Custom gearboxs

[Vadim]

I figured this was a good place to ask.
Is there any interest in a high quality gearbox for using rc motors?
I was figuring a 1:10 oil filled gearbox would do for most larger motors.
gears are more efficient then a belt (especially oil bath), and inside a box they would be well protected and fairly quite.
The ratio, and other details would depend on what motor you wanted to mate with it.
The case would probably start as two part ruff cast aluminum, and then machined as necessary.
I've bean wanting to get a nice Sherline mill and lathe, and I need to justify it lol
So, what do you think?

 

[whereswally606]

what do you think the price will be? I have a 80/100 waiting to be put onto a norco savage. This sounds like a great idea.

 

[Vadim]

Well, I'd have to build a prototype first. But maby $250

 

[John in CR]

Well, I'd have to build a prototype first. But maby $250

Reduction only or 2 or 3 speed?

 

[Vadim]

Well, I was thinking reduction only, but they would be made to order, so a multi speed box is possible.

Edit: I could probably manage a sequential gearbox.

 

[Vadim]

Well, a decent small lathe, with the tools needed to make spur gears and machine cases would be about $1750.
Within my budget. I may add a rotary table to that though. The only thing I'd need to buy is bearings.

 

[spinningmagnets]

Thuds 2-speed is about as easy to make as its possible in a garage, also its scalable to be bigger or smaller as desired.
http://endless-sphere.com/forums/viewtopic.php?f=28&t=13731

Another option is taking the shafts and gear-sets from a small Chinese pocketbike, and making a box for it out of heavy square channel on 3 sides, and plate on the rest. E-bike racing will continue to grow, and there is a market for a bullet-proof racing 2-speed...

...and a 3-speed for a cargobike non-hub build (with a cell_man geared 6T at 48V?) is something Yuba Mundo owners would be interested in...
http://endless-sphere.com/forums/viewtopic.php?f=3&t=32220

 

[Vadim]

I do have a preference toward gears vs. chains or timing belts.
They have a slightly higher efficiency, especially if oil bath, a little more reliable, and lighter (though not that significant when compared to the weight of the batteries).

I'll make some cad drawings of a 3 speed gearbox when I get the chance.

 

[neptronix]

Custom gearboxes in oil baths would be super sweet. I think a 10:1 ratio would be perfect for dealing with the smaller, higher speed motors.

I'm not sure if you're going to get the kind of volume you need to actually make money on this though. Might be smart to cater to the gas bike guys first.

 

[Vadim]

I'm buying the lathe for a hobby, making up the cost is a plus.

Mudeling my way through SolidWorks (I grew up on CadKey, totally different).

 

[Vadim]

Well, I got sick of SolidWorks, so I sketched this quick.
This would be a 10:1 box, input and output sides milled from 1/2" aluminum, the rest 1/4" aluminum, with some 10x26x8mm bearings.
Hobby king has a new motor "Turnigy RotoMax 150cc" good for a real 12hp, that size of gear should handle that motor as long as I harden them (not that difficult). You'd put a chain sprocket right on the output.


click to embiggen

Oh, that's 1cm graph paper, to scale, apx. 6" x 2"

 

[neptronix]

Very nice!
If it's something you can just bolt a keyed sprocket onto, then you have something cool.

I'm thinking that this would be good for the scooter MAC/BMC style motors as well.

 

[Vadim]

I'm under the impression that the shaft on most rc motors is removable, if that's so then a new shaft could be made.
For a 9:1 gearbox
A 14mm shaft with a 12tooth mod1 gear machined in the middle would be machined down to whatever the motor needs.
output shaft would start life as a 38mm shaft, machined down to 14mm on aether end for the bearings, then the output would be machined to whatever you wanted, anything 14mm, 1/2" or less, splines added or keyed. The centaur made into a 36tooth gear.
Center gear would be one piece.

 

[nechaus]

Im really wanting to make a small gearbox also.


Id be happy to print of some plastic prototypes, make sure things fit and work well

 

[iamsofunny]

I'll take a piece of that
Are you talking about having different speeds for chain drive? I would gladly spend 250 bucks on such a product

 

[Vadim]

A multi speed gearbox would be more complicated.
But definitely possible. It'd probably be electric shift, it could even me automatic.

 

[nechaus]

When i mean gear box, a two speed would be great
automatic or manual change, but would be awesome to have it automatically

I would be so keen to make a race bike if i got a gear box for my hpm

 

[Vadim]

Well an electronic shifter is probably the easiest anyway, so automatic shifting is easy after that, just a little atmega that cuts motor power for a split second while shifting (no clutch).

I'll sketch up a 2-speed box for that golden motor.
Done work for the summer, and not starting school until the 4th (second year computer engineering) bored stupid lol
I wish I had the lath now.
7/8" shaft correct?

Edit: oh, is the shaft removable on that motor?

 

[nechaus]

Sounds like you could be making your own cnc machine!

 

[Vadim]

Well, I found a good deal on Chinese mini lathe that's already converted, but if I don't get that then I'll do the conversion myself when I get the funds.
A lathe is actually a far more versatile tool then a mill, as you can do a far amount of milling on one.
PM sent.

 

[Vadim]

A bit of quick math wile watching tv.


No-laod 14.3A at 72v
74v
134a max continuous
12mohm
84kv

5780rpm under load
Max power 10kw
95kph top speed
wheel 990rpm
20" wheel

1st 10:1
2nd 5.8:1


Edited for 20" wheel

 

[iamsofunny]

Two speed would be perfect. One easy gear for hills and then one harder one for speed. Manual shifting.
Sounds like quite the project.
What is your schooling?

 

[full-throttle]

Are you aware of these?
http://www.staton-inc.com/store/pro...Gearbox_with_9_16_18_Clutch_Drum-1008-27.html
http://www.staton-inc.com/store/pro...Three_output_shafts_1_2_Mid_Drive-872-27.html

 

[neptronix]

I've got a motor similar to nechaus's .. motenergy 4201 ( etek design ).. has a 7/8 shaft.. but watch out, it can dish out 15kw-20kw peaks, lol. If you design a gearbox for this size motor, you need to think heavy duty motorcycle grade.

 

[Vadim]

I do stress calculations for gear size.
Close to what I'd be building.
Not ideal though, with case hardened 8620 gears one could be made about 1/3 the weight, and the correct gear ratio.