Scotts 5th - uh 6th build! now with a video - sorta!

[scottclarke]

Opening post for the benefit of those who asked for more pics in the ebikes gd forum.....

Apologies for the truly horrid chain tensioner - it was a chuck it together and see if it works item after spending many mental hours (2 days!) labouring over how I was going to do it! I'll work it some - give it some curves - it'll not look agricultural for long! The delrin wheel doesn't turn btw - I can turn it by hand as it wears though. It also serves as the guide that keeps the front sprocket where I want it - its an important part!

The sprocket is not held on by anything - it floats on the shaft to the point of lowest tension but is retained at that point by the tensioner/guide.

Quick specs for things without a label or that you can't see!

Outrunner brushless motor 200rpm/v 36V 90A though it'll use over 100 if asked - thats umm - 3.6KW

120A generic brushless esc 150a short term - its ok up to 45V I hear........... time will tell. It says 30 cells on it so should be ok.

Motorcycle throttle/grips.

Custom water bottle containing the linear pot, servo testing device, auxiliary battery, the esc and a fan.

Its currently geared 8:1 - you can work out the theoretical top speed yourselves. One thing I will say though - something I find REALLY cool - at top speed on 24V it doesn't slow down at all up a 10% hill I don't know about 36V because I had a fire during testing!

 

[vanilla ice]

Duuude. I want one.

 

[TylerDurden]

I got confused about the sprocket... it is splined? (but floats horizontally?)

 

[scottclarke]

I got confused about the sprocket... it is splined? (but floats horizontally?)

I have pressed a drawn cup roller clutch - 10mm ID into the sprocket which I machined to 13.85mm to take the roller of 14mm OD.

The sprocket literally floats on the shaft at idle - under load it is of course fixed in position.

Scott

 

[Miles]

Its currently geared 8:1 - you can work out the theoretical top speed yourselves. One thing I will say though - something I find REALLY cool - at top speed on 24V it doesn't slow down at all up a 10% hill I don't know about 36V because I had a fire during testing!

About 40 mph (24V), I guess.

What motor are you using?

 

[TylerDurden]

Ok, I think I got it: the shaft is now essentially part of the clutch which has no inner race....

 

[dirty_d]

yea bout that motor sprocket, do you just have a spacer on the other side to keep it from sliding into the motor and mounting plate, with the E-clip holding it on the other end?

i was thinking of using that motor to make a legal bike, but the Kv is just too high, even at 24V with a 50A limit id need 16:1 gearing to put it at 20mph top speed. that giant 130Kv motor at 24V with a 50A limit would put it at 20mph with an 11.6:1 ratio, with 30 pounds forward force almost all the way up to top speed. the price is 300% more though, maybe there is lower power one with a similar Kv.

 

[scottclarke]

yea bout that motor sprocket, do you just have a spacer on the other side to keep it from sliding into the motor and mounting plate, with the E-clip holding it on the other end?

Nope nothing stops it moving either way. It'll naturally move to the position of straightest chain run - but the tensioner is used to help make sure it never deviates from the .5mm or so clearance the chain currently has from the mounting plate. Maybe I should do a video?

 

[Lenk42602]

Maybe???? Maybe????? DO IT! DO IT!!!!!

I need a cigarette.......


Len

 

[scottclarke]

[What motor are you using?

Miles - see my post in the ebikes gd forum for more answers

 

[Miles]

Thanks. I've just found it

 

[Dee Jay]

chuck it together and see if it works

Cheers to that, scottclark. That's generally how I operate. Lots of imagination and not too much calculations. Not too much talk, until I start to walk.

Damn, I'm starting to rhyme! I maybe the next M&M or Skittles . . . Mentos? :lol:

I just might head this way with my dual motor/20" wheels project instead of Cyclone. Light weight motors, small wheels, low voltage, high AH.. Maybe even a combo geared cyclone for torque at the rear and an outrunner for speed at the front! wheels are definitely turning. . .

J

 

[Link]

Damn, I'm starting to rhyme! I maybe the next M&M or Skittles . . . Mentos? :lol:

You can't have Skittle. I called it first, when I had to write a few lines for English and it got out that I can rap. Not that I do that very often. That is to say, ever.


Anyway, I second the notion of an onboard video of this thing doing 40+.

 

[deecanio]

Hi Scott,

yes more pics and some video would be great!!!
i think more of us will move away from hubs and onto smaller/lighter motors once projects like yours and Matts are complete.

Cheers


D

 

[Ben]

How does the chain hold up at such high RPMs?

You're probably sick of reading this by now, but vids vids vids!!!

 

[Dee Jay]

You can't have Skittle. I called it first, when I had to write a few lines for English and it got out that I can rap.

Oh you mean you work at Pack & Wrap? :lol:

Don't make have to battle you for that name DAWG! I'm The Battle Master! Rick Astley ain't got nothin' on me!

:wink:

J

 

[scottclarke]

How does the chain hold up at such high RPMs?

You're probably sick of reading this by now, but vids vids vids!!!

Chain holds up just fine - these chains and sprockets are used on karts that do 150mph. The 10 tooth pinions are used on karts that do 100mph every day - with motors spinning over 15Krpm.

