Doahh

Unstickied by Foxy on 21/5/2013, all information now way out of date...



Well guys I'm making a How To thread for all the members and newbies that may have a question regarding something that might be in here.

I need you guys to make me some How To's like:
How To: Cut a Comm
How To: Build a Battery Pack
How To: Change Brushes
etc.

So PM me a how to with the subject
"How To: 'build a battery pack'"
But don't put Build a Battery pack there unless it is on doing that!

How To Build A Race Battery Pack
Thanks To: Speedmunkey
http://www.rcuniverse.com/magazine/a...article_id=481

Doahh

How To Select The Proper Pinion and Spur Gear Size
Thanks To: SkrapIron
http://www.rcuniverse.com/forum/m_3255405/tm.htm

What is the best set-up for my truck? How fast will it go?

These are questions that have haunted me for nearly 10 years. I have been running 1/10 scale R/C trucks off and on, without a real good understanding of how to properly set it up. To me, it was FM ( friggin magic). What pinion should I use? What if I change the spur gear? It was all trial and error that resulted in several melted motors, blown ESC’s and damaged batteries.

But I have found the answer! And it is good!

Question 1: What size spur gear should I run? What about the pinion gear? Well……. When selecting the spur gear and pinion gear size, you need to understand that there is a ratio between the tire circumference (referred to as roll-out) and the final drive ratio. That ratio, in most cases, should be as should be as close to 1 to 1 as possible. 1 to 1? What? By a 1 to 1 ratio, I am referring to the distance traveled by the tire in one revolution to the number of revolutions turned by the motor. In other words, if the motor turns X number or RPM's, the wheel will turn at Y RPM's, which is reduced by the final drive ratio. (A 32000 rpm motor with a final drive ratio 10.9893 will turn the tire at 2912rpm). For the sake of efficiency, the vehicle should be geared so that tire should travel approximately the same distance for every revolution of the motor, reduced by the final drive ratio. Here’s how it works. We’ll use my RC10t3 as the example vehicle. The first thing to consider is the diameter of your tire. It is used to calculate the circumference of the tire. Multiply the diameter of the tire by pi. ( Ex: 3.25�xpi=10.2101�) Now, you need to consider the final drive ratio of your drive train. Begin by dividing the number of teeth on the spur gear by the number of teeth on the pinion gear. This will give you your drive ratio. ( Ex: 87/19=4.5789). Now multiply your drive ratio with your transmission gear ratio ( Ex: 2.4x4.5789=10.9893 ). This is your final drive ratio.

Now the magic part. Subtract the final drive ratio from the roll-out of your tire . (Ex: 10.2101-10.9893= -0.77926) That is VERY close to a 0, but is geared a tad to the torque side of the motor ( anything below 0 is always geared towards more torque). Want more speed than torque? Redo your calculation adding another tooth on the pinion : ( Ex: 87/20= 4.35 ( drive ratio )x2.4 ( transmission gear ratio )= 10.44 ( final drive ratio ) Then subtract your final drive ratio ( 10.44 ) from your roll-out ( 10.2101 ) ( Ex: 10.2101-10.44= -0.2299 ) This is your optimum gear ratio, since it is closest to a 0 margin. Any ratio that is greater than 1 will run faster, but will overheat your motor, battery and esc, eventually damaging them.

How do we know this works? We can check out math by multiplying the roll-out of the tire, by the number of RPM's delivered to the tire, via the transmission. (Ex: Vehicle Final Drive Ratio is 10.44:1 and the roll-out of a 3.25" tire is 10.2101 " X 3065 rpm= 31294rpm) The motor's peak RPM is 32000, which means that we have less that 3% loss in efficiency from the motor, through the gear train.

Overgearing a vehicle will add to the speed of the vehicle, but it does so at a tremendous cost. The additional strain placed on the motor by the shorter gearing, will cause tremendous heat build up as the motor struggles to reach its peak RPM.

While this formula is not absolutely perfect, it does allow you to select a safe, and scientific starting point, to determine what is the best gearing combination for your particular vehicle.
This formula works best with 1/10 scale vehicles running stock to mid-modified motors. ( 27 turn to around 12 turn motors ).
Hotter motors 12 turn and lower will require you to reduce the ratio by as much as -1 or even lower to combat heat build-up.

