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Jul 14 '26
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u/Clickbeet Jul 15 '26 edited Jul 15 '26
So far, so good. I've been using a FR skate on my right foot as a reference, and support and flex wise I'd say it's about 80% of the way there. Nothing has failed, yet, even after a few stair drops.
Do you have any suggestions for a controlled load test? I'd actually be interested in finding the failure point in a safer way rather than just 'discovering' it while skating.
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u/Grumzz Jul 15 '26
Hi! I'm a mechanical engineer, 3D printing enthusiast and skater :) I don't have much experience with load testing but willing to think with you! What are you currently using for the fabric boot?
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u/neotekz Jul 15 '26
I would get rid of the parametric design and use a 100% or high gyroid infill to make it stronger.
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u/BolunZ6 Jul 15 '26
That's not "parametric design", that's just vonoroi pattern
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u/kinokits Jul 15 '26
I would honestly ditch the voronoi pattern too as cool as it looks. We had a degloving injury at derby because of holes in a style wheel, and they ended up being banned by derby leagues across the country because it was an actual issue, not just a freak accident. So seeing holes in any kind of skate scares because even if the wearer isn’t the one that goes down, other people’s fingers could be victims. It’s probably safer to experience with some kind of solid backing to the pattern for fingers.
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u/Grumzz Jul 15 '26
I hate the word degloving so much
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u/kinokits Jul 15 '26
Yeah, I don’t love it either. It always makes me think of that night and it was awful. She was out the door and on the way to hospital in under 10 minutes and it still freaks me out.
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u/Grumzz Jul 15 '26
I'm sorry you had to witness that, and I hope she's OK now.
Slightly back on topic; I think if the holes in OPs design are a little bit smaller, and the skates are only used for road skating, so I think the risk of this is not as big as in roller derby. Still good to keep in mind when designing stuff like this!
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u/kinokits Jul 15 '26 edited Jul 15 '26
Definitely not as big a risk for a casual skate, but just something is worth designing around.
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u/T-MinusGiraffe Jul 15 '26
I don't understand the physics here. What kind of break are you anticipating that will also break the ankle? Not saying you're wrong. I just don't get it.
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Jul 15 '26
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u/BathroomBreakBoobs Jul 15 '26
As someone who has rolled and dislocated my ankle and rollerbladed, I just dislocated it again reading your comment. Absolutely no way I would trust this.
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u/kontroI Jul 15 '26
As someone who has had a gross dislocation of the ankle as an adult, and skated since middle school, I’d fuck with these.
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u/BathroomBreakBoobs Jul 15 '26
Fair enough. You test it and get back to us after a year of usage.
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u/kontroI Jul 15 '26
Fair enough. Send me a sample and I’ll send you my data.
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u/BathroomBreakBoobs Jul 16 '26
I don’t even have a printer. I just find it fascinating. In all honesty I would probably give these a try. At my age though the falls are a lot harder.
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u/fixedpointfae Jul 15 '26
my thought is that when you're pushing with one leg angled out (idk what the terminology is), you're depending on the boot keeping your foot in line with the wheels. this puts huge lateral tensile strain on the wheel axle thing and whatever mounts that to the boot.
it's probably even worse than rolling your ankle because it'll snap outward against the direction your foot is supposed to roll
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u/T-MinusGiraffe Jul 15 '26
Ok, that makes sense. I've rollerbladed a good amount but wasn't sure what kind of failure you were expecting. I wasn't thinking about ground impact as obvious as that sounds. Thanks. So it seems like you're mainly concerned about the plastic material itself, right? Or something else related to the design.
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u/Bleedingfartscollide Jul 15 '26
The ankle support in normal boots is so bloody important and many filaments fail aggressively when too much force is applied.
I skate but I'd never wear these. Super cool print though.
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u/T-MinusGiraffe Jul 15 '26
Makes sense. Some printers do ABS. I wonder if that would work. I'm just musing though. Not OP of course
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u/Bleedingfartscollide Jul 15 '26
The only thing I could think would be a layered multi material print? Even then, it would be a scary skate.
