AT-One electric inline skates (quick update Dec 2020)

[Vanarian]

Okay, after almost 2 weeks of fight prints are at it again!

So for the quick updates : Starting today I'll give a try to PETG filament, good alternative to Nylon as it has close to same tensile strength, is LOT more rigid, offer colors and is cheaper while still being easy to print.

I broke 2 frame parts today while stressing them with metal snaps, so I must improve design again (my hub rims do withstand the snaps, so the rest must be of same caliber)!

Flat frame is also under rework, I'll bring it soon. Soul plate has advanced, after making it less and less thick (ballpark is around 36-40mm thick now, same as some non-electric aggressive soulplates models!) I'm figuring how to make it just wide enough to be optimal. Hard thing to do!

 

[grindz145]

wow 40mm is a thick soul plate. What skates have a soul-plate this thick?

Maybe the old Varsities which essentially have 2 souls stacked on top of one another?

 

[Vanarian]

Well it depends, my Roces M12 soul plates have a variation on thickness, it is a hollow model but thickness is between 10 and 50mm

Razors soul plates are minimum 35mm thick I think and same for Xsjado, soul plate size varies in thickness.

But that's still on the big side you're right.

 

[grindz145]

Well on average the stock skates have a thicker sole that I thought!

P.S. just realized the irony of that traditional rollerblade spelling of soul...

It's blade night tonight, will be dreaming of motorized blades

 

[Vanarian]

What is blade night, like your city 's roads are open only to skaters?

 

[grindz145]

Naw they just have a reduced-price halfsession at the indoor skatepark. But it's fun because a bunch of folks show up.

 

[Vanarian]

I hope some event like this was in my city too lol, there are 2 skatepark and both are not easy to access... looks like my town mayor's priority was not focused at all on riders

Ok updates of the day :

I got my first 1kg PETG spool shipped! Gotta try and print something out of it

Also great new for a future DIY kit once I'm done guys, I've successfully squeezed 2x 12S2.2Ah of Turnigy Lipos in my slimmed soul plates So for Lipos lovers, that's 12S4.4Ah or 6S8.8Ah (bit more than 200Wh) of power and range! It is getting better and better

 

[grindz145]

Also great new for a future DIY kit once I'm done guys, I've successfully squeezed 2x 12S2.2Ah of Turnigy Lipos in my slimmed soul plates So for Lipos lovers, that's 12S4.4Ah or 6S8.8Ah (bit more than 200Wh) of power and range! It is getting better and better

nutz . Make sure you have a way to get them off your feet quickly! :wink:

 

[Vanarian]

nutz . Make sure you have a way to get them off your feet quickly! :wink:

I'll try my best! Also I'm stilll experimenting on the fireproof / impactproof foam i got from Rogers, at least if I can't successfully make a quick release system the foam wall + aeration holes should provide enough protection/time to allow the rider to get his boots off his feets before being harmed :wink:

 

[Ryuudan]

your frames do seem futuristic. I hope you can test them on the road soon. I was going to use PETG as well if my printer was able to use it. Or the carbon fiber printer if I had the budget hehehehehe

great job squeezing 200Wh. I'm using around 80-90Wh in my prototype so far. Main concern is weight. a bit of info is Boosted boards uses less than 100Wh

My requirements are:
top speed: limited to 32km/h and 25km/h for europe and australia
range: 8-10km for throttle only mode in eco mode, 15km+ with assist mode
weight: less than 2.5kg per foot with the boot. so far I'm around 2.2kg. I'm using a VERY light boot.

my last update is this: https://www.facebook.com/ThundrBlade/photos/a.551174475038659.1073741829.433993140090127/561297884026318/?type=3&theater

as you can see in the picture I'm using carbon fiber for the frame to reduce size and weight. Don't think is possible to go any lighter than this so far without taking out batteries or getting an even lighter boot.

btw I've been thinking a lot about going to a hub motor as well. I do believe that a friction drive performs better, but for a consumer product the clean look you get with the hub motor might be worth it. other advantage is that you can fit more batteries inside the frame.

 

[Vanarian]

Your skates are looking cooler and cooler! So you will also adapt 125mm wheels? What model are these?

Careful about carbon fiber frame, for fitness it might be very cool but I fear it might brittle under heavy impacts :wink: But 2.2kg is a big improvement too

I don't know how PETG behaves with bowden drive, though with direct drive at 240°c it is flawless (if I had know this before I'd have started with it, more cost effective than Nylon). It also does react good to smoothening with grit paper!

Depending on what motor you use, yes hub motor is sleek too. Well it is a real headache because you have to fight millimeters EVERYWHERE to get it done right, I can't count how many versions of my hub frame I've done and I'm still redoing it... want it to be flawless, I'd say I'm 80% close to a result which suits my taste enough to be shown.