We have simplified this equasion, by adding a Gear Wizard Calculator. All you need to do is add the right entries, and the calculator does the math for you!

http://www.rcuniverse.com/community/gearwizard.cfm

Question 2: How fast will it go? Well, we have half the equation already. Using the circumference of the tire divide that by the final drive ratio. ( Ex: 10.2101/10.44=.977797) multiply that number by the maximum working rpm that your motor is capable of. Most motors are rated at XXX RPM, XXX rpm/volt, or XXXk/v. With the peak RPM rating, simply use that number, unless you are using a higher voltage cell. For RPM/v (k/v) you simply multiply its number of RPM/volt by the number of volts supplied to the motor. I have a Trinity Jade 15 turn motor. It is rated for 28,500 rpm. @ 7.2 volts. ( Ex: .977797*28500= 27,867.2145 inches per minute )
Convert that sum to feet per minute by dividing by 12 ( 12 inches in a foot) ( Ex: 27,867.2145 /12=2322.2678 feet per minute ). Now multiply your feet per minute by 60 minutes ( Ex: 2322.2678 *60= 139,336.0725 feet per hour ). Now divide your feet per hour by 5280 ( the number of feet in a mile ). ( Ex: 2322.2678 /5280= 26.389 miles per hour ). Keep in mind that this number is entirely theoretical and is affected by the age of your motor, condition and charge of your battery, friction and or slip from your tires etc. Despite this, it is a pretty good estimate of just how fast you can go with a given motor!

So, the key to speed and longevity is a high rpm motor coupled to a properly geared drive train. It will make for many a happy afternoon of backyard bashing with your truck!

Doahh

How To choose a Motor, ESC/MSC and Brushed vs. Brushless systems
Thanks To: Elmo6s
http://www.rcuniverse.com/magazine/a...article_id=505



“Basics of choosing a motor and ESC/MSC and Brushed vs. Brushless Systems�

There are always a ton of threads about motors and ESCs and they are all usually variants on the same questions. In this article I will go through and explain the basics of choosing a motor and ESC/MSC, and talk about brushed vs. brushless systems.

When choosing a motor it is important to choose one that meets your abilities and budget. The first thing to consider when buying a motor is how fast you realistically want the car to go. I know you all want your cars going 50mph, but there are only a few of us who have enough driving experience to go that fast without hitting straight into a wall. The basics on turns and winds are as follows:

Lower Turn = Higher Top End/Less Torque
Higher Turn = Lower Top End/More Torque

As you look at motors with lower winds, you begin to see motors like a 9x3. This means that the motor is 9 turns and has 3 winds. The winds are simply for more speed, the more you have, the faster you go. One thing to note about lower turn motors is that they need a lot more maintenance. You can probably run a stock motor (27T) for 15-20 runs before it needs to have the commutator cut. On the other hand, a 9T motor needs to be cut every 3-5 runs.

There are a few classes for brushed motors:
Stock (27 Turn)
19T Spec (19 Turn)
Unlimited (Any amount of turns)

Your hobby shop or race track may have others, but these are the common ones.

Choosing whether to get an ESC or MSC is an easy decision. Get an ESC. MSCs (Mechanical Speed Controls) are very outdated and cannot handle today's motors.
When choosing an ESC you truly have to rate your skill level. While you may have a 19 Turn motor today, will you be changing to an 8 Turn motor soon? The answer is probably not. An ESC's limit is the lowest number of turns that it can handle. Now you have to make a big decision. Since ESCs that can handle lower turn motors are more expensive, you will have to decide how low you're gonna go. It makes no sense to buy an ESC with no turn limits if you are going to race Stock and 19 Spec, nor does it make sense to buy an ESC with a 17T limit if you are going to race Unlimited. This is basically up to you (and your budget), but be reasonable and get an ESC with a limit that is around your skill level.

My final rant will be on brushed vs. brushless. While these systems are in relatively the same price range, they each have their own pros and cons. A brushed system needs a lot of maintenance, but offers more flexibility because you can change motors depending on track conditions (how much torque you need). A brushless system on the other hand, needs almost no maintenance.

There are two basic decisions you need to make when buying a brushless system. How much can you afford to spend and how many transmission gears you want to replace. The Novak systems are more affordable, ranging from about $180-210 and include both a motor and ESC. The next level up would be a Warrior/Feigao combo which will be about $250 and will have more power and a nicer ESC. The highest level of brushless are the Hackers, Lehners, and Shulze. These are not for novices, and must be geared almost perfectly. These systems can range from about $400-800 for just a motor and ESC. Also note that the Novak and Warrior/Feigao combos offer better customer support and are easier to get.

