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Effigy3

Brushed motor water break-in rig

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I wanted to build a rig that would allow me to easily and consistently break-in my motors. I ordered up a Traxxas MSC and mounted it to a cheap plastic foot stool with the screws that came with the MSC. I still need something to mount the resistors onto. My pencil jobber is pretty ghetto. :o Running the motor on low speed for 10 minutes really got them heated up resulting in one becoming cracked. Not sure if I can use it cracked or if I should replace it. Obviously 10 minutes straight at low speed is more than it can handle.

CLick here to watch my short video on YouTube.

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To cool the resistors, you could submerge them in water too! As long as the water is clean, it's almost not conductive at all. When the water gets contaminated, it will get somewhat conductive, but hardly enough to make a difference. After all, the low ohm value of the resistors means that the "short circuiting" current between the resistor terminals caused by (contaminated) water is still a lot smaller than the "regular" current through the resistors.

Or in other words, if running the motor in with the resistors submerged in the water, you may experience a slight insignificant RPM increase when the water gets contaminated. That's all.

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The 25 minutes total break in time seems a little excessive to me, but........

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To cool the resistors, you could submerge them in water too! As long as the water is clean, it's almost not conductive at all. When the water gets contaminated, it will get somewhat conductive, but hardly enough to make a difference. After all, the low ohm value of the resistors means that the "short circuiting" current between the resistor terminals caused by (contaminated) water is still a lot smaller than the "regular" current through the resistors.

Or in other words, if running the motor in with the resistors submerged in the water, you may experience a slight insignificant RPM increase when the water gets contaminated. That's all.

I actually considered this but the resistors lines are too short to reach into the bowl. Since you have confirmed that it's cool (pun intended) to submerge the resistors I'm going to rig something up to give them their own liquid cooling. Thanks!

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The 25 minutes total break in time seems a little excessive to me, but........

TBH I've never broken in a motor in this fashion before. I would just drive my car "slow" for a few minutes and then hammer the heck out of it. I found people reporting water break-in times anywhere from 5 minutes at full tilt to a full battery charge slowly ramping up the speed. So I built this contraption and aimed for the middle. I can say that the water kept getting darker right up until the last 5 minutes.

This was my first attempt doing this but I think I will cut the time down a little bit on motor 2. I think I'll do my next motor with 5 minute intervals at each speed (slow, medium, and high).

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What motors are you breaking in?

Dorvack.

For now, I'm doing the stock 540 since I've never before broken in a motor using water. I have one more stock 540 to break in then I'll do my Sport Tuned. I plan on getting a Dirt Tuned in the future, once I use up the Sport Tuned.

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The brushes on a stock 540 silver can are very hard - 20 minutes of submerged low-speed running was the norm when I raced in the silver can classes BITD.

The softer brushes on a Sport Tuned will need less time - about 5 mins was the norm when I raced them.

The brushes on most rebuildable motors are also quite soft - some of the really soft ones are broken-in in under a minute of submerged running, as the water accelerates the break-in process. I remember a chap at our club using a water break-in rig to break in a ROAR stock motor, wearing in and then completely wearing out a set of brand new soft brushes in less than 15 minutes of submerged running!

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The brushes on a stock 540 silver can are very hard - 20 minutes of submerged low-speed running was the norm when I raced in the silver can classes BITD.

The softer brushes on a Sport Tuned will need less time - about 5 mins was the norm when I raced them.

The brushes on most rebuildable motors are also quite soft - some of the really soft ones are broken-in in under a minute of submerged running, as the water accelerates the break-in process. I remember a chap at our club using a water break-in rig to break in a ROAR stock motor, wearing in and then completely wearing out a set of brand new soft brushes in less than 15 minutes of submerged running!

Thank you XV Pilot! I'll make sure to keep my breakin times down to 5 min on my Sport Tuned and to a minute when I finally get a Dirt Tuned. So glad I started this on silver cans.

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I was probably very "old school" on my water dipping procedure, and the process could well have evolved quite a bit over the years.. When I water dipped a 540 motor, the rule was to run the motor off a (partially) charged 7.2V battery, and dip the motor until the water started to go dirty/black, and then stop and check the brushes.. Dip again if needed.. I don't think that I ever had the motor submerged for more than 3-4 mins total, often less as I would usually get bored with standing there holding the battery and motor.. LOL... When you were finished, put a drop of your favourite oil on each of the bushings at each end of the motor..

I also found the water dipping process very useful for cleaning 540 motors, especially those used for off-road duties, just add a few drops of dishwashing liquid to the warm water....

I will agree with XV Pilot on the need for care when water dipping Sports Tuned motors though.. I once totally wore out the brushes in a Sports Tuned when cleaning it using the dishwashing soap/water dip method....

I have NEVER water dipped an open brush type motor, as the brushes were usually soft enough to do the bed in process without the water..

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I broke in the Sport Tuned motor today. I modified my contraption by drilling an 1 1/4" hole to allow the ceramic heat sink resistors to dangle freely below the stool. Before I had to use a pencil to prop them up so as not to touch the stool. It also placed them safely under the stool so that they didn't get touched accidentally. Those suckers can get HOT. ;) I decided to run in 2 minute increments so as to not over heat them and crack the other resistor.

03.21.2015-14.04.png

Here's a pic of the brushes after 2 minutes submerged running at LOW speed on the MSC. Notice the brushes have a V cut into them? The stock 540 had square brushes. This V is going perpendicular to the rotor so I can only guess that it's designed this way to expedite the break-in period.

