RC Drive Recumbent Trike Build

[marka-ee]

Very interesting. I also have a trike I'd like to improve its performance of. It's a 20 inch wheels all around type. I'm considering one of the Vevor/Kunray motor kits. I was thinking a single stage belt reduction with a custom sprocket almost the same size as the rim in the back. Are you using nylon gears in your first stage to try to limit the "dentist drill" sound that these sometimes make?

 

[Squilt]

The drivetrain fits. Had to re-print a bunch of one part to get the chain tension right but it doesn't need any other changes as far as I can tell. Threw some 3d printed gears in there as well to play around with. Video

Next step would be buying and machining parts. But I first want to have the final image in my head of where everything will go. So now that the drivetrain has been taken care of, next is the battery. I 3d printed 28 of the Headway 38120 cells I'll be using and now im sticking them together in various configurations with tape and placing them around the trike to try and figure out placement. The ideal area would be up front and low to the ground to help with cornering, but with the moving pedals and turning wheels there just isn't enough space there. I'm thinking about placing them just under the seat on both sides.

I'm well aware of the lacking energy density of these cells, this pack will only be 750wh. But I'm choosing these cells because of their power density. On top of the fact that dealing with 28 cells is a lot easier than dealing with hundreds of 18650s. And LFP cells can handle more abuse and still last longer than LCO cells.

 

[The Toecutter]

If you put an aerodynamically slippery body over this thing, 750 Wh will go for a surprisingly-long distance at speed.

My first build only needed 8 Wh/mile or so to hold 30-35 mph on flat ground, accelerating with 250W and once at speed, my pedaling accounting for about 1/3 the motive force. More power for acceleration does eat into efficiency though.

 

[ccihon]

Looking good. I have an older, hard-tail version of this Performer trike. Be cautious in placing large amount of mass forward of the front wheels. This can lead to steering instability. I would also recommend a hydraulic steering damper if this thing is as fast as it might be.

 

[Squilt]

Looking good. I have an older, hard-tail version of this Performer trike. Be cautious in placing large amount of mass forward of the front wheels. This can lead to steering instability. I would also recommend a hydraulic steering damper if this thing is as fast as it might be.

I took this thing to about 40mph downhill before the wheel swap, and it feels much better with the heavier wheels. But adding a damper should be easy enough if I need one.

 

[Squilt]

I lied, the drivetrain was not taken care of. The motor drive side is fine, it's just that now the motor gets in the way of the bike chain. I thought I could bring the chain under the swingarm pivot but there's no way it wouldn't rub against the side of the swingarm that way, and I would have needed a bigger idler where the existing one is. So what I came up with was adding another idler that moves the chain above the motor.

Issues are that the sideways chain angle between the cassette and the new idler is now greater than it was between the cassette and the stock idler. This affects shifting and increases friction. It can still run through all the gears without jumping. Shifting performance under load is TBD. However I'm not too concerned about changes that negatively impact the pedal drive because with the powertrain I'm putting in, pedaling should only be necessary as a backup. I'm also going to need to lengthen the chain since the path is a bit longer now.

It's clamping onto the bracket holding the swingarm pivot. That area seems pretty strong, and when I make these parts out of aluminum they should be more than strong enough to take the forces pushing the idler down when pedaling. It already isn't deflecting much with the 3D-printed parts that are on now.

I'll add a wear pad or something to the motor mount so that over bumps, the chain doesn't slap and stick to the very expensive Astro motor.

Now onto the battery.

 

[marka-ee]

I'm just curious how much filament you went through so far on this project.

 

[DaLanMan]

Pfft, I have been doing fabrication as a side hustle for a long long while. I think it is hilarious wondering about filament. I would have bought this stuff by the truckload. beats the crud out of having to get the CNC up for every change and wait between an hour and a week for the part to come back out.

I love the utility of 3d printing. There is a huge marketplace for 3d print farms not sure why people are not glomming on.

 

[Squilt]

I'm just curious how much filament you went through so far on this project.

At least 1kg in the last month

Pfft, I have been doing fabrication as a side hustle for a long long while. I think it is hilarious wondering about filament. I would have bought this stuff by the truckload. beats the crud out of having to get the CNC up for every change and wait between an hour and a week for the part to come back out.

I love the utility of 3d printing. There is a huge marketplace for 3d print farms not sure why people are not glomming on.

Prototyping has never been more rapid and cheap. I can afford to print several test fits without even measuring properly. Unthinkable on the mill.

 

[marka-ee]

Yeah, I've been 3D printing for more than seven years now. My next 3D printing project will be CADing up and printing the 20 inch toothed belt pulley for the back wheel of my trike. It's going to attach to the side of the rim. Modeling the stress on this is very complicated so I'm just going to guess I think.

 

[DaLanMan]

Trick I learned while running a company full of smart people... Look at what they do with the irritating portion of grunt work ::looks all happy with himself:: Get an intern and make themn do it. Ob a more serious note, you can hiut up engineering students and offer them some cash and ROP time (school can help with that) If you don't have a degree in the same general ballpark often they can get a prof to join in to lend a credential (and get a publishing credit) and it is *not* taking advantage. In the engineering world your degree is a "oh that's nice" item, then you are asked what you have actually done, that always has a *LOT* more weight given to it.

Besides, that is not something you can easily do with a 3d printer, that is better suited to MatLab, and even renting access to the software was hundreds of dollars a month. Actually getting to install your own server..... that starts at last I looked 3500 + license per user in multi-user realms and that usually was only discounted if you were splitting it up between dozens of projects.No clue how to get cheap matlab work done, most students and wize folks steer away lest they bore you with thier talkings...

 

[marka-ee]

If you're referring to my question about modeling the stress on this type of pulley, I think it's a very difficult problem for any level of engineer. The problem is that the loads on the teeth are one level of complexity, but then the side-mounted nature of the pulley, and then the fact that it's 3D printed with something with a non-homogeneous type grain structure with variable amounts of strength in different directions adds yet another level of complexity. I have access to SOLIDWORKS and its stress analysis is only primitive for this type of application, unfortunately.

 

[DaLanMan]

Brother, you have obviously never met a moddling nerd...

Nerds come in all shapes sizes and flavors, from workout gear to I kid you not Egg carving. One of the oddest of nerds is the Moddling nerd, they fantasize about incredibly complex things that they will only do in their spare time because ain't no one gonna pay you for the weird thing you are thinking about.

I heard one of the guys who was a MatLab specialist proudly announce that he had done it! He had modeled the toaster that had a weird hotspot...

Ok, still not as weird as people with Gold Fever. that one still just confuses me.

 

[amberwolf]

One of the oddest of nerds is the Moddling nerd, they fantasize about incredibly complex things that they will only do in their spare time because ain't no one gonna pay you for the weird thing you are thinking about.

That would be me, though my wierd things are so numerous and in more categories of technology and knowledge than I have the ability and time to list....

 

[Squilt]

Weirdness has always been a primary motivation behind my projects

 

[Squilt]

Bought a 15t cog from a 9 speed cassette on eBay and got to work making the aluminum parts and testing it out. Because the idler moves the chain up, the suspension is compressed by pedaling. It's not great but I don't see any way around it. Still moves around just fine. It shifts through all the gears as well as it did before, besides some infrequent jumping in the tallest gear. I'm almost disappointed that it shifted okay. I had a cool idea for a mechanism to use the movement of the shift cable to move the idler side to side on its shaft to keep the chain line straight. Guess I'll put a pin in that for now.




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