Atomic BB and a case Foot in Mouth

LBRC · Post by **LBRC** » Fri Apr 13, 2007 4:30 am

The Long Story:
One of the locals, lets call him Ricky, couldn’t wait for the Atomic BB motor to show up stateside so he paid EGR the big bucks to ship him one as soon as they came out. Wanting a comm. drop hole in this his latest baby he turned it over to me for the operation since I would unsolder the caps remove the end-bell and use the mini mill instead of the risky rotor drill method. I of course volunteered to perform the surgery because I was anxious to get my hands on one but too cheep to pay Atomic RC’s initial manufacturers suggested retail plus HK shipping.

Anyway when I took the end-bell off for drilling I looked and thought I saw a ball bearing just like this

but now I’m not so sure, hindsight is not always 20/20 and in this case it’s a little blurry, it could have been a case of seeing what I expected and wanted to see, I now wish I’d taken more time and a closer look removing the armature while I was at it, of course Ricky would have had a conniption fit if I had so maybe that would not have been possible, he’s bigger than me.

The problem is that after opening this motor purchased by another local from Atomic Mods up for the same comm. drop hole operation I noticed that it did not.

So now after stating emphatically that they did have ball bearings I have to humbly retract that statement and say that some or possibly even all do not. Am trying to get Ricky to let me open his back up to see if it did/does actually have ball bearings or if I was just hallucinating.

BTW the above Atomic BB with the ball bearing did not come with it installed after taking a close look at the Atomic end-bell I noticed that unlike the stock motor there was a sleeve around the bushing hole as if it was originally poured to take a 4x2mm bearing but for some reason the sleeve and smaller bushing was used instead. After reaming out the sleeve a 4x2mm ball bearing slipped right in just as if it was made to.

One possible explanation could be that since the motor turns at over 50K rpm they had bearing problems, and reliable 4x2mm high speed/temp motor bearing rated at 50,000+ rpm could be a problem in the price range. Just wild speculation but I’m still having trouble imagining why my favorite Mini-Z motor manufacturer would risk their rep by intentionally putting BB on a motor that didn’t have them, and like I said above I’m still not sure that the one I first looked at didn’t actually have them, won’t know until Ricky lets me dissect it and although he’s tentatively agreed I suspect it will take copious amounts of bear for him to actually let me do it. Edit: Rick's motor definitely didn't have ball bearings

so it's either glasses or giving up the libations so just call me four eyes. After seeing the first ball bearing motor on MPM I really didn’t need to open it up for confirmation, but I did anyway.

I don’t mind being wrong, screw up all the time just ask the old lady, but not being absolutely sure one way or the other bites. Am reasonably sure I was sober so if the dam thing doesn’t have at least one bearing in the end-bell then the worms have finally eaten their way to in, sucks.

In the mean time I emailed Atomic RC (not Atomic Mods) hoping for a reasonable explanation.

crazydave · Post by **crazydave** » Fri Apr 13, 2007 7:47 am

I had kinda hoped that motor would have ball bearings, hence the BB name, but I wasn't holding my breath. Considering the size, and price. I just got mine yesterday, and I was like, "Guess they meant it is small and fast like a BB that you shoot from a gun."

That's ok, if it gives me any kind of speed increase, I'll be happy.

ChemicalInDependency · Fri Apr 13, 2007 5:48 pm

wow thats kinda a bummer, I may hold off on ordering one now. I was pretty skeptical about it really being a ball bearing because of the size. However, in this day and age i thought it quite possible.

LBRC · Post by **LBRC** » Fri Apr 13, 2007 9:12 pm

As is the Atomic BB is still worth the $10 to $11 bucks, it only really sucks on principle.

DIY, if they can’t you can.

Stock

Atomic BB (no ball bearings)

Atomic BB (bushings replaced w/ 2x4x1.5mm ball bearings)

Note: Because of the extra transmission gears and relatively low current delivery form the 150 to 160 1/3aaa NiMH cells or even smaller LiPo’s a lower current motor can actually be faster in a stock Micro-T.

Ok, just put the BB modified Atomic BB in the LIT modified Micro-T (nothing stays stock for long around here) and holly cow it should not make that much difference with just the 10 tooth pinion? All I can say is wow I felt like the kid in The Incredibles when something amazing finally happened.

So now I’m royally pissed off, after seeing what the Atomic BB can do with actual ball bearings I can’t think of any excuse short of industrial sabotage for it not to have them even at twice the price. Sure initial sales might have been slower but as soon as Joe Consumer saw what it could do he’d find the cash.

There is one minor problem, to get the ball bearing on over the knurled shaft you need to sand it back down to the shaft diameter which means that you need to glue the pinion on but big scrap the knurling and special sell pinions, much easier and cheaper than installing FETs in a Mini-Z to run and Atomic Z2.

So Atomic RC are you listening? This is a no brainier:
1. Rename the Atomic BB to the Atomic ST, standing for Atomic stock.
2. Sell a true ball bearing version, and call it the Atomic SB (you can’t use BB because you already screwed that up.)
3. Then move up ½ of a wire gage (drop a few winds) from the SB so that the current drain with the ball bearings is equal to a stock Losi Micro-T motor’s current draw and call this monster the B1, yes this motor will need high temp bearings but believe me it will sell even if it costs as much as one of your Z2’s.
*. If you have to indent the knurling and sell pinions with slightly smaller bores so be it.

LBRC · Post by **LBRC** » Tue Apr 17, 2007 1:17 am

Ball Bearing Micro-T Stock Motor Too

O.67 amps no-load at 4.8 volts compared to ~1 amp, especially since often during a 2 minute run it dipped down into the low .50’s.