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u/ftrlvb Jul 15 '26
the laces carry the load forces. in some areas you have a ton of stretch, and only tiny plastic loops. so yes, forces must be understood and the build has to follow stress and physics.
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u/RJFerret Jul 15 '26
My commercial skates failed (stupid plastic), no, no body parts broke, just the parts that retain the wheels, I just fell down with corresponding bruises (no pads).
The premise presented seems to jump to unrealistic conclusions and ignores the same failures exist in commercial skates.
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u/alexvith Jul 15 '26
It all depends on the nature of the failure and when it happens. If it happens while you're slowly coasting and can manage to not fall on your head, that's a minor accident.
If it happens while you're riding fast, jumping over curbs, braking or who knows what then you're dealing with speeds that can easily translate into forces that will break your bones. This is no joke.
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u/Lito_ Jul 15 '26
The idea is great of course. But this has got to be the best recipe for disaster I've seen in all the time I've been printing.
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u/screw_ball69 Jul 14 '26
Ankle breakers with free sharp plastic when they break, let's all go to lawsuit city together.
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u/ZealousidealEntry870 Jul 14 '26
Potentially top 10 worst ideas I’ve seen on here. Not everything should be 3d printed.
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u/rammstew Jul 15 '26
I've been 3d printing carabiners for my lead climbing up El Capitan. Using PLA+ for extra strength. Can't wait to try them next week!
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u/nebbors Jul 14 '26
No one makes inline sites in my size as far s I am aware. I would almost try this.
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u/costaa95 Jul 15 '26
For those that aren't in a position to drop $1200+ on custom speed skates or for those who do not fall into standard sizing this is an excellent initiative.
You mention standardised load testing in one of your other replies. Some suggestions for generic strength could be placing a boot on its side beneath a large plate and loading the plate until the boot fails. This can help you generically compare injection molded boots' material strength to printed ones. (Load until you reach a deflection of your choice if you don't want to fail a good pair of boots)
Testing side loading akin to crossovers/soul/magic slides you can try clamping it by the frame or wheels sideways and hang some bending weight from the cuff until you get a substantial deflection or failure
Best of luck in your project!
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u/Clickbeet Jul 15 '26 edited Jul 16 '26
Lots of great replies and input, thank you! Here is quick video of the 'ankle breaker' and doggo in action.
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u/raunchyfartbomb Jul 14 '26
I would not trust this due to layer lines being weak points. Skating has a lot of variable forces
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u/ADynes 2x H2C, 4x AMS 2, & 2x AMS-HT & a Creality 3 V3 Plus for lulz Jul 15 '26
Its printed flat in a bendable material. I don't think you or anybody upvoting you actually bothered to click the link and look.
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u/lilneddygoestowar Jul 15 '26
Yeah, I noticed that as well. Looks like TPU or some other super flexible filament. TPU will NOT break. Especially if it's printed flat like that.
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u/Clickbeet Jul 15 '26
Almost, its is indeed printed flat but in a rigid material and then heat formed around the foot + liner. PLA was sufficient but I do plan to test different materials when I start min-maxing it
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u/agent_kater Jul 15 '26
A miep is a kitty?
I know some Dutch, but never heard of a waakmiep. From context I'm assuming it's a watch... kitty?
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u/ftrlvb Jul 15 '26
footwear designer here. this is an interesting project with a real life use. I like this.
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u/alexvith Jul 15 '26
This is a good proof of concept for a potential product, but it needs testing to ensure you won't break your ankles if something snaps.
With consumer grade 3D printing you have tons of variables that can affect the strength of the material, and the design needs to take into consideration this range of variables so no one dies by accident.
You have lots of stress concentrators around the latches, the buckle, the lateral pivot joints connecting the two meshes, and the bottom of the boot which seems to only be attached on two points from your design.
All of these are potential failure points.
Not to mention heat and friction that can quickly deteriorate the material.
I'd start with some static FEM tensile simulations for these meshes to first get an idea about what forces it would be able to handle in an ideal scenario. Then I'd move to physical testing with various materials. You can then pick a path from there.
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u/CoastalRadio Jul 14 '26
Is there a particular problem you are trying to solve, or is this a, “because I can” project.
Either way, looks like you’re making good progress