the PLA to form the threads. After the holes cooled, I stripped a couple of the holes by tightening the too much. The M6 threads are pretty deep, about the same as the wall thickness of the PLA. If I figured out how to create thicker walls around the holes than the rest of the model it would have been better. This video is great because I've wondered about which inserts would work best. Now, I wonder if the results would be the same with bigger screws.
@@microdesigns2000 Generally speaking, the bigger you go, the easier the pull-out will be, but the harder the torque-out will be.
I always just tap right into PLA with a tap set and never had an issue where those threads were the weak point.
I bought hundreds of brass inserts to use when the tapped threads fail...but they have yet to fail!
Was just thinking about fitting them into a pocket from the back, The back hole should be sized for the insert but the front sized to just clear the thread thus leaving a shoulder for the insert to pull up to.
Love the testing machine by the way
I'm using your suggested method whenever possible and it works very well even with the cheapest inserts.
Another potential depending on the design is to make a slot for a regular or square nut to insert them from the side. This essentially embeds the nut in the middle so it is as strong as your piece on pullout. The only issue that I've run into with this (mainly with regular hex nuts, less so with square nuts) is torquing, as the nut may spin through the plastic when tightened as it's only held by 4 sides. I've solved this by simply filling the slot by melting filament which securely locks the other sides of the nut in. Again this is definitely design dependent, requiring the ability to create a slot in the side of the piece to slide the nut in sideways, but it is definitely the strongest when it comes to pull load as the nut is fully embedded in the piece.
Absolutely.
@@newolde1 CNC Kitchen did some testing with steel nuts. Putting the nut in a bottom pocket gave over twice the pull-out strength over the side-pocket method! (165kg vs 85kg) Even threading a bolt directly into the plastic was stronger than side-pocket at 118kg! Helicoils and inserts were barely better than direct threading the bolt into the plastic at 120kg vs 118kg so inserts are a waste of time it appears. (maybe useful if inserted differently as some suggested here) There are some surprising results: ua-cam.com/video/2wRc1KbEAU8/v-deo.html
What? Quality bolts shearing at 3Nm? Uh, that shouldn't be, was the quality may be the machining but not the material?
It's hard to see in the video, but if those had an 8.8 stamped on them, and they broke at 3Nm, then either they are mislabeled, not-quality, or your Newtonmeter Wrench is about 1/3 off.
An M3 8.8 class bolt should not fail under 4.02Nm, but a 6.8 one, for example, is only rated for ~3Nm, 12.9 ones are even rated up to 6Nm.
Sorry, I'm an industrial mechanic, cheap mislabled screws on things is an annoyance i cant stand XD
I would be interested to see how this compares to having inset hex nuts instead. I tend to use nuts to fasten my prints together (similar to the construction of a Prusa) for ease of use since it doesn't require a soldering iron. I could be persuaded to switch if threaded inserts were significantly stronger though. I suppose this largely depends on the amount of infill used.
My guess is the nut will have a higher pullout, but would have lower torque out because it crushes the part. The threaded inserts are touching the bolt head when they failed in torque out.
Hi there!
I worked in the recycling industry for years and when we started to use 3d printed parts for our valve systems, we quickly banned all inserts. They just won't hold and become loose due to vibration. You can't loctite them and no other glue seems to work either. The solution was using square nuts in channels. They are not only cheaper but can also handle higher torques than inserts or hex nuts. I hope that helps!
Regards,
Etna.
Inset hex nuts are my favorite too, either installed after the fact in a slot or captive in the part by installing them during printing by pausing after the last layer before the hole is closed up.
There is also the question of square and hex nuts. I would guess that square work better in this application.
I haven't gotten around to using threaded inserts yet, mainly because I'm too lazy to go buy a new soldering iron lol but somehow preferred to buy hexagonal female standoffs. I use them in the same fashion as inset hex nuts, using friction fit to hold them in place and put in a screw from the opposite side so they stay put.
I've been using some I got from Adafruit and have found that, as I iterate, I waste a lot. Thankfully, I've found that you can actually reuse them if you screw a screw in all the way, blast it with a heatgun, and pull. Ruins the part, but if it's a failure anyway who cares? Just thought I'd share in case it helps anyone.
Good idea!
This is actually where the cheap injection molding inserts excel - they are so easy to pull out that you can reuse them again and again... -.-
For the next video
How well do embedding an ordinary nut compare
Good question. From experience, captive nuts perform better (when used on the reverse side of the part, or even embedded inside the part), simply because they have a larger surface area to engage with the plastic.