Best thing is the soulplate, apart from "how the heck do I model this thing???" question, which I solved :lol: :lol: I should be fastening them to my boots by the end of the week

This is tiresome, eveytime I make a step forward on a part, I realize that if I tweak it like that, it'll solve this thing, but then I should apply this form to other parts too, then back to drawing again, then etc, etc... and then suddenly Solidworks won't agree to pierce through this object, so just make it another way, and then etc... WOW.

Come on I'm on it again tonight !

 

[Ryuudan]

This is tiresome, eveytime I make a step forward on a part, I realize that if I tweak it like that, it'll solve this thing, but then I should apply this form to other parts too, then back to drawing again, then etc, etc... and then suddenly Solidworks won't agree to pierce through this object, so just make it another way, and then etc... WOW.

hell yeah thats been my last year designing these.

CF is stronger than steel. The "problem" with it is when it fails, it doesnt bend, it breaks. Aluminum bends, steel depending on how much carbon in the composition also breaks. So, if its strong enough its no problem. Just make it stronger than aluminum and its fine, it will still be lighter. Just calculate (or test) how strong you need it.

In reality though Thundrblade will have aluminum frames in the final version. its just that carbon fiber is easier to prototype.

About the hub motors, I'm thinking better and sticking with the FD for lightness and more torque. Also giving up now on the FD and turning to hub motors is kind of a waste of time. I need to put these out this year. When hub motors are more developed and ESCs get cheaper I will make a 4WD with all hub motors very similar to ATs, but its in the future.

But I have a question about your hub motors. How are you supporting it? you can fix one side of the motor can in normal 608 bearings, but you would need another point of support otherwise the can would bend with jumps. It can somewhat withstand skaters because most of them are using longboards, but how are you gonna solve this? I guessed your are using 8mm axles and fixing one side of the moto

 

[Vanarian]

When hub motors are more developed and ESCs get cheaper I will make a 4WD with all hub motors very similar to ATs, but its in the future.

But I have a question about your hub motors. How are you supporting it? you can fix one side of the motor can in normal 608 bearings, but you would need another point of support otherwise the can would bend with jumps. It can somewhat withstand skaters because most of them are using longboards, but how are you gonna solve this? I guessed your are using 8mm axles and fixing one side of the moto

I totally understand you, I want my skates out ASAP this year too (though there is still lot of work before reaching this goal ).

Well I already have a mature hub motor mount type (where the rest is still like v0.5-0.8, hub mount would be like v1.0) and motor source too, I might be able to provide them for you later

The can cannot bend in my hubs unless the whole frame itself were to bend or break (so too much impact for the whole skates and rider either way) because the wheel doesn't sit at all on the can. Also there are support and tightening on both sides of the wheel, this was the first challenge I solved

How do you make your CF parts?

 

[Ryuudan]

oh, please show me some schematics, even hand drawn would do, but since you 3D printed yours, a screenshot would do. just for me to understand it.

anyway I will try to guess it.
since you are saying you have 2 supports, you either put the wheel all around the motor or you put the wheel to the side of the motor in a way that the wheel structure gets the impact.
to make the wheel around the motor you would need to glue/fix the stator of the motor to the 8mm axle. Then build the wheel core around the can and fixing it to the can by means of the propeller screws.
to make the wheel to the side you could fix the stator to the frame and build the wheel core halfway over the can which is somewhat a very ugly design. (which I might try)

so I will guess you are building the around the motor and not putting any weight on the can. So, how did you fix the stator to the axle? You could make and adapter and screw it across the axle. You could make a cut on the axle to look like a shaft like a chanfer a straight cut so the stator wouldnt spin.

the main problem with this around the motor design I see is how do you manage the wires.

about the carbon fiber. its really easy to make your own carbon fiber, but its troublesome and makes a mess. its the same way they make glass fiber. you get the fiber, embed them in resin and put over your mold. wait 1 or 2 days to cure, sand it and cut it, then you get a clear resin over it to get a shiny look. BUT I didn't do this because its troublesome and I live in a very small apartment. What I did was buy the carbon fiber sheet done from ali express and cut it with a dremel tool.

My frame uses the simplest design possible for a inline skate frame. you have 2 sheets and they screw to the boot by means of an adapter which is 3D printed. I'm testing right now a 2mm thick carbon fiber sheet, but its too flexible
btw most of bicycle parts made out of carbon fiber are handmade with little to no machinery involved. I don't think thundrblade will have a so high demand I couldnt handmade most of the frames. Anyway a desktop CNC Mill would do a great job of cutting carbon fiber since its really really easy to sand it.

 

[Vanarian]

Sorry I got to clean my online stuff, encountered some problems with my deviantart account so I will be re-uploading pictures ASAP. Could not go test my parts this weekend as it was HORRIBLE and I just got hooked on work since Monday.

Please be patient as better pictures will be posted back soon enough Even my previous post was messy. Whatever, to try to explain for you again (I found my words confusing, sorry again - have I ever posted so many "sorry" in one post? ) the concept around my hubs is that I'm kinda artificially forcing the wheel to sit on the motor shaft and on frame part. Unless the shaft and the frame were to bend or broke, nothing can happen to the motor or the can as it is only used to rotate everything, not support it.

