First size test for the bike wheel hub battery I'm designing - which I'm going to tongue in cheek refer to as the Tri-Force due to its three pieces - is a success. There's enough clearance between the spokes to get the pieces in and out.
The plan is to attach them with straps so I can maneuver them, then secure them at the hinges. Depending on the angles I may be able to skip the hinges.
[#]bikeTooter #3dprinting #diy
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I'm enjoying the challenges of designing for the "Tri-Force" bike wheel hub battery.
Since the lights will be remote controlled, I need to fit a receiver into the plug; I don't want in the battery because that may complicate charging.
So, I have to fit a 11x24x8mm chip, and the eight wires involved (two from the battery, two from the lights, four from the chip) all into as small a form factor as possible, all in the space between two spokes forming a wedge.
Fun!
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After five and a half hours, the first full scale test is ready. And there are notes.
To accommodate using battery clips instead of a modeled holder and a nickel strip tail, I had to increase the thickness to 36mm. Now it barely fits between the spokes.
But, I was able to get in on and off with two of the three hinge pins in, which is good.
When the clips arrive on Tuesday I'll iterate on the thickness - I may have to use 21700 cells instead of 26650 cells.
[#]bikeTooter #3dprinting #diy
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The mark II Tri-Force bike wheel hub battery fits perfectly. The extra 4mm of clearance makes it easy to install with two of the three hinge pins in; although it helps to have three hands.
This means I have to go with 21700 cells instead of 26550 cells, which is fine. I think i need to recheck the outer diameter of the hub - 32mm is feeling a little snug.
Fortunately I already have a hinged ring designed for the handlebar mount, so I can reuse that.
[#]biketooter #3dprinting #diy
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The really cool thing about the lights I'm going to power with the wheel hub battery is they're remote controlled via a switch on the handlebars, rather than having to reach in between the spokes to turn them on/off.
I am not an electrical engineer but I feel it's probably a bad idea to have electrical components dangling freely in your wheels.
So I've designed a piece to go around the wires for the LEDs to house the receiver and the many wires involved.
[#]biketooter #3dprinting #diy
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A challenge in #3dprinting a bike wheel hub battery and controller will be the transmitter. I opted for an A23 battery for its voltage and form factor. Fortunately you can buy tiny little battery clamps to secure it.
Unfortuately there's exactly zero clearance between the battery and the base plate when installed, so I'm unsure how I'm going to make this work. I can't print in place because they'll interfere with the tool head.
I'm thinking a very small clip?
[#]biketooter #diy #electronics
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It's print day today for the bike wheel hub battery. I went through most of a spool of PLA iterating on designs, and now I can print the "final" parts.
I'm a little disappointed that I ended up having to have multiple shell variations - I could get away with just two if I had metric drill bits.
Oh well. I didn't design this for mass production.
[#]bikeTooter #3dprinting #diy
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A weekend of printing later and all the parts for the bike wheel hub battery - aka the "Tri-Force" - are ready.
The battery clips have pins that fit into slots and are glued in place. Everything else will be held together by nuts and bolts - a grand total of:
Too many fasteners? Not for an #ebike part!
[#]biketooter #3dprinting #diy
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"Ryan, you don't have to design everything to be a two identical parts with rotational symmetry."
"BLASPHEMY!"
It's an assembly jig for the battery case - to hold the halves of the three shells in situ while I do the wiring.
Why two parts? Because one continuous piece wouldn't fit on my print bed.
[#]bikeTooter #3dprinting #diy
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Let there be light!
I'm a little concerned that I seem to have fried the BMS on my test battery during this test - hence the pack of AAs. It did fine for the bench test a few weeks ago...
Oh well. The transmitter ia wired, and so is one of the receivers. I'll wire the other one tomorrow and see if I can pair it with the same transmitter.
Then we'll wire the battery cases, and once I'm sure it all works, then we'll order the LED strips.
[#]biketooter #3dprinting #diy #electronics
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I tallied up the cost of building the bike wheel batteries last night.
$70 - and an extra $30 in shipping.