@@fredgenius captured hex vs captured square nuts!
They can be fiddly as hell, though.
@@fredgenius Your claim does not make sense with respect to the empirical data given. If you had the hot melt insert on the back side of the print, the plastic would again be the weak link. Look at what the inserts did in the last video when he had infill. The inserts were strong enough to blow apart the plastic well beyond their diameter. Having more surface area is a moot point when the weakest point is the surrounding infill.
@@Anyone700 As I said, it is my experience. Much depends on the material, and structure of the print, I suggest you try for yourself and form your own conclusions.
Thanks for making this series of videos. I, and probably many other people, find this information invaluable. I’ve always wondered if it was worth buying the more expensive, chamfered, inserts. Your videos are always quick, to the point, and well edited. Well done!
I fit them from the back of the part where possible, then they perform much better!
That's a great idea! You can even make so that the hole has a smaller diameter on the end. Awesome, thanks!
@@runklestiltskin_2407 You can also make insert hole with alternate layers smaller/larger, and glue the insert in with epoxy...
Same here. I fit them in through the backside and then pull them in ffom the front with a screw. So you don‘t need the space for the soldering iron.
@@timha4102 Yes, I use this trick to help get the insert square, so the screw is perpendicular to the surface. I use a long stainless screw so I don't burn my fingers, and easier to judge the correct angle.
thats also an idea that i thought About an had liked to see as a test
Sometimes we don't need a lot of holding strength but instead need the ability to insert and remove the screws a number of times without damage to the plastic. In this case the cheap inserts could be more than sufficient.
Did you watch the entire video?
@@TheMidnightSmith if you don't need a lot of holding strength the cheap ones are good enough.
Now that i know that cheap ones holds up to 30KG i surely going use then for hold up to 15KG...
if it has no chamfer then it's a pain in ass to work with!
@@KiR_3d you can maybe remedy this by adding a slight counter sink to your design.
@@LopezfsS Sure, but it can be hard to implement if you have thin walls (actual walls) for example. Then on one end it will have almost no grip.
I recognize those stickers at 6:56! Thank you for the feature Stefan! Also great video on threaded inserts!
I don't even have a 3D printer, but I think it's amazing that you did this test!
would like to see test of Screws that are specifically made to fasten into plastic, and that self tap the hole. Like those found on many consumer electronics.
They'd be pretty good for pull-out (dependent on length, obviously) and fairly lousy for torque. The holes also deteriorate quickly if you take the screws in and out.
I actually watched this video whilst buying threaded inserts (and stainless M4 pins) to replace the self tapping screws that hold on my car's pollen filter housing and can no longer be properly tightened.
If you will need to remove and refit the screws then self tappers aren't a good choice in any material.
Would be interesting to see case variation with screw directly to plastic, reasonably tightened, and performing the pull out test after some time: from my experience screwing directly to plastic suffers often from creep or material relaxation over time thus might not be a long term reliable solution.
Otherwise it was a great video, as usual! Cheers!
i model threads in the part in fusion360, with a little bit of chamfer on top, and directly screw in the plastic. In my experience, with 4 perimeters of 0.4 nozzle this is a rather durable connection, even after a half a year of screwing in and out 1-2 times a week threads hold properly, i just make sure not to overtighten them.
So, id be glad if you tested torque and pull-out force that this connection can withstand with differing amount of wear on it - perhaps, strength after 0 cycles, 10 cycles, 50 or even more
Also self-tapping and regular screws with no thread would be interesting.
Once I was able to snap M3 A2 stainless steel bolt when screwing it into bare PLA part with 100% infill and thread lenght 10mm which was created by first drilling recommended size of hole for tapping and then tapped it with the bolt itself.
Cheap injection molding inserts, completly useless, come out easily, get blocked at the end - so same results as you had.
More proper press-fit type inserts("eBay" ones) work well for me, but I don't use heat like you do, I drill smallest recommended hole for this insert, then press it cold, requires quite a bit of force, at least 50kg, but then stays in quite well.
Those special inserts "specially designed for PLA" yeah you're correct, those are inserts for standard plastic, didn't use them tho.
And yes I do drill holes in filament, it's stronger as you have solid wall instead of textured wall, it's too much of a pain in the ass to try to print exact hole size, depends on too many factors, too hard to control it, just design 3mm hole, it will print as 3.2mm then you just correct it with 3mm drill.