I hope this article has answered most of your questions about motors and ESCs. Good luck, and have fun!

Doahh

How To Post A Picture
Thanks to: Mayhem Maniac


*Click "post reply. There is a link below the text box that says 'Click here to upload!'. When you click on that, it says 'Select a file to upload'. Below it are ten or so boxes. Next to the boxes are buttons labeled 'Browse'. Click on this. it opens a box, named 'choose a file' up top. Next to the words 'Look in:' is a box that you click on, and you can choose the folder you have the pictures in. (ex. picture in the C: drive) Once you have selected the picture, click 'open'. This will Bring you back to the 'Select a file to open' box.
Down at the bottom, is a box labeled 'OK'. Click that. It pops up a smaller box with the words:

*"Select a file to upload:
*Max. 3000KB;
*gif/txt/jpg are supported
*Please wait for the confirmation message to appear.
*On a slow network, it may take up to several minutes. "

*Once it's done, the box displays the words 'File Uploaded Successfully'. You type in the text box what you want, like you normally do, and when you click the 'OK' button like you normally do, there will be a picture in your post. Voila, and that's how you post a picture.

jakjr

My Feedback: (18)

Understanding Electric Motor Basics
Thanks To:SkrapIron and AS-EE

It happens every time I complete a run with my electric powered truck at the track. Almost all of the other trucks and buggies that are run there are nitro powered. I constantly hear comments like, “Man, that thing’s fast, for an electric.� “It’s so quiet.�

It really doesn’t surprise me any more, since there is such a grave misunderstanding of just how electric motors work. Most enthusiasts have a good understanding of the internal combustion engine, but to those same people an electric motor is an enigma.

In our hobby, we use a permanent magnet direct current (DC) motor. All of these motors operate from the DC voltage supplied by a battery pack. The battery chemistry can vary greatly, and what type is chosen can dramatically affect the performance of the motor. At the core of these motors lie magnets that are typically made of iron-ferrite or, less often, a rare earth material such as neodymium.
Lower-cost iron-ferrite motors usually employ oiled bronze bushings to support the ends of the armature shaft and stamped-metal can housing. Better-quality motors use stronger but more expensive rare earth magnets and almost always have ball bearings to support the shaft in machined housings. Motors will vary greatly in their physical size as well as their capacities, so selection of a proper motor for your application is critical.

The DC motor is broken into 2 distinct components. The stationary parts of the motor, collectively called the "stator," include the magnets, brushes, brush hood, and springs. The rotating portion or "rotor" includes the commutator plates, armature and windings. The motor's job is to convert stored electrical energy into mechanical energy. It does so through the process called commutation. Commutation occurs when a portion of the windings on the armature are energized in any one position. As the motor’s position in the magnetic field changes, the brushes connect to different windings through the commutator plates. The brush motor is designed so that the optimal windings are energized in every position.

Brush motors are most often identified using the number of turns and winds with which it is constructed.
A turn refers to a complete wrap of a coil of wire around an armature arm (15 turns means 15 loops of 1 wire on each arm). Higher number turns will be slower because more copper coils are exposed to the magnetic flux lines of the stator magnets. This will cause a greater amount of counter-voltage to be induced when the armature "cuts" through the magnetic lines per unit time. Counter-voltage then subtracts from supply voltage in the armature coils, and this will in turn cause your armature coils to have less current flowing through them which results in a slowing of rotational speed. A lower number of turns will be faster, since fewer copper coils are exposed to the flux lines of the stator magnets. It is in these applications that higher flux density magnets, such as neodymium, can be used

A wind refers to the number of strands of wire, wrapped around the armature, in 1 turn. In general, winds with fewer wires give greater starting torque and better acceleration, but lower top end. Conversely, higher winds with more wires will have less starting torque, but higher top end.