03.21.2015-13.56.png

This is the motor with another 5-ish minutes of submerged running at HIGH speed on the MSC. I guess that cracked heatsink resistor is inop now because I can only run the motor at high speed on the MSC. Gotta sort out where to buy replacements. I checked on the brushes every minute and stopped once the V groove was gone and the brush was making full contact with the rotor.

03.21.2015-14.00.png

Boy oh boy did that water get dirty!

03.21.2015-14.02.png

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If you keep having overheating issues with the resistors and don't want to go for a fan or dipping them in water, get 4 resistors and wire them 2S2P. I.e. wire two and two in rows and connect the two rows in paralell. That will give you the same resistance and 4x the surface area to dissipate heat from.

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Alternatively, get a small 3V transformer and run it off mains. I used that method BITD and it worked just fine with no overheating. A transformer with short-circuit and thermal protection can be had quite cheaply from Maplins or a similar supplier.

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The old MSC resistors are only meant to be used in short bursts to avoid too much shock to the cars drivetrain. It even says inside manuals (either Tamiya or Kyosho) not to run old MSC models at part throttle for too long. Resistors quickly overheat when run for long periods of time. Especially with hotter motors.

For simplicity, I recommend regular 2-cell lipo with the motor wired between one power lead & the balance tap lead (I use bullet plug lipos). This runs the motor on only 1 cell of the lipo. I let the motor run at half voltage for a minute and then switch to the other lipo cell checking the brushes each time. Motors run at half voltage & zero load pull very little current so you don't have to worry about burning up wires or anything. So long as you balance charge your lipo, you won't have any problems with your batteries.

For rebuildable motors, I run in serrated brushes dry on 1cell lipo with the motor over a fan till all the serrations show contact with the comm. I also use my temp gun to monitor the brush & comm temps so they don't overheat.

Tip: To get even more performance out of "Fixed timing rebuildable race motors" (and stay within the rules), you can take an old brush and "square" off it's face with a file. Then run the motor briefly to see where on the brush face the comm makes contact. If the contact mark isn't in the center of the squared off brush, loosen brush hoods & give them a twist in the desired direction. Once you get the wear mark centered on the brush, cut the comm, install new brushes, and run the motor in. This compensates for the drag that causes the brushes to shift and slightly retard motor timing. Plus your brushes will wear straight down their center from now on. You can also get all "cheaty" and actually advance your timing with this method too.....but that's lame.

I really love the intricacies of this hobby.

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Is it just me, or does this sound like fun? I really enjoy tinkering with motors and engines, almost as much as operating the finished model. I know " brushless is better", but to me it's just a little antiseptic. Kind of like driving my wife's Acura...:)

Guess I'm just an old coot...

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you're wasting energy thru MSC's resistors

if you're keeping that 6c pack just for waterdipping, pop off the rear endcap and hookup to the cell tab... run motor off 3 cells instead of all 6... i used to run-in using only 2 cells; easiest with side-by-side ladderpacks.

Plus you'll get 2 or 3 runs per full charge! :)

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I've made some changes to my rig. Behold: Kelly's Liquid Cooled Water Dipped Brushed Motor Break-in Rig mark II (KLCWDBMBR m2). I think the name could use some work. ;)

First - I upgraded the small resistors to these jobbers.

05.28.2015-07.54.png

Second, in order to gain favor with the spousal unit, I bought a covered plastic measuring jug to replace the spendy Pampered Chef glass measuring bowl. I bored a hole in the lid over the pour spout using a body reamer. I pass the motor wires through this hole which allows the lid to seal. The pour spout works perfectly as a wire inlet to the jug. For added brownie points with my wife, I run it on a silicon hot pad which helps to muffle the noise of the motor as it spins at the bottom of the jug.

Third, I got a cup and filled it with water. The resistors dangle into this cup, but just barely. I need a slightly taller cup. ;) Keeping the resistors submerged allows me to run the rig at low and medium speed for as long as I want. The water went into the cup cool to the touch and came out feeling slightly warmer than room temperature.

05.28.2015-08.04.png

It works quite well now. Hardly any mess, acceptable noise level while in operation. I found that it works best with the jug filled to 32 oz with deionized water. I run the motor at low speed for about 30 seconds, medium for about 30 seconds, and high until the water turns cloudy.

05.28.2015-08.05.png

I broke in 4 motors last night, changing out the dip water between each motor. I used a gallon of deionized water in the process.

05.28.2015-08.07.png

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Have you considered using a slave rig? It would have a hard time working under water though...

Dorvack.

I don't know what that is. :/

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So I tried this one a new torque tuned, in 3 min increments of low, mid and high. When I finished, 75% of brush was gone 😂 

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So I tried this one a new torque tuned, in 3 min increments of low, mid and high. When I finished, 75% of brush was gone 😂 

  • Haha 1

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2 hours ago, Raman36 said:

So I tried this one a new torque tuned, in 3 min increments of low, mid and high. When I finished, 75% of brush was gone 😂 

So it’s almost a Brushless motor now then 😉

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So I tried this one a new torque tuned, in 3 min increments of low, mid and high. When I finished, 75% of brush was gone 😂 

 

🤣 😂 

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Yeah, that video is pretty old.  I should take it down and redo it right.  :/

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