Sure, I could probably get that down if I could get everything in one place, but the full parts list includes forty eight screws, twenty four coupling nuts, twelve battery clips, six battery cells, two battery management system circuits, and two 2.1mm jacks.
I'm sure I might be able to get all of that on Amazon, but there's no telling the quality of it...
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And the battery cells themselves are half of the cost of parts. So there'd be minimal savings from redesigning the part to require fewer - or even no - fasteners or battery clips.
Ultimately, if the design even works, I want to put it out into the world. The parts are easy to acquire. There's not much soldering in the wiring - I taught myself in a weekend.
It's just the cases that a person needs... so I guess I should research print on demand solutions.
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No prototype survives contact with production.
The solder joints must be imperfect, because the light is temperamental and will turn on and off as I move things around to close the shells. The wires are interfering with each other, physically at least. There's too much happening in the main shell.
No worries, I can iterate on the design. I need to give more room for the wires...
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I was able to take it apart and put it back together again. Turning the center wedge 180 degrees (so the battery is "on top" when unfolded) meant for cleaner wire routes.
Tomorrow we'll charge it up, and do a bench test - see how long it can power the 12V LEDs I salvaged from a broken bike tail light.
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That feeling when you have a working prototype.
Half of one, anyway. The LED strips are on order and will arrive later this week. Then I need to decide if I want to adhere the strips to the rims or print dozens of spoke clips to make the lights less permanent.
The weight is good - approximately one pound / half a kilogram. We'll see how it stands up in motion next weekend.
[#]biketooter #3dprinting #diy #electronics
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I tried to get an instant quote from a print-on-demand shop for this and it says about $15 to print, and errored on shipping. Let's say $10. So at least $40 to print a pair of these, plus around $60 in supplies (plus shipping), most of which can't be found at your local hardware store.
I sure am good at designing complicated things...
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The mark I prototype is a successful failure.
Everything worked, for a while. The battery showed a nominal 12V and could power a salvaged e-bike tail light, and later a pair of 5V LED strips wired in series.
But then something went wrong - either the BMS shorted and took a cell with it, or vice versa. I have some (hopefully) better BMS boards on order and will build the mark II when they arrive.
I've also ordered a few options for the lights and will test them head to head.
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The two key metrics are brightness and longevity, with the latter being more important. I'd rather have modest lights that only have to be charged once in a while than overwhelming lights that have to be charged after a few hours of use.
The current contenders are:
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Spending a lazy Saturday iterating on the mark II of the Bike Wheel Hub Battery case.
This iteration requires fewer fasteners and has a more coherent construction history in Fusion 360. It also addresses the issue of the wires pinching between the shells.
[#]biketooter #diy #electronics #3dprinting
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I wonder if anyone has done the work to quantify the bed adhesion of #3dprinting based on total contact area - for both manual removal (a pulling force along the Z+ axis) and programmatic removal (a pushing force along the Y-axis)
Well, I've got nothing better to do today...
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The results are .... interesting.
The model printed at an angle was much easier to remove - too easy, in fact. The supports are better adhered to the bed than they are to the model.
The model printed at an angle has a uniform outer surface. The lower edge has some defects that could be remedied with additional support fins. There may be some droop in the holes and slots but they are still within tolerances.
[#]3dprinting
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Get in, loser, we're doing science.
One of the four options for my bike wheel lights has arrived. At least one other one should arrive today and then we can start doing bench tests and best of all, make a spreadsheet!
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Any good experiment requires a control. The baseline is the Wheel Brightz I currently have - twenty micro LEDs powered by three AAs in a narrow plastic tube.
I measure the lights with a light meter at the center of the wheel, and measure their draw using a multimeter.
Current: 5V / 4.7 mAh
Brightness: ~5 Lux
Vibe: Ok at night, in motion.
Link - https://brightz.com/products/wheel-brightz
Price - $15 / each
[#]bikeTooter
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First challenger is a two meter iNextStation "neon" LED tube.
Size: 12mm x 5mm x 2000mm
Power: 12V / 17 mAh
Brightness: 250 Lux
Vibe: Tron!