A brushless DC motor functions a bit differently than its brushed counterpart. In a brushless motor, the permanent magnets are mounted on the rotor. The windings are stationary and attached to the motor's outer case. Since it is now the magnet that is turning, instead of the windings, the commutation must be done electronically rather than mechanically. An integrated sensor circuit in the motor, along with the microprocessor in the Electronic Speed Control, controls commutation. This control is delivered by calculating the rotor’s position, and determining how to channel the current to supply the requested torque with minimal current. These sensor based motors provide the smoothest and quickest delivery of torque, but are limited in their RPM potential. Several DC brushless motors forgo the integrated sensor circuit in favor of a 6 step drive. Six-step drives channel current into only two windings at any one time. This simplifies the design and construction of the drive. However, the torque produced by six-step drives has more ripple and is produced less efficiently, compared to sensor based brushless motors.

Brushless, sensorless motors with three connections are in fact, not DC motors at all. They are actually permanent magnet synchronous AC, 3-phase motors. The ESCs that control them, have three distinct semi sinusoidal waveforms (not pure sinewave AC) that come in at different times (or degrees) which causes the rotor to rotate with the changing (alternating) magnetic fields of the stator. While this is still not as smooth in operation as a sensor-based motor, it does allow for tremendously greater power, and a much higher operating RPM.

Brushless motors are inherently more efficient than brushed motors for multiple reasons. Since there is no mechanical commutation, there is no wasted energy from friction between the brushes and commutator. There is also no loss in efficiency due to the build up of contamination on the commutator. Additionally, because the windings are physically mounted to the outer case, heat is more efficiently drawn away from the motor.

For any motor, either brushed or brushless, the voltage that is supplied to the windings controls the speed of the rotor. This supply is referred to as the voltage constant, which is represented with the symbol Kv. Kv is the rpm per volt that the motor will produce. (Kv x Volts = RPM) The higher the Kv, the faster the motor shaft will turn for each volt applied. But judging the performance of a motor solely based on its voltage constant (Kv), is a mistake.

Along with the Kv of the motor, there is something else to consider. Every motor has a torque constant (Kt). Kt is the amount of torque the motor can deliver to the pinion shaft, and is rated in either ounce/inches or Newton millimeters per amp of current. What is difficult to understand at first is that the Kt is inversely proportional to the Kv of the motor. That means, as the Kv of the motor increases, the Kt decreases. It therefore stands to reason that a high Kv motor cannot deliver as much torque as a similar-size lower Kv motor.

When a DC motor is energized, it draws a large initial surge of current. The surge is caused because the motor, when it is turning, also acts as a generator. The generated voltage is directly proportional to the speed of the motor. The current through the motor is controlled by the difference between the battery voltage and the motor's generated voltage, otherwise called back EMF. When power is first applied to the motor, there is no back EMF. That means that the current is controlled only by the battery voltage, battery internal resistance, motor internal resistance and the battery leads. Without any back EMF the motor, as it starts to turn, the motor draws the large surge current. This surge of current is what generates huge amounts of initial torque. As the current flow evens out, with the back EMF, the torque curve falls off proportionally.

jakjr

My Feedback: (18)

Cut a Commutator
Thanks To: Myself

In this how-to I will cover the methods I use when cutting a comm. I do not claim for these to be "correct", this is simply how I do it and it works perfectly fine for me.

I'm not going to get into how to set up your lathe as that's beyond the point of this how-to, but I will say to make sure it is running in the correct direction, and make sure the bit is aligned with the comm correctly or you WILL have problems getting a good clean cut.

First you will obviously need to take the armature out of your motor and install it in your lathe. You should also shim the armature (if needed) to prevent it from bouncing/sliding back and forth in the lathe.

Once this is done I turn on the lathe and use a dark colored sharpie marker to color the whole comm. The point of this is to make the low spots on the comm easily visible once you start cutting it, so you know if you need to cut more off to get the comm completely level.

Once the sharpie has dried on the comm, I put a drop of cutting fluid on it and begin cutting. Turn the lathe on and slowly turn in the depth adjuster until the cutting bit just contacts the comm, then take two passes across the comm, turn off the lathe, and check for low spots on the comm. If there are low spots, turn the lathe back on, turn the depth adjuster in a notch, and make two more passes across the comm. Repeat this until the comm is completely level with no low spots showing. Once the comm is completely level I then take a few more passes across it to smooth it out off needed. NOTE: You may need to periodically stop to clean off the comm/cutting bit if copper "chips" start building up on them.

