My BL Savage

I think I'm going to first go with a standard slipperential with a revo slipper, this will allow me to put the motor in a good distance above the driveline. It will also allow me to use a somewhat crazy idea to adjust the gear mesh (not having to move the motor to adjust it). I wish I could explain it with words, but I'll have to draw it to explain. On to Solidworks tutorials!

Just doing some gearing calculations, and I was wondering what I should aim for to be the final reduction ratio with my setup?

[lincpimp]

Not sure, what motor, batterys, etc are you planning on using. I usually aim for around 35k rpm motor speed, and 40mph vehicle speed. You are going to use the revo spur gears, correct? So you have 36, 38, 40t spurs and pinions from 25t down to whatever will fit without having part of the gear reduction assembly contacting with the motor.

I'm using an LMT 2240 14t (1057 KV) on either 8s or 10s lipo, 40 series Moabs. Using BrianG's calc I can get anywhere from 10:1 to 20:1 fairly easily, but is there a way to calculate the optimum ratio for my truck?

[lincpimp]

Somewhere between 15:1 and 17:1 looks good. That would be pinion/spur of 18/40 (primary) and secondary of 20/46 for 10s lipo. For 8s lipo you could do 20/40 primary ratio

Alright thanks! I think I have a good pinion selection for the 14:1-17:1 range if I go with a Revo-style slipperential, which is probably going to be my route.

I now have another question (which is somewhat unrelated), but does anyone know if Brushless setups have regenerative braking like Hybrid cars do? Reason I'm wondering is because I'm thinking of using mechanical brakes for the bias (and to have less strain on the motor/esc), but if there would be a noticable decrease in runtime, I'd veto it. I'm assuming that regenerative braking hs something to do with mechnical brkes on a hybrid car, and wouldn't be applied to this scale of a system, but just wondering.

Also, how many amps does a normal radio setup pull? By "normal" I mean dual steering servos and a reciever. And if I use an external BEC, wouldn't it put a bit more strain on the batteries than if I used a seperate reciever pack? (might seem random, I know, but I just want to know if I should get an external BEC or not, rather use a reciever pack if there is a difference).

[lincpimp]

They do have a form of regerative braking. I would say that you may have issues finding a car esc that can handle 10s lipo? Do you have one in mind?

You may have issues fitting the brake disk on the end of the slipperential assemble that the slipper and spur is on. You may have to put that disk on the diff case.

I would suggest a castle creations bec. Very light, and small, and adjustable with the castle link, plus it has plenty of power to run a pair of servos (or 10 if you want). It works alot better than a rx pack, as the voltage is rock solid all of the time. Plus you never need to charge it!

Originally Posted by lincpimp

They do have a form of regerative braking. I would say that you may have issues finding a car esc that can handle 10s lipo? Do you have one in mind?

I already have the Brushless system. The ESC I have that I'm going to use is a BK 36120 Car. It was top of the line when I got it 2 years ago!

Originally Posted by lincpimp

You may have issues fitting the brake disk on the end of the slipperential assemble that the slipper and spur is on. You may have to put that disk on the diff case.

This is true, I'm sure I'll find someway to make it fit though.

Originally Posted by lincpimp

I would suggest a castle creations bec. Very light, and small, and adjustable with the castle link, plus it has plenty of power to run a pair of servos (or 10 if you want). It works alot better than a rx pack, as the voltage is rock solid all of the time. Plus you never need to charge it!

Alright, I'm sold! I'll pick one (or two) up on my next trip to my LHS. Hopefully they'll have em. If not I'll get em from Mike!

[Patrick]

The castle bec has a maximum input voltage of 26v, so if your going to use more than 6s I'd look for a different one.
The UBEC Mikes sells can take 40v, so I don't know if 10s right off the charger will be too much. http://www.rc-monster.com/proddetail...=6vubec&cat=21 Out of stock of course.
I think dimension engineering makes some even higher voltage ones, but I've never looked into them.

Ah, thanks for the heads up. I'll still pick up one for my CRT though.

So it looks like I'm going to get a miniature mill next month. I'm now planning on doing all/most of the drawing in Solidworks, then printing out templates for me to mill the pieces manually. If I was going the CNC route like I originally intended, I'd spend a comparable amount of money for a one time deal, so I think that this is the better choice. Sure the CNC parts would look nicer, but getting a mill would allow me to expand on the design/repair/change the design(s) without costing me a fortune.
I have a question though.. does anyone know which parts are used in the Slipperential that Mike used to sell for the G3 Revo. I see it has the revo slipper, then an idler gear of sorts? If anyone knows, it'd be helpful.

Thanks!

[lincpimp]

I am going to guess, that unless he made his own slipper shaft, it is a revo input shaft, al of the revo slipper components, a 20t pinion that is affixed to the shaft somehow.

My revo uses the input shaft, I ground a flat area on the shaft, where I wanted the pinion to stay. I then used an al tube to keep the shaft centered between the bearings. It just fits between the pinion and the rear bearing.

[suicideneil]

This might prove useful possibly.

Originally Posted by suicideneil

This might prove useful possibly.

That is very helpful, thank you!

My birthday is tommorow (or today by forum time, I think, ) and I think I am going to have enough money from presents and such to get a miniature mill so I can get started on finishing this thing. I haven't been learning as much Solidworks as I'd like to, but I've been really busy this month. I am going to have a lot more time next month, and can really start bearing down on this project to get it running!

[lutach]

I'll be watching this thread.