Link - https://a.co/d/4819hB9
Price - $10 / each
I'll probably need to 3D print some clips to attach it to the spokes with the optimum orientation. It has a 240° beam angle so it should be visible from both sides of the wheel.
If my math is right, I can get 200-250 hours of illumination on a charge.
[#]bikeTooter
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Second lighting option in order of arrival and ease of testing is a length of LED rope light from Axel Lighting, a "marine and outdoor lighting" company.
This stuff is pricy, and a 27.5" wheel needs a little over seven feet. But it's meant for boats and Portland is wet, so I thought I'd give it a try.
Size - 3/8" x 86"
Power: 12V / 17 mAh
Brightness: 100 Lux
Vibe: Sparkles
Link: https://www.apexlighting.com/boat-lights/led-strips/led-ropelight-perfoot/
Price: $8 / ft
The lights are 1" apart, and will blur together at speed.
[#]bikeTooter
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Pros
Cons
I maybe have to modify the plug, but it's a good option. Visible from all angles, and the spacing means the there will be a dynamic element to the lighting when in motion.
It's out of the question to use if I go down the route of building and selling full kits - a 150' spool is $1,000 and would make 10 sets, so that adds $50 to the materials cost per wheel.
Yeah, no.
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I've got two more options to test - the EL wire is going to need some soldering so may not happen tonight. Next up is a pair of 5V COB LEDs wired in series. I expect it to be bright and thirsty.
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Surprise, surprise. The dual 5V COB LED strips are about the same as the 12V lights.
Size: 5mm x 2000mm
Volts: 8-9V
Power: 11 mAh
Brightness: 30 Lux
Vibe: Sleek
Link: https://www.superlightingled.com/super-slim-4mm-wide-5v-cob-led-strip-320ledsm-p-5707.html
Price: $15 / pair
Pros - lights on both side of the wheel, sharp, preciae appearance.
Cons - fiddly, may not stick well, slightly more complicated wiring.
[#]bikeTooter
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I'll solder the EL wire to the plug tomorrow - and I've ordered an option based on how well the "neon" LEDs act - a three sided diffuser that should give off more light.
And then I have to decide between the options, based on all the metrics I've listed.
I'm leaning towards the neon LEDs; so far they have been the brightest.
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The EL wire was a bust. I don't know if I damaged it while trying to solder it, or if the inverter is bad, but I couldn't get it to light.
Given how fragile the wires are, I don't think it would have survived being in bike wheels for very long.
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So, I have three workable options
The "neon" LED I got is single sided with a 5mmx12mm profile with a 240° beam angle. I've ordered an alternate diffuser that has a 8mm x 8mm profile with a 180° beam angle but a larger glow surface. We'll see which one looks better. The rope light is probably the most durable, but the most expensive.
Next step - build the mark II battery and road test the lights.
[#]bikeTooter
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The second time you do something, it comes out better.
Once it's charged (and a last minute fix to the tolerances on the through mount for the DC jack is printed) I can do a wheel test and finally see the lights in motion.
[#]biketooter #diy #electronics #3dprinting
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There's a lesson to be had here: when designing for a bike wheel, test your mockup against both wheels.
The rear wheel has a lot more stuff in the way.
Edit - turns out the front has issues, too
[#]biketooter #diy #3dprinting
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Using some novel subtractive manufacturing techniques (I drilled a hole in the shell) I was able to connect a 2.1mm DC plug to the battery.
Unfortunately the battery case is not weather safe anymore - I'll need to plug some holes if I want to road test this.
Then I discovered that the "neon" LED tube I bought for testing purposes bends the wrong way to weave between the spokes. So I zip tied it. Maybe not the best solution but it got the job done.
[#]bikeTooter #diy #3dprinting #electronics
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[#]bikeTooter #diy #electronics #3dprinting
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Will you hear that sound while riding?
@yantor3d
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@EverydayMoggie Probably not. That's a combination of the flywheel in the rear hub and possible the connector moving around. The final product will be better secured; this is a proof of concept.
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