Once the comm has been cut you will then need to use a razer blade, exacto knife, etc. to clean out the grooves between the comm plates. Typically they will get full off copper "chips" which would cause the motor to short out if they were left in the grooves. Once the grooves have been cleaned out, I take a ball point pen and run it down them pressing relatively hard, this smooths out any rough edges left from the razor blade, and also chamfers the edges of the comm plates which helps prevent the possibility of a brush getting hung up on one.

Once all of the above has been done, I then take something lightly abrasive such as a comm stick, comm pen, eraser, etc. and lightly buff the comm until it has a dull finish. Supposedly this helps to keep the comm from getting "glazed" as quickly.

After everything above has been done, the armature is ready to go.

jakjr

My Feedback: (18)

Changing Brushes...
Thanks To: Myself

Changing out motor brushes is relatively straight forward, and as such this How-to will be relatively short.

First things first, take off the old the brushes. This is done by removing the springs then either unsoldering the shunt from the brush hood, or unscrewing it from the brush hood. Typically the soldered on method is used with higher quality motors, but many prefer the screw on method for simplicity. As far as I am concerned, the method used really makes no difference as most of the power is transfered to the brush through the brush hoods and not the shunt to begin with. Supposedly the shunt can only carry about 10amps. But in either case, I always use the solder on method, maybe it does make a difference, but if it does I can not tell it.

Anyways, once you've got the old brushes out, it's time to install the new ones. Screw the terminals to the brush hood, or solder the ends of the shunts to the brush hoods, stick the brushes in their hoods, install the springs, and they are ready for break in.

To break in the brushes, simply run the motor on a low voltage source (I use the 3.3 volt tap on my power supply) periodically checking their progress. The motor should be ran until the whole face of the brush shows wear and/or arcing is very minimal. Typically this only takes a minute or two depending on the type of brushes. Some people also do a "wet" break in where you drop the running motor in a glass of warm water for about 10 seconds, but this is not how I do it nor how I recomend doing it.

Doahh

How To Rebuild a Motor
Thanks To: Speedmunkey

Materials:
* Integy Super Auto Lathe
* comm cutting fluid (it's all just light machine oil, pick a bottle and go with it)
* ball point pen (for easing the edges of the comm plates)
* X-Acto knife (always clean the copper shavings from between the plates!)
* RPM motor stand
* break-in fan
* 4c pack with alligator clips
* motor spray (non-chlorinated brake cleaner works just fine for 1/3 the cost)
* Q-Tips (for cleaning the brush hoods and the endbell, get the foam ones if you can. The cotton ones can leave fibers behind)
* magnetic parts tray
* phillips screwdriver
* Sharpie (for both marking your timing, the + side of the can and for coloring the comm so you can see where you've cut it. I use blue, cuz black sharpie looks just like burnt comm..)
* large Cool-Whip bowl