One thing to consider with the cheap inserts, well all inserts, with 4 inserts working together, like the fan mount, the cheap inserts would give you up to 156kg before they started to fail.
You should never rely on multiple fasteners to do the job unless one is strong enough by itself. The rest are just for support but all of the load will only be applied to one and not spread evenly.
Doesn't rarely ever workout like that in reality. It's also a very twisted way of thinking.
Those "Ruthex" Specially designed for 3d printing are just standard ones and can be bought everywhere and is not made by them lol!
Fantastic tests. I think what this tells me is that just driving the screws directly into the plastic is fine, unless you plan to repeatedly remove the screw and replace it.
The cheapy inserts need plastic to fill the recessed section between the knurls. Good for plastic injection, no good for printing.
I think you nailed it in this one. As tempting as it is to go with the cheap inserts for low strength applications, the amount of time and effort of keeping them aligned is a deal breaker for me, especially if i was trying to do a small production run of parts.
Great video once again. I would have loved to see the embedded-regular-nut technique too, that's my go-to technique. I would suspect it had very high pullout strength, but relatively poor torque-out strength, especially for small nuts.
For such a technical hobby the 3d printing community really does have a lot of folk wisdom floating around that is pretty much baseless. Its really nice to have these videos to provide some real information.
So true. DIY 3D printing is the poster child of Cargo Cult.
@@ArnaudMEURET When I got my first roll of PETG I spent the longest time taking pains to 3d print everything as one part because I had seen loads of people say it was near impossible to glue it. But one day when I was out a family member accidentally broke one of my prints and glued it back together. Turns out super glue works fine on PETG. I learned a lesson about 3d printing common knowledge that day.
@@outsider344 It kind of depends. ABS you can just partially dissolve with acetone and get perfect properties in the joint, as if it had been one piece (disregarding internal structure from infill). Super glue works well if you just want a stiff joint. If you are however using the flexibility of PETG properly gluing it is hard.
@@FreeOfFantasy I agree. But I had seen people saying you just can't glue petg at all. That they avoid printing it because the only way to join pieces is with mechanical fasteners. You do make some compromises with the material properties at the joint when you use superglue but that beats the heck out of having to screw parts together.
Those "cheap" inserts appear to be overmolding inserts, designed to be held in place and have plastic flow around them. When you heat press those, I'm guessing a cavity is formed where the plastic did not flow and create the ledge necessary to mechanically lock into the plastic.
so what is the best one?
SO basically expensive insert perfectly solve a problem that doesn't exist.
no ... an insert is way better, when using the screw very much. here he tested only first use, not long time use ;)
@@georghartmann6971 good point Mr. Hartmann, I however always screw directly into plastic (or to a nut behind it). Inserts are just not ever absolutely required, really, so I've never needed them..
damn that 0.1 difference is great. most printers I see make it 0.5~ smaller. mine used to do 0.3mm i think? i'll check again
EDIT: huh mine can do 0.1 too with ease. I was wrong this hole time....
Yeah 0.1-0.2mm is normal. More is usually holy overextrusion batman.
Mine was on point, though I need to put it back together with the new stepper drivers.
.... that pun...
you are a certain kind of hole. have my upvote.
Wonderful video. I usually use the under-sized hole method. I've also had success with regular M3 nuts thermally set into one side of the part. The measurements of having a nut thermally set in a hexagon pocket in the opposite end of the part would be interesting. This is cheaper than the Chinese brass injection molding inserts, and likely provides greater strength, due to the exposed diameter of the nut being supported by almost the entire thickness of the plastic.
You should test self-tapping screws next
MrStephan246 self tapping, press fit and screws designed for plastics. For a hobbyist heated inserts work fine, but for production they are slow.
I would be curious to see the effect of hole geometry on the pullout strength of the cheap inserts. For instance, you could try having a conical top to facilitate threaded insert alignment. You could combine this with a narrower diameter below the cone to help grab on the smooth ring of the cheap threaded insert.
Unfortunately the insertion path robs you of most of the freedom there. Because the bottom is flared out, the top is flared out; once you insert the bottom, you have displaced the material and it won't really fill the void around the waist of the insert no matter how you designed it originally, i would think, since the plastic is never fully molten.
