Testing the waters with BL

Well, I've done the go fast type BL, but for the first time I'm experimenting with what I guess you could call "go slow" BL.......in a crawler of course. I picked up a KMS 2814/08 outrunner from Hobby People earlier in the week, and finally got to drive it today.

I chose this motor because of the 540 bolt pattern, but the only problem with fitting it was the 4mm shaft, we got around that with some supplies at the store. A friend figured out that 5/32" brass tubing is essentially 3.96mm, close enough to fit the bearings snugly. To use "normal" pinions, I slid some 1/8" stainless steel rod inside the tubing, and later added JB Weld to keep them together as one piece. To hold the shaft in, I made a flat spot for the endbell's set screw, and just used the pinion to hold the other side in (it doesn't bind at all).

After driving it on 3s A123(paired with a Mamba Max esc I had laying around), I'm hooked. Wheel speed is about the same as it was, but low throttle is silky smooth, with tons of torque too. I really like it, but will be sure to beat it up a little just to see how it'll hold up before I fully stand behind it.

You should check out the Crawlmaster motor at holmeshobbies.com. I was running this in my Super and managed to snap a revo driveshaft with this motor. TONS of torque.

Crawlers are cool and very challenging. Who would have thought going slow required so much concentration. You should post a pick of your crawler.

Most recent pics are from today's outing: http://www.rccrawler.com/forum/showthread.php?t=89083 . Mine's the one with the flames, it did okay. I need to widen it, and need to tweak my suspension for easier twisting.

Oh, and I'm not sure if this can be answered here, but my MM esc tends to kinda "lock out" when the truck is going uphill and starts to roll backwards. I've got 50% drag brake set, and that works amazing when facing downhill, but it has a very hard time getting going uphill again if I don't stay on the throttle. Could this be gearing, or a setup with the MM controller somehow? I have it set for low timing hoping it'd be a bit smoother, maybe that did it?

No pressure to reply though, I'm gonna post the same question on RCC where I'm sure there's more experience with outrunners and crawling. Still, any help appreciated. :)

[BrianG]

Could be related to the "Neu/MM syndrome". All the outrunners I know of use slotted stators, which is what the MM has a hard time with. Don't know if this is the case, or if this even matters with outrunners, but try increasing the start power and increasing punch control in the MM software.

Okay, I'll take any help with it right now, so far I'm only half-pleased with it. Amazing torque, and stupid runtime with my A123 pack today (2.5 hrs, still had lots more), but the rolling backwards was a little annoying.

[BrianG]

Well, make your adjustments individually in small steps to find the "just right" setting. Once you get it right (assuming you'll be able to), please post back here with what settings worked.

[ClodMaxx]

yes - please do post back with the settings you end up happy with! i'm building my Stealth up now - the MM is in the mail, and i'll be using 55t brushed motors. i know it's no where near the same, but i have no clue what good settings would be for crawling.

Well, here's what I got from JohnRobHolmes on RC Crawler: "Gear down. You are geared way too high. Put a 13 or 15 on there. Then turn your startup power to high, it wont affect your startup speed. What is your drag brake set to?"

Another guy suggested to put timing to medium, I'll go ahead and do everything suggested so far and see what happens. I might be going out for another run tomorrow at the ultimate crawling grounds Vasquez Rocks, but I have areas around my house that I can still test it out.

I'll be sure to let you guys know how this turns out, I'm anxious for this setup to live up to its full potential too!

[MetalMan]

My crawler does something very similar, where it doesn't like going forward while rolling backwards. It's got that Mamba 25 you sold me, along with a KMS 2826/06 (you shoulda' gotten this one!), and 3s Lipo. To get it to go forward, I've found I have to hit reverse, where it seems the purpose of doing so is to get the Mamba 25 to locate the position of the rotor.

Well, more info from the crawler guys:

raptorman57 - "IMHO,you're running the best ESC for crawling. Like John says to everyone.....Gear down,volt up. Thats how you make the outrunners work smoooooooth. Once you gear down,you'll see the problems go away. If your wheelspeed isn't where you want it,volt up to get it back.

I set all my Mamba's at 100% drag brake.

My start up power is on high.

You can also adjust the throttle and brake curve to fine tune it more to your likings."

JohnRobHolmes - "If you like to let off of the throttle and let it sit on inclines, put more drag brake in. They can get stuck into a downhill rolling mode if the geardown and voltage is too much to overcome."

Those were the most helpful ones, a couple people chimed in with the esc that I "should have got instead"......which doesn't do me any good anyway. I only used this MM esc because I wasn't using it in anything else and knew it'd be up to the abuse.

Travis, why? This one seems to have stupid torque even over geared, but is small enough that it's not hitting the Stealth tranny. Besides, doesn't that one have a 5mm shaft? It wasn't too hard to make the 4mm to 1/8" conversion, but 5mm to 1/8" would be a bit harder.....and I still think it's too big.

[ClodMaxx]

dude, i just now looked at those shots. those are great! looks like someone has a nice DSLR paired with a circular polarizer.

do you have, or have you tried, 4s a123's? esp. concerning the 'volt up to eliminate the problem' comment. i'm curious, as i plan to run 4s2p a123s in mine. i was worried it might be too much, but i also planned to gear down a lot.

[BrianG]

4s A123s should work just fine. The MM works fine with 4s lipos, which has higher voltage.

[MetalMan]

Originally Posted by dabid

Travis, why? This one seems to have stupid torque even over geared, but is small enough that it's not hitting the Stealth tranny. Besides, doesn't that one have a 5mm shaft? It wasn't too hard to make the 4mm to 1/8" conversion, but 5mm to 1/8" would be a bit harder.....and I still think it's too big.

You think the torque of your motor is stupid .

I have access to a machine shop at UCI (University of California, Irvine), where I go to school. Outrunners feature removable shafts, so I simply took the shaft out of the motor, and turned it from 5mm to 1/8". When it still had the 5mm shaft, I was running mod1 gears. Now with the 1/8" shaft, I occasionally have a problem with stripping 32p gears, and would strip out 48p spurs all the time.

[ClodMaxx]

Originally Posted by BrianG

4s A123s should work just fine. The MM works fine with 4s lipos, which has higher voltage.

right on - i'm not worried about the MM specs, as i ran 5s through it without problems...but that was in my heavy maxx. i've never crawled at that high of voltage though. could be fun!!!

Has anyone tried a quark yet? The mambas just dont work that good. A 4s pack is just way overkill for these little trucks, you will just break things. I am going to get a quark and see if it is any better