Now, my 38 simple steps for actually rebuilding the motor ....
1.) Take the Sharpie and mark the + side of the can and mark your previous timing. I also put a + on one end of my parts tray and a - on the other.
2.) Open the can with the phillips screwdriver. Place the screws and anything attached to them in the magnetic parts tray.
3.) Remove the springs and place them in the tray. Springs are usually different on the + and - sides, so put them on the proper ends on the tray.
4.) Pull the old brushes out of the hood and let them flop.
5.) CAREFULLY pull the endbell off the can, and collect any washers that are stuck to the bearing. Pay very close attention to the washers/shims you find. Getting these back in the right order is critical to maintaining consitent performance across builds. I lay my shims out in the tray in order, going from + to -, always ending with the fiber washer cuz I know it touches the comm.
6.) Take the screwdriver and rotate the timing ring so it comes out, then place it in the tray.
7.) Pull the arm and make sure no shims fell into the winds. Pull the shims off the bottom of the arm and place them in the tray.
8.) Look down into the can and see if any shims got in there. Check the magnets carefully. Also check the bearing to see if a shim go left behind.
9.) Put the arm in the lathe and turn it on.
10.) Apply the blue sharpie to the comm.
11.) Bring the bit to the comm as slowly as possible until you skim a faint line on it.
12.) Make however many passes it takes to remove all the Sharpie and charred copper. It should look like a new penny when you are finished.
13.) Take the X-acto knife and clean out the shavings from between the comm plates.
14.) Take the ball point pen and run it fairly forcefully along the edges of the comm plates. You are trying to round the edges over so it wears better and is easier on the brushes.
15.) Put the arm over the Cool-Whip bowl and blast it with the motor spray/brake cleaner. Be generous here, clean is fast. Spray till it runs off clear.
16.) Do the same thing with the can, timing ring, then the endbell. Be generous here, clean is fast. Spray till it runs off clear.
17.) Oil the bearing in the can.
18.) Put the can in the RPM motor stand, vertically.
19.) Replace the shims on the bottom of the arm, and put it in the can.
20.) Grab the endbell and a few Q-tips.
21.) Spray motor cleaner on a Q-tip and swab out a brush hood.
22.) Turn the Q-tip around, spray it, and swab the same hood again. Do each one twice, or until the Q-tip comes out clean.
23.) Throw that Q-tip away, and get another ones. Repeat steps 22 and 23 for the other brush hood.
24.) Grab yet another Q-tip, spray it, and attack the endbell innards. Spray it out, swab again, spray it out, swab again, etc... Be generous here, clean is fast. After that, Oil the end bell bearing.
25.) Replace the timing ring. (side note on the timing ring. If you over-tighten these, they'll warp. A hammer is your friend here. Bang it till it's flat)
26.) Replace the shims on the top of the arm.
27.) Replace the endbell on the can, being careful not to hit the shims.
28.) Line the holes on the end bell and timing ring up and start the screws.
29.) Rotate the end bell back to the original timing, and tighten the screws.
30.) Desolder the old brushes.
31.) Solder on the new brushes. (Hint: A small pair of pliers and a 90 degree bend in the brush shunt will keep the solder from wicking up into the brush shunt.)
32.) Put the brushes in the hood and replace the springs.
33.) Orient the motor stand horizontally and put the break-in fan on it.
34.) Attach the 4c battery to the motor and let it run 30 seconds. Watch that fan, it's dangerous!
35.) Pull the + and see if it is shiny all the way across. Repeat 34 until the entire face of the brush is shiny.
36.) Once it is shiny, pull the brushes out and blast the motor with spray.
37.) Let the spray dry compeletely, then put the brushes back in.
38.) Hit the motor for a final 30 seconds on the 4c pack and you are good to go racing.
Simple as that........ Sounds like a lot, but it's easy once you've done it a few times.

Doahh

How To Waterproof Your Car
Thanks To: about.com

1. Prepare the vehicle:
Before you can head out, you need to protect all the important parts. The servos, ESC (electronic speed controller), the nitro engine or electric motor, receiver and receiver pack, along with the batteries (and connectors). Be warned, if water gets into any of these parts, you can cause a short at the very least, or ruin the more delicate parts. In addition, anything plastic will quickly become brittle and snap or crack easily while exposed to extreme cold.

2. Protecting the Servos:
Some servos are waterproof, and will probably not need any more attention, but check them over anyway. To protect the servos, remove the server arms and anything attached to them. Use a balloon (or other waterproof bag), and carefully stretch it over the servo. Let the wires outside the mouth of the balloon and then use zip ties to hold the mouth closed. For added protection, seal the balloon mouth with silicone before attaching the zip tie.

3. Protecting the ESC:
You can use the same method to protect your ESC. Be careful not to stretch the balloon overly tight on this part, as the ESC often has near-sharp edges and can cut open the balloon or bag during operation. The other problem you discover is overheating. The balloon method does not allow for any air circulation, so monitor the temperature often. It takes very little water (or over-abundance of heat) to destroy your ESC.

4. Alternate Method for the ESC:
Another way to protect your ESC is by using a shield, rather than a balloon. To fashion a shield, you can try the method that I use. These days, in boxes of clothes detergent, they have a plastic scoop. You can trim the edges (and the handle) off of the scoop, and it fits almost perfectly over some ESC. Just place it over the electronics you want to protect, then use some tape to seal any gaps around the edges or underneath. Trim away anything that gets in the way.

5. Protecting the Batteries and Wiring:
Use some electrical tape or some silicone on all exposed wires, leads or anywhere that water can come in contact with the electrical system. I prefer silicone because I can peel it off after operation. Just apply it to one side and let it dry completely, before applying it to an opposing lead. Silicone starts off wet, so make sure nothing has power running through it when you do this.

