Why dont you stagger the bolts so half of the bolts are going through each part which will improve the shear resistance on the other part? That would fix the issue without needing to print in a more expensive matterial.

I have an idea for a video to air with you, if you don't mind. Its takeaways would IMO be useful and relevant to your project, so it's not a sidetrack. I believe your style, creativity and production quality would be very well suited for such a content piece. I apologize if this is a bit messy and long; I'm just impromptu dumping a brainstorm on my phone here. If you find the time to read this, I thank you for that time. Super-TL;DR Install hot inserts into printed test pieces, and split them open to explore how (well) the plastic actually conforms to the inserts. - Brainstorm bulk dump: Inserting a few different common types of brass/threaded inserts into test pieces, then splitting the piece open to see what kind of material conformity and friction these inserts actually have to work with in terms of "hanging on". Depending on the scope, maybe at a couple of didfferent temperatures and a couple of different FDM materials? I would suggest designing the test pieces with two designated weak lines for easier splitting (just not so weak it expands or gives out when installing the inserts). Probably end up making the lines at 90° angle in a cross formation centered on the insert hole, in case the insert won't easily "release" a full 180° "clamshell" around it (but try 120/180° or something in between first, it would provide a larger remaining surface area to study in case some material must be cut to free the plastic part from the insert). Ideally you'd want the split section of the test piece to come away from the insert without breaking whatever plastic conformed to the insert's outer shape, so we can get best possible view of how the melted plastic actually conformed to the insert. Maybe use a small drill press or mock up a simple jig, so that you can get insertion angle and pressure fairly consistant between the samples. Maybe consider making 2-3 extra samples of each test group, and send them to Stefan for testing pull-out force, make it a channel/maker coollab 😃 I don't know if you have one, but IIRC both Stefan and Thomas Sanladerer have 3D scanners - if scanning both the inserts and split test pieces, you could make a 3D render showing even better how the plastic conforms (or doesn't) to the insert. AFAIK channel collabs like these are always cool and fairly successful content, and they amplify channel visibility for both/all creators participating. And seeing how IMO the information learned could actually be _very_ useful information for the 3D printing community, that information would reach wide, and the videos would likely sustain views long(er) term. I believe that the results and reflections from these tests would be very valuable in understanding the material dynamics at work, the strength and weaknesses of these hot-melt-inserts, and inform both 3d model part and hot insert design, to better work with and around those strengths and limitations. Most non-engineering tinkerers seem to think of it like the molten plastic conforming fully to the outer surface of the hot insert like it might with _injection molding_ around the insert, but I doubt it does that fully when "just" pressing one in hot. Surely some amount of the plastic will deflect away? There's still, relatively, a lot of tensile strength, surface tension and quite moderate viscosity to molten plastic, and almost all the pressure you exert when inserting one of these are "pushing the plastic away" from the insert. There's not much pressure involved to force the plastic in between the ridges and knurling of the outer shape of the insert, just fairly light back pressure from displacement as long as the bottom of the hole does not give (yet). To my understanding, this is why injection molding is done with substantial pressure, not just gravity fed - it's not smooth and easy flowing, it won't easily conform to small, high friction shapes without being "squeezed in there" with significant pressure.

@@pr0xZen wow, thanks for sharing your thoughts! The inserts I use are these www.onkenhout.nl/pdf/multisert_zonder_kop/227/t/p which are, unless most inserts you can find on the market, made for pressing in. It's definitely interesting to do more tests with these. At this moment I think that this is the best option I have considering the tight space I have. Threaded rods all the way through don't fit and nuts are too large and cause sharp edges which can cause delamination. This, together with the fact that the rim held more than twice the air pressure I think that I leave this design for what it is now until it fails at the next test. A very interesting thing which I can check though is the strongest way to add inserts. I always assumed that the best way was heating up, but at what temperature or maybe ultra sonic or just cold pressing is stronger. Thanks again, your comment gives new ideas!

Add a hub extender, and you would have way better results printing the entire rim and taking it to a tire shop for mounting

Thanks! Awesome, I'm proud of this thumbnail xD

@@properprinting go to a +1 wheel and tire size. Increase the wheel diameter by one inch and change the tire aspect ratio so the tire diameter stays the same or close to it. Then you'll have room for bolts all the way through. Instead of lug nuts with a bevel, use ones with a large and flat clamping face and a cylindrical locating section. That will add strength and centering along with the raised hub center. Next thing, put a chamfer on or round all the sharp edges on the spokes. The sharp edges act as stress concentrators. You can see that "hot spot" on CNC Kitchen's stress analysis.

@@greggv8 Thanks for your suggestions! The printer is completely maxed out with this design because the size is reduced due to the liquid cooling 😅 If I chamfer those edges there will be less surface touching the print bed and this print was already very close to warping. I think that there are other parts in the rim weaker than these sharp edges and I'll keep the design for what it is right now. It prints well, held more than twice the amount of pressure (which most people didn't expect) and we'll find out what fails next at which point ;)

That's what she said.

Safest way to relieve pressure at that point is to allow failure In a controlled manner

Thanks! I just wrote it down ;)

Also... it was really the inner tube that failed first so there is that, your mod would probably be a minimum requirement to handle side loads when actually driving though...