Vids can't happen on the move - the lens will move and I'll get a black picture

I need to redo the wiring from the esc to the motor - well, I'll check the known weak spots and if any obvious heating effects I'll step up a gauge or 3. Fact is I need to regardless - the phase wires are similar cross section to the main bus wires that melted and set on fire.

 

[dirty_d]

how did you bore out the sprocket, with a boring bar in a boring head on a mill? im thinking about buying one of those Chinese mini-mills like they have on harbor freight. i don't really know much about machining though so id have a lot to learn. it seems like every time i start a project i have to half-ass something because i don't have the tools to machine it properly, for example my e-bikes headtube, i had to use a dremel tool to widen the ID to 1.334" to fit the headset. im curious about the press fit, after you put the roller clutch in the freezer and the sprocket in the oven, how much pressure is actually required to get it in there?

 

[scottclarke]

dirty_d, yeah a boring bar in a lathe. Lack of the right tooling really does make life hard - unless you know a friendly machine shop/jobbing shop. Small engineering places can be very helpful - don't be afraid to ask for a quote!

I used a small vice to press it in - you definately could not do it any other way - it has to either be a fly press or a vice.

 

[scottclarke]

Update on testing.....

The motor is rated at 2800W but is intended for RC vehicle use. As those who do RC flyers know - the motors rating system is a bit of a nonsense - in as much it is rarely a continuous rating - nor a 5 minute or whatever rating - nor is it the max volts X the max current the wire can take!

On this build I opted to use passive radiator cooling by way of heat transfer through the motor plate to a finned heatsink. Other than this - the motor sits behind a whole chunk of ali in the form of the crank, the seatube and elements of the rear swingarm - hardly good for airflow. On a previous build using an AXI I incorporated very effective active cooling that turned out to be essential so going passive seems a retrograde step - and indeed it is.

So, I've incorporated a T type couple into the motor face and have been testing motor heating today to determine what current I must average to keep heating sensible.

The results show this motor has a continuous thermal rating of somewhere around 1800W when a 45C rise is chosen. You could of course run hotter - but if your ambient is 30C your looking at 75C motor temp - a little high for my liking. Here it rarely gets above 25C so I am looking at 65-70C most of the time. If this was mounted in a plane with good venting I guess it probably would run 2800W with a similar rise.

At 2800W+ it heats up fast - seeing a rise of 80C in less than 1 minute of loading. I don't know the numbers for this though since my meter only goes to 100A - suffice to say it was more than 100A.

I am not going to look at active cooling based on these results. The bike will live most of its life doing a 13 mile journey with a total of 1 - possibly 3 stops so cooling due to airflow (40mph) will be available almost all the time.

At 2 points I have 5-7% hills likely to exceed 1 minute in length. Not a biggie to slow down a bit but I may not need to - I'll do the journey once with the meter on and see how hot it gets.

Bear in mind this is only applicable to this build - motor heating is entirely dependant on available cooling and here - it is bad!

Still, don't buy one of these thinking you can run at 2.8KW all day - it ain't gonna happen!

Scott

 

[dirty_d]

thats why im going with the 130Kv monster 8)

 

[recumpence]

I have you in my sights. My eye is on you!

Enjoying the build. I am looking forward to more testing.

Matt

Oh, run the motor wires as short as possible. That helps with these motors and ESCs.

 

[deecanio]

im a little lost here scott, does the gearing from the motor to the rear sprocket negate the need for a stepdown box like matts? doesn't it mean that the motor takes the full load from the wheel meaning it will get rather hot under load?
i wish i had more brain
it would seem that these RC motors are way cool for use with ebikes but how best to set them up?
I take it that because the rpm is so high there's no way to run one through the gears like the cyclone setups, would this be possible using a bigger sprocket on the motor?
Anyway more pics and some video please - if your cam wont take the abuse on the bike just leave it on a wall or something and do some drive by's???
watching yours and matts build with massive interest!!!!!


Cheers


D

 

[Link]

You can't have Skittle. I called it first, when I had to write a few lines for English and it got out that I can rap.

Oh you mean you work at Pack & Wrap? :lol:

Don't make have to battle you for that name DAWG! I'm The Battle Master! Rick Astley ain't got nothin' on me!

:wink:

J

Rick Astley doesn't have much on anybody, to my knowledge.

And a distant relationship to the actual Eminem gets me dibs.


Also: Vids...I still don't see them...

 

[Dee Jay]

And a distant relationship to the actual Eminem gets me dibs.

Dude, get out of my mind . . . .

them's battling words.

You might be Eminem's distant-cousin's-friend's-girlfriend's-acquaintance BUT . . . I was touched by greatness. YEAH, I ran up to "Easy E" of NWA fame in LA (before he died of AIDS) to give him my demo tape and he gave me a good swift kick to the curb and I have scars to prove it! How's that for street creds, homey? What do you got, Eminem's autograph? :lol:

All kidding aside: scottclarke, I'm glad I caught your updated photos. Very interesting, thanks! And very nice miniature vase. i bet it's where you keep your weed! Anyway, yeah Vids Vids Vids!

All this rap hoopla reminds me that I have some rap in one of my old mixes which is rare cuz I'm not too much into rap, but check it out!

http://endless-sphere.com/forums/viewtopic.php?f=1&t=2997&p=71003#p71003

One of fechter's electronica track will be featured in my NEW mix by this Friday, *this I promise*!


J