6. Protecting the Receiver and Receiver pack:
Most vehicles have a cover for the receiver pack already, but make sure yours is waterproof. Nitro vehicles usually already have a waterproofed receiver pack to protect them from nitro during refueling. If you have an electric, or do not have a receiver cover, get one and install it, then seal all the holes where the wires and leads pass through. Just use some silicone and you should be fine. As with all parts, monitor for water or dampness often.

7. Protecting the Engine:
Your engine may not want to preform in cold weather, and it is important that you do not over-lean the engine to get it to run hotter. If you do, you will lose lubrication and this can damage the engine, or the piston and sleeve. To contain the heat needed to sustain operation, you can wrap it in a paper towel or a bit of cloth. If you do though, make sure you monitor the engine so that it doesn't run too hot. Make sure the carb or the air intake is not obstructed.

8. Protecting the Motor:
You won't need to cover the electric motor during operation, since water is unlikely to affect it at all. I prefer to make sure my motor is well lubed and clean before I run it in snow. After operation, you will need to disassemble it again, clean it up and relubricate everything again if necessary. Just make sure it is dry before putting everything back together again.

9. Receiver and Transmitter Batteries:
If the "AA" batteries in your receiver pack or transmitter seem to be failing or your ride responds sluggishly, you can remedy this by warming them up, either by going inside for a while, or switching them out with a spare set that has already been waiting inside, all nice and warm.

-------------------------------------------------------------------------------------------------------------------

Tips:

1. Do not operate your RC vehicle in extremely cold, or wet weather without protecting it. Make sure you have covered all parts that can possibly get wet or frozen. None of these tips are 100% certain to work, and if you overlook them, or do not completely protect your RC vehicle, you will cause some damage. Most warranties do not cover RC vehicles operating in such conditions, unless of course your vehicle was designed for water or snow.
2. If you are using a nitro engine, start it up inside and let it warm up before heading out. This holds especially true if your engine is the type that is already difficult to start. Let's face it, we'd all love to have an engine that starts the very first time, but this is not always the case. Being outdoors in cold weather will only make the engine harder to start. Cheat... Start it, and let it warm up, before ever exposing it to the cold.
3. If you are just assembling your kit, or have not yet performed the initial engine break-in, do not even consider running it in the snow, or under any cold or wet conditions. In cold weather your engine will not break-in properly, and you will most likely cause permanent damage to the engine. Engine break-ins must be done so that the piston and sleeve properly mate together, which requires temperatures that cannot be realized in the cold. Wait and do this on a dry, warm day.
4. Consider running your ride without the body. Sure, it may not look as pleasing, but the lexan, fiberglass or plastic type bodies may become brittle quickly and will crack or shatter with even a minor impact or crash. If you need the body attached, to protect other parts for instance, just drive with care, and avoid high-impact stunts or jumps.
5. If you notice water getting into any of the electronics or your engine, stop and dry it immediately. If possible, take the vehicle indoors and use a heat gun to dry the parts thoroughly. Leaving the vehicle wet after operation is a sure way to damage something, allow rust to take hold or short out the electronics.

What You Need:

* An off-road RC vehicle, helicopter or airplane of your choosing.
* Balloons or Waterproof bags.
* Zip Ties or strong rubber-bands
* Waterproof tape, duct tape or some electrical tape.
* Heat Gun if available. (Optional but recommended.)
* Temperature Probe if available.

jakjr

My Feedback: (18)

How to calculate your cars internal gear ratio.
By: Myself

Calculating your cars internal (transmission) gear ratio is quite simple, however you will first need to find out how many teeth the differential gear and topshaft have. The differential gear should be largest gear in a three gear transmission (approximately 40-50 teeth), the topshaft should be the smallest (approximately 10-18 teeth) and should be easily picked out due to the shaft on it The center, medium sized, gear is called the idler gear, but it will not be used in the calculations. To find out the gear sizes you can either check the descriptions of them on a site like TowerHobbies.com, check your cars manual (many manuals will also provide you with the internal gear ratio), ask in the forums, or if all else fails open up the transmission and count the teeth yourself.

Once you know the number of teeth on the differential gear and topshaft all that is left to do is one simple math problem: Divide the number of teeth on the differential gear by the number of teeth on the topshaft. Example (BTW, this is using the Evaders gears) 48 (differential gear) / 18 (topshaft) ='s 2.666...7 (the actual number is very long so it would be best to round it off to 2.67 for use in other calculations).

