When you think of “car rim” you probably think stamped steel or machined alloy with a sturdy drum to withstand the arduous life of the road, not something 3D printed out of ABS. That would be crazy, right? Not to [Jón Schone] from Proper Printing, who’s recently released an update about his long-term quest to outfit his older sedan with extruded rims.
There were a few initial attempts that didn’t go as well as hoped. The main issue was layer separation as the air pressure would stretch the piece out, forming bubbles. He increased the thickness to the absolute maximum he could. A quick 3D scan of the brake caliper gave him a precise model to make sure he didn’t go too far. He also couldn’t make the rim any bigger to fit a bigger wheel to clear the caliper, as he was already maxing out his impressive 420 mm build volume from his modified Creality printer.
A helpful commenter had suggested using a threaded rod going all the way through the print as a sort of rebar. After initially discounting the idea as the thickness of the rim gets really thin to accommodate the caliper, [Jón] realized that he could bend the rods and attach the two halves that way. Armed with a paper diagram, he cut and bent the rods, inserting them into the new prints. It’s an impressive amount of filament, 2.7 kg of ABS just for one-half of the rim.
It didn’t explode while they inflated the tire and it didn’t explode while they did their best to abuse it in the small alley they had selected for testing. The car was technically no longer road legal, so we appreciate their caution in testing in other locations. In a triumphant but anti-climatic ending, the rim held up to all the abuse they threw at it.
We’ve been following this project for several months now, and are happy to see [Jón] finally bring this one across the finish line. It sounds like there’s still some testing to be done, but on the whole, we’d call the experiment a resounding success.
You wouldn’t download a car!
But you might get away with just the rims.
The age old question with using most plastics is creep and thermoplastics like ABS might well get toasty enough on long high speed trips or under heavy braking to be rather uncomfortably close to or even over their softening point, probably safe enough in the cooler nations of the world there, but anywhere the ambient air temp is high and the road surface sun baked for extra heat…
I really doubt such a thing would stand up long term to the rigors of real use, and I’d certainly not call it safe, but I’ll admit its damn impressive they manged to get it working at all. Rather proves to all those that still doubt if 3d printing can ever print useful parts that it can – one of, if not the most impressive real world strength test of a somewhat practical print I’ve seen.
I’ll be more impressed if they even stand up to distances and speeds seen in this test, which they’ve probably got a 50th of the development time into … https://www.youtube.com/watch?v=MWVeXvZAP70
Very impressive experiment but as you say it lacks thermal stability.
I see a number of thermal problems –
With use the tyre flexes generating heat and transferring it to the ABS and the air inside.
Transferring heat to the ABS is an obvious problem.
Transferring heat to the air inside will increase tyre pressure to increase and increase strain on the ABS.
More importantly – Brake calipers preform the function of converting huge amounts of the cars kinetic energy into huge amounts of heat and transferring that heat to the air. There are two problems here.
1) A lot of heat is going to be transferred to the ABS as it is so close the caliper. At some stage the ABS is just going to melt if it hasn’t already failed in some other way due to the heat.
2) The caliper and therefore the braking system is not going to preform properly or potentially even unsafely as it has insufficient clearance to transfer the heat generated to the air. This is especially going to be a problem with only one ABS wheel as it’s going to cause a breaking imbalance that will cause the car to rotate or spin when brakes are applied after a number of times, especially if the ABS wheel is on the front. I hope they consider that before further tests so they are prepared and look for the symptoms.
Ideally the test wheel should be on the back so that it doesn’t cause steering failure when it collapses.
Overall a great experiment. Those “melt in” nutserts (or whatever they’re called in your country) were never going to hold that amount of lateral pressure even if they bonded perfectly to the ABS, the ABS would tare apart as there simply isn’t enough contact surface area and ABS volume.
The bent thread rod (all thread) is prone to metal fatigue due to the bend. Though by far that is not the weakest point of the setup.
Some military now use airless tyres (all composite materials with no tube or any pressurised air cavity) and getting this tech to civilian domain would save so much waste.
Old car tyres are one of the hardest thing to dispose of without harming the environment. When simply the tread of the tyre is depleted the rest of the tyre is still OK, sidewalls, radial steel belts, air seal, bead etc and yet we have to through the whole tyre away.
Making tyres out of recyclable materials would be a huge step forward.
I dunno, I’ve lost ~60% of my tires to sidewall bulges and weather cracking, before I’ve got the last 20,000 miles out of the tread. Some at only half tread life.
The caliper being near the ABS plastic isn’t the real problem. While the caliper does pick up heat from the pads and proximity to the rotor, the real danger is the wheel is directly bolted to the disc rotor which is where the majority of braking heat is going. Not only is the plastic going to start melting/extruding at the rotor contact point, the wheel studs/bolts are going to lose clamping force and the studs themselves are going to start melting through the wheel.
If you had a Jag or related with inboard brakes, this would mitigate most of the melting problems.
And the plastic wheel would be as reliable as the rest of the Jag.
Who am I kidding…it would be the last part working.
Tire pressure doesn’t change that much. With a correctly inflated tire, there’s normally around 4psi between cold and fully warmed up. If the tire is underinflated, there’ll be more heat, and more pressure rise, but with a lower starting point, it doesn’t matter much.
Heat and pressure rise can be a problem with road bicycle tires on long descents in the mountains, but that’s because of rim brakes, where the heat is going directly into the rim, and quickly into the air and rubber behind it.
https://www.engadget.com/2019-07-02-volkswagen-type-20-concept-microbus.html?guccounter=1
The Volkswagen electric type 20 has generative designed wheels and lots of other parts. It looks great how well it holds up is another matter. They are metal though but nevertheless 3d printed.
Metal wheels not only stand up to the brake and tyre temperatures, they provide a giant cooling fin for the brakes and bearings. I’d say plastic was a stupid choice in this application.
This is YouTube, where people test out crazy choices all the time, sometimes intentionally.
If your goal is to get a usable part, this is a bad idea. If your goal is to learn more about pushing the limits of 3D printing technique and materials, it makes sense.
I don’t have a 3D printer (yet…) but I already have had problems with layer separation – on a product I purchased (a bicycle bag bracket). Good in compression, bad in tension and probably shear forces. Just like concrete, well sort of.
Its not quite that simple with 3d printers – some filaments bond really really well layer to layer easily, others not so much and your printers calibration for that material, and how well you stored that filament can matter a fair bit too. Even a pretty small change in environmental conditions while you print can screw it up and entirely ruin the print (some filaments are terrible for this for one reason or other).
The layer line geometry always has some effect, but its not always that clear cut on weakpoints either, as so do factors like wall count, infill pattern,type and density. The failures can easily happen without any layer separation with the right (or rather poor) part geometry and loading.
Typo: “A quick 3D scan of the brake caliper came him a precise model…”
should be: “A quick 3D scan of the brake caliper gave him a precise model…”
Probably neither lol.
There was no load on the hub when he scanned so the wheel bearings were relaxed.
There’s probably some ware and play in the wheel bearings that when under load cause the caliper to contact the wheel.
Congratulations guys !!!! You definitely needs my car jack…..!!!! My rim have failed, exactly like your first one !!! https://www.youtube.com/watch?v=T33RTACFyPs
now that is impressive
I wonder if it would give you a better result to go with PLA as the negative to make a carbon fiber wheel…
Can’t wait to throw these on my 4-Rimmer, and maybe one for my Rim-barrow too
Jon is a very talented Engineer . Well worth following. His outstanding videos and humor on 3d printing are awesome .
Also I love His background music. I have built several of his upgrades and learning his own 3d printer controller. Next the portal printer.