Me too, I use the cheap inserts and found good results when reducing the printed hole diameter to something like 3.5mm . Yes it causes excess pla to ooze out when inserting but it definitely makes for better pull out strength. I suspect some experiments will show that its possible to make usable inserts with the cheaper type.
idk about other slicers, but Cura has horizontal expansion setting to deal with the printer-specific issue regarding to accuracy, so I can keep the CAD numbers without the additional compensation
This also has side effects though. Better to design the tolerance into the part. Especially when sharing. I just fixed a batman file that previously relied on using horizontal expansion.
I also use the horizontal expansion. I found that not only are holes to small but the part is to big equal to the amount the holes are different. This is also helpful when printing htpla parts. Once you know your shrinkage you can print exact fits.
I do not do the sizing by design because different plastics have different shrinkage. And it is easier to change in the slicer then to make multiple designs.
Stefan, I really appreciate all the testing you do. When I have questions about what I can get away with when designing for AM, you are my first source. Thank you so much!
Even those cheap tread inserts you can get for like $3 dollars for 100 of them will be useful. For things like making a box for something like a Raspberry Pi, custom cooling system for your 3D printer and other projects like that.
I never thread the plastic or use threaded inserts, I put a nut on the backside instead. This is far stronger than any threaded insert.
Also interesting how would rivet nuts work with printed plastic...
McMaster Carr has a huge selection of quality inserts for plastics.
No McMaster in Germany unfortunately.
@@CNCKitchen That sucks, McMaster Carr is such an amazing resource.
It would have been interesting how a nut in a hexagonal pocket on the backside of the part performed in comparison to the methods you presented.
I was thinking the same thing. I commented for square nuts, but any would do.
i hated these inserts my whole life. now I found out it was cause I used the wrong kind... I'll start using them more in my designs i guess xD
Super Video, Danke!Ich finde, dass das verwenden von Gewindeeinsätzen auch optisch was hermacht! Hast du schon mal probiert, teile mit einem 3D-Stift zusammen zu "schweißen"? Ich hab ein paar Tests gemacht und bin zum Ergebnis gekommen, dass wohl bei stumpfe Verbindungen V-Nähte mit viel spalt und bei T-Stöße mit beidseitiger Kehl-Naht ziemlich stabil sind. Könnte eine echte Alternative zu kleben sein.
In some cases you might put the cheap inserts on the other side of the piece in order to get better performance
There's a number you should hit for the hole size for threading into any material, for M3 it's 2.5mm. M4 is 3.3mm, M5 is 4.2mm. That allows the tap to cut the full thread. Smaller than that, you risk breaking the tap, bigger will compromise the thread.
Fred Genius I was wondering about this too. The hole was just tapped with the screw, so would a “proper” sized hole used with a tap be stronger?
Maybe not as the direct with a screw method leaves more material? Does the heat of tapping cause the PLA to melt a bit and form a wall thickness matching the threads?
I smell a sequel!
@@joshsekel I don't use this method much with printed parts, but in metal I always drill the right size hole for the thread. Metric threads have major and minor diameters defined (as all threads do), so for internal threads you want to hit the minor diameter as close as possible so there's as much material as possible to create the thread. The larger the hole, the weaker the thread. I always use a tap, by hand, so the heat generated is minimal. Although if you want to use a drill I don't see a problem - other than it's good to 'feel' the progress of the tap to avoid breaking it, especially on smaller threads.
If you directly screw into plastic you shouldn't go all the way down to the tapping diameter. During tapping you cut the material, directly screwing into the material just pushes it to the side, so if you do too small you will stress the part too much and crack it.
@@CNCKitchen I agree, but taps are cheap and readily available, why would you want to screw directly in to plastic?
Half an hour ago I looked on Aliexpress to order some M3 Insert Nuts XD
Well, contextual content production is definitely better then contextual advertising.
Good news everyone.
Now you can buy inserts similar to Ruthex for less than 5$ per 100 pcs.
aww hell yeah. I was hoping you'd do a video on this. You do such great breakdowns.
You will get MUCH better (best) result with any of these in case if you will use it from opposite side of hole. Viele grüße!
I was wondering about the pullout strength of bolts heated to 210 degrees C then screwed directly into PLA. It seems like this would give higher pullout strength because the PLA can flow more fully into the thread form. Another brilliant video Stefan.