There is a thread in the general car forum discussing internal ratios (posted by studysession), it also has them listed for a number of cars, however the list hasn't been updated in over a year therefore many newer cars are not listed. I have included the list of ratio's in this post, whenever I get the time I will update it and remove any non electric cars. If you know the ratio of a (electric) car not listed PM me with the info and I will add it to this list.

Internal Gear Ratios: (* denotes aditions to the list that I have made)

jakjr

My Feedback: (18)

How to calculate battery pack charge time
Special Thanks to: bIGmiK


Some stuff for the not so mathmatical people:

A "/" is a "divide" sign.
A "*" is a "multiplication" sign.
1A = 1000mAh

The Equation:

A = Batteries Capacity in mAh
B = Chargers Output Currant
C = 60 Minutes (1 hour, pretty simple, eh?)

A / B * C = Amount of time to charge your battery

I have a 3.3A (3300mAh) battery, and a charger that charges at 5A (5000mAh).

This is how I would work it out:

3300 / 5000 * 60

What I would key into a calculator:

3300 "divide sign" 5000 "multiplication sign" 60

And 100% of the time, the answer it will give me is 39.6 minutes.



GP3300

0.1A = 1980 minutes
0.5A = 396 minutes
1A = 198 minutes
2A = 99 minutes
3A = 66 minutes
4A = 49.5 minutes
5A = 39.6 minutes
6A = 33 minutes
7A = 28.3 minutes

GP3700

0.1A = 2200 minutes
0.5A = 444 minutes
1A = 222 minutes
2A = 111 minutes
3A = 74 minutes
4A = 55.5 minutes
5A = 44.4 minutes
6A = 37 minutes
7A = 31.7 minutes

IB3800

0.1A = 2280 minutes
0.5A = 456 minutes
1A = 228 minutes
2A = 114 minutes
3A = 76 minutes
4A = 57 minutes
5A = 45.6 minutes
6A = 38 minutes
7A = 32.6 minutes

IB4200

0.1A = 2520 minutes
0.5A = 504 minutes
1A = 252 minutes
2A = 126 minutes
3A = 84 minutes
4A = 63 minutes
5A = 50.4 minutes
6A = 42 minutes
7A = 36 minutes

Doahh

How To: Solder Deans
Thanks to Hunter306

1) Heat up your iron (30watts +)
2) Prepare the tabs on which you will solder... Scuff them up with rough sand paper or a hobby knife.
3) Get a decent roll of solder, I use some Rosin Core High-Tech Solder from RatShack
4) Strip the wires which you are trying to solder to the deans plug. I don't suggest stripping more than a 1/4 inch (that may be a little much!)
5) BE SURE NOT TO TOUCH THEM TOGETHER (A Pair of helping hands alligator clip clamps works great)
6) Tin the ends of the wires, do not heat the solder -- heat the wire and allow the solder to flow around the wire.
7) If you have trouble getting the solder to flow, re-tin the tip of the iron and repeat step 6
8) Tin one of the two solder tabs on your now roughed up deans connectors (Tin the tip of the iron, firmly touch the tab and allow the solder to blob up on 1 of the tabs)
9) Allow the small ball to harden on the tab
10) Slide 1/4-3/8" of heat shrink tubing over the wire
10) Position the wire so that no tension is on it in any direction (AKA, it is laying limp on the table)
11) Place the tinned tab of the deans plug under the limp wire. It should sit on top of the tinned tab without any assistance.
12) Place your index finger on the wire which is resting on the tinned dean's plug tab. The wire should continue to balance on the tab.
13) Re-Tin your soldering iron and place it firmly on top of the wire (be careful not to push the wire off the side of the deans tab!)
14) Press down gently, as the solder on the wire melts, the solder on the tinned deans tab should melt (This can take a second or two)
15) Maintain contact until the solder on the tab/wire are liquefied -- Maintain a index finger pressure on the wire (TAKE CARE NOT TO MOVE THE DEANS CONNECTOR OR THE WIRE--- THIS IS CRUCIAL FOR A GOOD CONNECTION)
16) Allow the solder to harden
17) Slip the heat shrink over the newly formed solder joint
18) Heat and allow to shrink around joint
19) Repeat steps 8-18
20) You now have a cleanly solder deans plug

There you go, I think that's about as verbose as it gets. Good luck and try a little patience with the solder process!