I also did a little commutator work, by turning it on a precision lathe the commutator is now perfectly centered (true) to the rotation of the shaft.

Would love to see how it does in a stock Micro-t lol unfortunately I no longer have one, stock that is.

Ok so that’s about it, except for the unimportant ball bearing motor in the middle

crazydave · Post by **crazydave** » Tue Apr 17, 2007 8:01 am

Alright, let me get this straight, so the Atomic BB is a hotter motor than stock, but is not even hitting the same RPMs as stock because its drawing too much current?

And we saw a pretty good jump in RPMs with bearings, do you think speed would increase on the BB after the bushings wore in a little more?

So, do you have any intention of selling ball bearing modded motors, or is that such a hassle that the money hardly makes it worth your time?

Thanks for the detailed write up. Nice to have the facts.

LBRC · Post by **LBRC** » Tue Apr 17, 2007 9:38 pm

Will try to keep this short and less confusing.

For now just assume that the no-load RPM on all motors are more or less equal. Yes it appears that the atomic has approx. ½ of a wire gage larger wires, meaning a few less turns but due to variations between individual motors and the extreme high RPM accuracy is suspect and the RPM value is more or less meaningless except as a ball park figure. As a very rough example pretend these motors are massively supped up 700hp 4-cylindar’s running at full throttle, without a load the motor is actually spinning fast enough to overheat and damage itself, they need a load to slow them down enough for usable test results. The 50,000 RPM ball park seems to be about what I would call a redline figure for this size and type of motor, unfortunately I posted in several different threads and forums without regard to what was left out where so one of the missing pieces of data here is that when I run these motor up to 7.4v without a load at around 60 to 69k they self destruct. So for now the motor monitor readings have to be combined with actual on road observations to qualify the data, especially with a limited number of motors to compare. Am working on a way to introduce an artificial load approximating the motor conditions running in a Micro-T on smooth pavement (i.e. battery drain/ WOT runtime time = ~motor current draw, averaged over repeated tests then recreated by the artificial load). But until then the next step will be comparing the motors hooked to the monitor but installed in a McT sitting on the old Speed Checker which although not accurate as actual driving conditions will at least yield an accurate comparison between the different motors, with a partial (drive train) load.

So for now current drain is the important value, showing that in both motors the ball bearings are making a substantial difference. Notice that that for the Atomic .97A - .79A = .18A or a 180mA reduction, and for the Losi Stock 1A - .67 = .33A or a 330mA reduction. The difference between the reductions, 180mA and 330mA, may appear significant but they are actually not remember I used a few slot car motor tricks to make the stock motor run smoother in addition to adding the ball bearings, but in the Atomic BB I just added the ball bearings.

To date what I do know, taken with a grain of salt that is:

1. The Atomic motor is faster in a car than the stock Micro-T motor, but still draws less current on the motor monitor without a load, and that upon examination the internal wire resistance is slightly lower and the wire gage although close appears to be just a hair larger than stock, that combined with the on the road in car observations using a 250mAh LiPo to remove current limitations as a major factor lead me to believe that it does indeed have just a few less turns but also has a slightly smoother turning armature than most unmodified stock motors. Someday someone will unwind one accurately to let us know exactly how many turns it has, but right now I don’t feel like sacrificing a perfectly good motor.

2. When ball bearings are added to both motors they show definite decreases in current drain even without a load, and when put in cars for actual testing that difference becomes more pronounced, they not only run longer but also appear to be faster too which although not normally expected when adding ball bearings is still quite possible/explainable when considering size, motor speed, and load.

Recap:
Stock = Fast

Atomic BB = Faster for the same if not less current. Possible reasons why? Smoother turning armature with bigger bushings nicer commutator, and likely larger gage wire, with possibly a few less turns.

BB Stock = Faster still due to less speed loss due to internal friction and peak operating efficiency, noticeably longer runtimes.

BB Atomic BB = Fastest, with good runtime, but does draw more current than the BB Stock, so if you are using large gearing with a crapped out NiMH or stupid cell phone, i-pod or other less than desirable for example 160mAh LiPo's the BB Stock could in such circumstances be faster.

All info, suppositions, and conclusions are subject to change as further info becomes available, however that disclaimer aside so far adding ball bearings to a Micro-T motor seems to be making a huge difference greater than in any other RC car/motor I’ve ever seen. Which is why I am now finding it hard to forgive Atomic for not putting BB’s in the Atomic BB even though they still seem to be worth eleven bucks.

crazydave · Post by **crazydave** » Tue Apr 17, 2007 11:10 pm

Well, that all made sense to me. I don't always get what the numbers mean, but I know when I just tried my car that motor was definately a lot snappier than stock.

Well worth the money to me, but I understand why you're bothered by the name, it is misleading. Hopefully they hear your pleas and release a ball bearing version. I'd be all over that. They could call it BBBB.

pimpsmurf · Post by **pimpsmurf** » Mon May 28, 2007 8:48 pm

The BB on the Atomic motor stands for "Brass bushing" The stock motor looks like, but is not brass, and as such the finish is not as smooth which causes more friction and current drawn. Thanks for the info on bearings! I have got to get my hands on a set for my atomic motor.

-JNY

crazydave · Post by **crazydave** » Mon May 28, 2007 8:49 pm

Where do you guys get your bearings for these?

pimpsmurf · Post by **pimpsmurf** » Mon May 28, 2007 9:07 pm

I've not been able to find that size bearing either. Anyone have the hookup? Atomicmods has (massively overpriced) ceramic ball bearing kits for this guy for around $30 shipped.

-JNY