When I need, I insert square M3/M4 nut into print
Those are not quality screws if they shear off with that cheesy torque wrench. That is absurd. Are those screws made of zinc? You should not be able to shear off screws like that with an impact wrench in plastic. Stainless steel screws none of that Chinesium bullshit. Powder molded metal is pure shit.
awesome video once again. I finally supported you on patreon, I'm happy to help support your fantastic videos!
Thank you very much for the support! Highly appreciated.
You'll probably get more useful torque test results if you were bolting down a stack of washers rather than just the bolt. The longer exposed thread of the screw will be allowed to stretch and load up the insert properly
Outstanding work lad!
4:47 I have spotted the deathly hallows
Hallo mein Kollege ausm Schwabenländle ;)
Hast du dir auch mal die Gewindeeinsätze von Multisert angeschaut?
Mit denen habe ich vor einer Weile Zugversuche in Multijetfusion/SLS-Teilen gemacht und ich war wirklich sehr positiv überrascht!
Wir haben davor immer Gewindeeinsätze verwendet, welche eigentlich zum Einlegen und Umspritzen bei Spritzgussteilen gedacht sind...
Viele (vermutlich sogar nahe) Grüße
2:40 - chamfer the hole
my thought exactly
I would like to see it again with stronger screws.. or with softer 3d print.. like.. i dont really care what is the max strenght of the insert, just which is better for torque
You don't get stronger screws. Even 12.9 steel M3 screws are only specked to 2.5 Nm. However going up a few sizes would work. A doubling of diameter gets you about 10 x the torque.
Stefan, thanks for the research!
Excellent research, test results and presentation. Video could not be improved, well done. Thanks from Colorado.
As someone said here, what if you insert the inserts from one side and pull them from the other side ? The AliExpress parts would probably be the best this time !
“Quality screws” shearing at 3-4nm?! Haha no.
They arent bad but still wouldnt call them quality
Yes, that was very odd.
M3 screws are not that big. A random screw calculator at www.amesweb.info/Screws/Metric_Bolt_Grades_Strength.aspx gives 2.1 Nm minimum for the best 12.9 grade, so these are quality indeed IMHO.
You forgot to mention that screwing in without an insert isn't always a good idea if the hole is on the layer-line side of the print.
I’m wondering, what if you twist the insert while inserting? Would that be good or bad for the cheap inserts?
I've used the "cheap" ones when working on a injection molding machine.
Hi, thank you for the tests! It's really interesting.
One point though, are you sure about the torque values? 3 Nm doesn't seem much to break a screw, but maybe I'm wrong because I'm more used to m6 or m8 screws which can handle more.
Hi,
I use the cheap ones for when needed. More like multiple loosen/tighten threads. Because pla wears out.
But I have another approach.
I make the hole slightly smaller.
Heating up a little and then pull them in with a bold on the other side. Not completely through the hole and a little plastic in front so it's locked up. And before pulling it in a drop of CA glue.
Maybe you can test something like this too.
Yesterday I saw your epoxy / CA glue video. I also thought CA would improve strength between layers but turns out it doesn't.
For expoxy I use Z-poxy but probably much more expensive then HK.
Although it less yellow I think.
After a while it still colors yellow due sunlight.
And try some carbon fiber or glascoat with CA instead of epoxy in your next test.
Keep up the good work.
Great work Stefan ! Perhaps you would consider testing a Helicoil insert thread as well ? Helicoils should have the advantages of a plain tapped thread, but with the additional strength of a larger diameter thread.
Is there a dataset somewhere of the different fixtures breaking points? Including things like the square nut Prusa use? Maybe a useful community resource.
TIL Germans are good with inserts, but pull out game is also strong.
I have the cheap Ali inserts. Mostly for items with repeated screwing and unscrewing with little pullout load.
I also design a small indented circle that works with the outer diameter of the insert as a position guide. I also modified a soldering tip to have a cylindrical tip that fits into the insert to keep it aligned and stable and improve heating of the insert.
Für das "glei krachts" gibt's nen Daumen 😅
Der Rest des Videos ist aber auch sehr gut ;)
Excellent coverage Stefan, I will definitely keep this in mind if I need to use inserts. Cheers, JAYTEE
My dad failed the pullout test
Das ist genau das Video das ich brauche. Ich baue Mäuse selber und die Schalter in den Tasten machen immer Probleme
You do such amazing work, and you showcase everything so well in your videos! You are awesome! Thank you! :D
Is 2.7 mm for the undersized hole the nominal or the actual diameter?