To me it is clearer but is it again confusing? I went through really tiresome days

Also, thank you for the tip about CNC carbon fiber. When you can, you should really try PETG if bowden extruder allow it on your next printer. It is a fantastic material, I hammered and snaped my parts, threw them through the living room and they are still as fresh as out from the printing bed. No cracks, no noises, ultra rigid design. I love it.

EDIT : ok went back and forth though the topic and good news is the forum still has my previous pictures hosted here

 

[Hummina Shadeeba]

First half rim printed.... AND FAILED I am almost there, it fits nicely around the motor but some dimensions are really wrong. Back to drawing.

Hi vanarian. I read your last post asking about carbon fiber and am looking through the thread trying to find your design. I remember you sent it to me long ago but I couldn't visualize it. I like your challenge and am glad to see you're still on it.

Anyway carbon fiber construction might be ideal for you but not doing a laminate construction but instead use your 3D printed part to make a silicone mold you can fill with resin and carbon fiber and vacuum or pressure pot it. You can get strong detailed parts this way and it's not messy. You might have to machine them later or not. You could even add metal inserts into the castings maybe. I have no idea as don't know how you're planning to do it.

In the design if it's going to last the shafts and housings for bearings need to be interference fits (shrink or press) because of the loads otherwise the shaft and housing will deteriorate (but u can sneak by with a tight slide fit and retaining fluid) but also there needs to be clearance for thermal expansion within the bearing if it's going to last and bearings with a "c" rating allows this and are intended for just such an environment. But I don't understand your design and you might not be trying to have bearings support both the loads and keeping the rotor and stator positioned in relation to each other

This part here I wonder where it goes. If that's a bearing seat and also sitting right beside the motor your maybe asking too much of the material.

 

[rmrf]

Where did you order PETG?

 

[Vanarian]

rmrf Search for eSun PETG, I order it directly in France, 1kg spool but they mustbe available everywhere. Quality PETG (nothing to envy to Taulman T-Glase as example) for cheap price.

Hummina Thank you for your support! Well I think about 7075 alu or injection mold part, both should be enough to protect the motor.

The rim shown in picture should go further down the shaft, it couldn't due to wrong sizes reasons stopping me to tighten it. The shaft is stopped by an inter-bearing part (don't know the name), it sticks to the smaller ring of the 608 bearing shown in picture but grip wax is also a good idea to prevent any axial movements when carving, thank you for that

Thing is like a 3 bearings system, both different size and form and all are stuck in place and wheel load is applied through all 3 :wink: kinda like expanding the shaft diameter artificially around the motor.

EDIT : Don't know how but you just made me realize that I can do without my inter bearing part and I'd gain a lot of strength and shave weight by doing so! Why the heck didn't I think about it sooner, I'm stupid Hey we should talk more often about hubs Thanks again for the inspiration!

 

[Ryuudan]

Hey, how's your build going?

I have finally working VESCs in my build using FOC.

here's a video to show it working and how silent it has become.

https://youtu.be/kw0315SISdA
for some reason I cannot embed youtube videos here on the forum.
[youtube]https://www.youtube.com/watch?v=kw0315SISdA[/youtube]

Anyway, FOC is mind blowing. I still have to tweak around the settings to unleash my motors power, but even then it already goes from stop and the smoothness and the silence I'm in awe.

 

[sk8norcal]

^you only need to put "kw0315SISdA" between the tags.
[youtube]kw0315SISdA[/youtube]

 

[Ryuudan]

^you only need to put "kw0315SISdA" between the tags.

thank you sir. I learned something today.

 

[Vanarian]

Awesome work! BTW the silence of your inlines with 125MM Fothon wheels is really nice. You've updated your boots too Xsjado 2.0 right? Find it beautiful.

How does it compare to your previous ESC? I was sure VESC would make you love it

I'm on my way too, I'll try to bring all updates soon!

 

[Vanarian]

Ok here are two quick pictures, I'm ashamed to STILL encounter some millimeters problems after having rounded my parts at least a hundred time. Well, some were solved with the hammer for the time being Slow progress, but progress for sure ! There are lot of other parts that I haven't printed to try them yet. Also got another spool of PETG.

Here are the previews!

I kinda like the hub style a lot, what about you?

EDIT : Almost forgot! New improvement made with battery packs integration for the DIY without going thicker : 12S 5.2Ah x2, which gives a range of 262Wh x2 = 524Wh total! Who said that inline skates were bound to get less range than e-boards?

Also I figured a solution to legally flight with 200Wh of batteries with these inlines without fearing the air US regulations!

 

[saul]

thats the same size pack on my board!

I can't see where you found all this space! crazy but awesome. 8)

 

[Vanarian]

Thanks :wink: the secret is the base plate! I want to show it soon but still have difficulties in modeling it, complex surface design to make it appear thinner than it is (aerodynamic is important too IMO). Previous version was ugly but sleek aero :lol: