Another Electric Onda Board..

This time a Longa.. I've lurked for a long time and the time's now ripe to start my longboard project. So far it looks like..

NTM 50mm 2400w motor
6s banks of recycled 18650s (very low usage) in a 6s4p configuration (LGDAHB21865, 1500mah, free so I can't complain)
http://www.thingiverse.com/thing:820139

14t gear on the motor side
42t gear on the wheel side
http://www.thingiverse.com/thing:820097


The mount is a work in progress, I just got it mocked up today.



The idea is to mount everything, get it aligned properly, then use the two screwholes on the mount to pilot a couple holes into the trucks, say, a couple millimeters deep each. I'll tap them for M4 screws, and I'm hoping this will hold even when 3d printed.

The print in my mockup is ABS at 20% infill. I'm very comfortable printing in Taulman 618 (nylon) and will print the finished piece in that. I was hoping to get a little feedback on the mount before I go full bore. I plan on gusseting it up a bit to stop any lateral shear, but I tested it out a bit today:

[youtube]NCSKjRI6MFo[/youtube]

So far I'm satisfied and I hope to complete the project this weekend. Anyone have any feedback on the mount system? I'm not a school-taught engineer so any feedback is appreciated.

That's sweet.

Where do you plan to put your ESC and batteries?

On top?

I am thinking of taking alum sheet and attach to truck bolts on top and using the sheet to velcro/strap down my ESC and batteries.

I want to keep the top of the deck as clean as possible, so I'll find somewhere on the underside to mount the ESC and ubec and balance plugs and whatnot. I haven't settled on placement yet, but once I do I'll draw up an ESC mount 'lowrizzle' style and add it to thingiverse so anyone else that wants to can use it.

hey, welcome! that board is niiice!
may I ask what is the bolt circle diameter at the Wheel sprocket ?

I used M5s at the wheel sprocket holes, I landed on 38mm from center of wheel to center of hole in the sprocket. It's off by a bit but it self-taps into the wheel to be close enough, I hope.

Looks great! I hope to have my Onda up and running soon too.

The gear reduction of 14 to 42 seams a bit small for those big wheels. May bee a bit uneffective.

If 1:3 doesn't work out with the wheel size, I have the printer to reiterate until I get it right. I already have a 20t motor and 40t wheel gear printed just in case.

Did a dry run test today, first firing so far:

[youtube]B9rNlwnUkkY[/youtube]

I'm also thinking about how to handle the keyway thing. I'm of the mind that I'd rather shear plastic than have other stuff break, so after I grind in the channel, I think I'll use a printed 100% infill ABS keyway instead of using a metal one. I'm thinking safety in the way that I'd rather my clutch start to fail before the motor or transmission fails in a car. Hope it works, so far everything's come together surprisingly well.

And just like that it's dead =)

I drilled in my keyway slot, got everything setup then let the magic smoke out of my ESC. I think (I'm not sure) that two of the motor's wires may have arced since their shrink tube was a bit ratty. I took the ESC apart and one of the caps had literally blown out of it's socket. I ordered a new pair off HobbyKing and another motor (just in case).

[youtube]iHR_xrSkE2k[/youtube]

A bit of an update - I ended up mounting stuff on top even though I kinda wanted it on the bottom. For now I sketched up a little ESC/switch/TX mount and a battery mount that fits through the truck holes.



Both aren't permanent and can be replaced pretty easily. I also ended up re-iterating the mounts so I could run two and crossbar them for an upgrade in rigidity. Now I want to pick up a CNC router to make it all in aluminum next.

neat ! looks clean & minimalist. Awesome job on the 3D printed cases

Thanks, I wanted to get all the gear under the board so it wouldn't look so 'directional' but there's no way to make it stealthy either way, so I'll deal with it. I'll probably test out getting the electronics under the board AFTER the long weekend of riding

well, I think it looks great like this, it allows you to enjoy the flex of the deck. You need to get rid of this GT2B case and that would be perfect!

I think I screwed up again. The Hobbyking 120a ESC is rated '5-10 cells Ni-xx (NiMH / NiCd) 2-4 cells Li-Po' but I'm running it 6s lipo. It hasn't overheated yet so I'll probably just run it until it dies. I need to read more carefully in the future, though.

Sweet job on the 3d enclosures!

Thanks, I just put about 5 miles on them and found the battery tray likes to break off right where I velcro the battery in, so instead I'm just wrapping velcro around the whole deal and not using the slots. The unfortunate nature of 3d printing is that if I wanted it stronger vertically I'd have to print it that way which would mean a really tall print a murderous amounts of support structure to print/remove. I think in the next month or so I'll either pick up a 3040 cnc router or make one then redo all of this in aluminum.

I also switched to FWD and it feels way more natural. After the 5 mile ride (I ran out one of the big 5000mah 6s packs) the motor was pretty warm but the ESC seemed fine.

lowrizzle said:

If 1:3 doesn't work out with the wheel size, I have the printer to reiterate until I get it right. I already have a 20t motor and 40t wheel gear printed just in case.
..

Click to expand...

20 to 40 (1:2) will be even worse I think that a reduction of 1:4 to 1:6 will fit these wheels best. That shall also put less strain on the motor/ESC keeping the temp down. But a high gear reduction can be a problem with belt slippage.

Barndom said:

lowrizzle said:

If 1:3 doesn't work out with the wheel size, I have the printer to reiterate until I get it right. I already have a 20t motor and 40t wheel gear printed just in case.
..

Click to expand...

20 to 40 (1:2) will be even worse I think that a reduction of 1:4 to 1:6 will fit these wheels best. That shall also put less strain on the motor/ESC keeping the temp down. But a high gear reduction can be a problem with belt slippage.

Click to expand...

Good point. I'll need to do some math to figure out how long of a belt to test out, but I do want to try a few different ratios until I find the one that's right.

A coworker finished up a CNC mill project so it looks like I can get the mounts made pretty soon without having to make my own machine. The PET+ sprocket seems to be holding up really nicely, and I printed a few extras, so I think all I need are proper mounts.

lowrizzle said:

The Hobbyking 120a ESC is rated '5-10 cells Ni-xx (NiMH / NiCd) 2-4 cells Li-Po' but I'm running it 6s lipo. It hasn't overheated yet so I'll probably just run it until it dies.

Click to expand...

Very interresting, please, let us know when it dies

knowing your motor kV would help to find the transmission ratio...

made_in_the_alps_legacy said:

lowrizzle said:

The Hobbyking 120a ESC is rated '5-10 cells Ni-xx (NiMH / NiCd) 2-4 cells Li-Po' but I'm running it 6s lipo. It hasn't overheated yet so I'll probably just run it until it dies.

Click to expand...

Very interresting, please, let us know when it dies

knowing your motor kV would help to find the transmission ratio...

Click to expand...

I've got maybe 12 miles on the 120a ESC so far, the motor is an NTM 5060 270kv.

nice work..very neat..
I did find my onda build was great on battery range due to the large diameter smooth and hard wheels..
I just found the Onda core deck a bit small..but i may make another build with a Longa..
you've inspired me..

In the end, I ended up not running a 3d printed motor mount, I bought some caliber trucks and an enertion mount a year ago and ended up running 14:42 due to lack of belts and mounting options. After putting a few hundred miles on the setup, I got tired of all the gear up top. I wanted to keep the flex in the board, but to get all of the electronics onto the bottom.



I moved from a single 6s battery to two 3s packs in series. I sketched up an enclosure, 3d printed it, then I screwed it to the board with small springs between the board and enclosure. The idea is that with a few millimeters of space gapped on the enclosure, enough to still keep the packs snug, with the spring interface, will let the whole board still flex naturally. It does, or at least seems to.



I also wired up a couple of 12v red LED strips on the 6v bec tap on the 120a ESC I've been using all along. It says right in the documentation for the ESC that its for up to 4s lipos, but I've put about 400 miles on it so far with no ill effects shown. I have another in a box in my board drawer either for another build or to build up to climb hills. The strips light up at the measures 6v (yes not 5v like most BECs) but some of them drop out from time to time, and it's only really noticeable at night. I ran some hot glue on them to make sure they don't peel.

The ESC, RC transponder, and ESC power switch are all held captive in a little enclosure I devised that uses set screws on the side to hold tension just above whatever their upper shoulders are. This way they can't really come unloose on their own. The ESC enclosure is the same 3D printed one I had on top, I just reset holes and woodscrews on the bottom.

I've been riding a lot and drew up and implemented a seriously dumb brake system when I realized I was using my foot against the rear wheel enough to wear down my shoe. The parts all work like I intended, as a shoesaver, mounted through the truck holes through the top. I put grip tape on the insides of the brake shoes, but they went flying on first tap. On second tap at speed, it was a nice brake, but it ate through the plastic quick enough that I took it off. I'll just wear better shoes.



Lastly, I bought some of the 5" Onda wheels and I'm going to build another board, I think. I want to find a nice flexy bamboo board, print some risers, use some caliber trucks, and CNC out some mounts (I bought a machine). My son's been riding a moonshine composite board for over a year and I don't plan on touching it, but something along those lines for these little babies:



They look like candy bars to me. I've had other electric aspirations and so I've had bad packs for a while, today I pulled out 9 useful cells for the next build.

Oh yea, some observations. It goes faster than I want to go already, but cogs on startup without a push and won't climb a hill unless it's at speed. I'm guessing dual motors is the answer to both problems. After 5 miles, the ESC is totally cool but the motor itself is pretty hot. At 10 miles, it's very hot. It seems to spin fine and a lot of motor types are meant to run at speed and high-ish to me temps. Do normal setups have hot motors like this?