Agree, these inserts are supposed to be on the outer side.

Thanks Vincent! Probably the safest place to bee will be inside of the car xD I've worked often with lathes before and a big fast spinning clamp is something hard to get used to haha

Haha I've got the similar feeling when I hear the Norwegian language🤣

@@properprinting That's so cool 😃

Awesome Brandon, thanks!

I hope that we get to the point that this is going to be a point of failure ;)

That is actually a great tip! My mind didn't function that well at that moment😂

@@properprinting just disconnect the hose from the compressor lol dont overthink it

When you do wear some heavy duty headphones / ear protection. Releasing air that fast makes a deafening hiss(source I get to hear that deafening hiss weekly)

There's a T splitter, connect a third hose with a valve to it and extend it after the valve with a little bit more hose and wind the tip of the hose with cloth or acrylic wool, You wont hear anything at all, you can wind the over pressure protection valve and it will release air super quietly when you pull it's test.

You can also just shut of the air compressor and crack the bleeder valve on the bottom of the tank then let the whole system decompress.

Thanks! Working on it😁

Thanks! I think it would be an interesting test to see at what torque it'll be pulled out

@@properprinting also I as thinking the vibration from driving would cause stress fractures on the layer lines.

Thanks!

Bedankt! Nee, ik heb hele toffe buren (en heb ze vooraf gewaarschuwd ;))

The tube doesn't have a pressure rating as it's basically a balloon that's filled to take the shape of the container, in this case the tire and rim. So something with either the tire or rim must've failed, unless the tube was defective or the valve separated, the latter of which wouldn't normally end in a dramatic explosion. It's likely the pressure from the inflated tube caused the wheel to fail, specifically the plastic to separate and let the tube rupture there. Either way, you have to admit it's pretty impressive. I didn't think a 3D printed wheel would be able to handle all that pressure, both from the inflated tube and the weight of a car on top of it.

That's a good question! I use a different type than what you normally find on the internet which are specifically made for pressing in www.onkenhout.nl/pdf/multisert_zonder_kop/227/t/p These are the strongest the way I've placed them. For the next version I can make the holes a bit deeper so a collar is produced when they start to give.

Thanks! I initially designed it with the bolts all the way through, but there's not enough room between the edge of the tire and the brake caliper so I had to get rid of it unfortunately.

Yeah, u mean they should have used rods that goes from one side to the other side of the rimm to work against delamination of the layers?! That was my thought at the first vid...

I'm thinking vibration and bumps will give a separating layer failure. I think once the rims are printed, then we will see a "dip" of some sort for layer integrity. Know a great compatible hardening layer?

Hahaha xD

Haha awesome! Inserts are easier and for now strong enough ;) I'll improve things once that'd be necessary

@@properprinting or epoxy the inserts in place?

I would also think thread rods epoxy in inner side part to inner edge, will also improve layer adhesion, and then capped nuts on outer rim 🤔🤓

Awesome! I'm glad you felt what we did :D

@@properprinting oh i definitely did :D bachelor thesis could wait for this

@@pringineer1027 good luck with your thesis!

Cheers man! I am like 70% done :)

You were close! The space between the edge of the tire and the brake caliper is too small for threaded rods. For now this result is good enough to proceed and I want to focus on printing the side in which those inserts are placed out of stronger material if it needs improvement.

Thanks for the tip! We intentionally used air because we wanted to experience how violently this actually was. This way we know what we can expect when it goes wrong while being under the car. Turns out that, unless you place your head firmly against the rim, this isn't life threatening and we'll use ear protection for the next tests xD

Good question and would be interesting to put to the test! For this rim, the weakest point is at its parameters where there isn't any infill. The infill in this design isn't doing that much.

Awesome, thanks for your sub! I'd love to have a slow-motion camera. That crack for sure was close to the maximum strength of those inserts ;)

That doesn't fit like I explained in the video

Bedankt! Ik denk dat inserts, en vooral dit type, sterker zijn dan moeren omdat er niet veel ruimte is voor een moer en er veel krachten ontstaan onder het oppervlak van de moer tussen lagen in. Een insert verdeelt de kracht beter.

That could be the reason indeed. I've thought about that, but the problem is that the print volume in the Y-direction is reduces due to the water cooling. I completely maxed it out with this design xD

@@properprinting Heh. Does anyone make a light weight brake kit that has smaller rotors and calipers? Maybe from a smaller car that uses the same hubs?

That's a great idea and would work wonders but wouldn't it detract from the original purpose of this project?

@@SonofTheMorningStar666 no success comes without adjusting or outright compromising original assumptions to get a viable result…. Layer adhesion is a critical issue in structural 3D prints. Unless you can design around it, you must mitigate to get a safe result. You certainly wouldn’t want the outside part of the rim to come off in a slightly more than sedate turn or after hitting a rut in the road…..😱 I still really like the idea and the process you’re going through to get to a viable result….just doing my engineering thinking while enjoying the process.

@@CCCfeinman55 🙄 Give it up Chuck.

@@SonofTheMorningStar666 oK.

I have and I might have an interesting approach to realize this! :D

Thanks for the suggestion, but that's not possible as I've mentioned in the video.