Mouton
07-26-2008, 08:12 AM
Threespeeders and other Tamiya crawlers are great models for a walk in nature and the great outdoors. Some aim for the rocks, others for the puddles. For the latter group a fully waterproof truck means unstoppable action without worries. Keep in mind that you need not aim for the water in order to end up in it!
Some servos are sealed, but extremely few are fully waterproof (drown-able) and covered by warranty for such claims. Opening up a servo, receiver or ESC will void the warranty but waterproofing it will eliminate the biggest problem for us driving in the dirt to begin with. For those of you prepared to exchange the warranty for a waterproof model here are my top tips for how:
What do I need?/B]
The easiest way is by using rubber balloons around the servos, receiver and ESC. Sealing the open end with a cable tie (better yet silicone inside the opening and a cable tie) is good for servos and receivers but not for ESCs. The balloons are fragile and even worse, condensation might occur meaning that moist can be built up inside the balloon, making your electronics rust. In other words not the best way to go about it then.
If you want waterproof electronics you will have to open it up and waterproof it. Vaseline (e.g. Chesebrough) works and is widely available. The drawback is that it is not heat stable. If used during a hot summer day or in an ESC it will start to melt, thus diminishing its protective capability.
Silicone is water based and seals great, however it must be allowed to fully dry before anything is switched on. Silicone is conductive before it has dried. A minimum of 24 hours is recommended.
What I recommend is grease from the automotive industry. I personally use Würth WGF130, which is a German product for lubricating wheel bearings. Any garage/shop should have an equivalent product. Wheel bearing grease is the best way to fully waterproof electronics for RC use. It keeps water out, is heat stable (to all temperatures an ESC can generate) and does not lead any current. If you use any other type of grease than Würth WGF130 please do remember to check its lack of conductivity (with a multimeter) before you use it.
There are other products that also work fine, such as PlastiDip and various lacquers. However since all of them are even harder to find and more expensive than wheel bearing grease I will not cover them here.
How do I go about it then?
A toothpick or a matchstick are excellent for applying the sealant. A servo is very easy to open up and seal. Simply remove the four screws in the bottom and carefully remove the plastic bottom cover. Fill the servo with sealant and be extra careful to cover all sides of the hole where the servo lead exits. If your servo housing has an aluminum cooling head or consist of several plastic parts you need to carefully separate them and enter as much sealant as possible. When you put it back together excessive sealant shall drip out. The only possible pitfall with a servo is the gearbox, the part above the servo lugs. Open the gearbox carefully with your index and middle fingers while you keep your thumb on the gear that protrudes from the servo. That way the gears will stay in place. Once opened you place a small amount of sealant along the edges of the lid and around the hole for the servo's final gear. Do not fill the lid with sealant as this will force your servo to work much harder, possibly overloading it. Less is more here. Reassemble the servo and you are done.
[B]Receivers
The best way to seal a receiver is by opening it up. When you waterproof the receivers you should have connected the servos and the crystal. Lift up the circuit board and put loads of sealant on both sides. Snap it together and add even more sealant around the servo/battery connectors and the hole for the crystal.
ESCs
Mtroniks ESCs are the easiest solution here as their entire range is guaranteed folly waterproof. Any ESC that you can open up can be waterproofed. Before you fill it with sealant make sure you have programmed it to your liking as the sealant will render it difficult to redo.
Motors
As long as you stay clear of salty water you are safe, dirt is a bigger problem. Most racers actually break in new brushed motors in a glass of water. Extensive driving in water will shorten the lifespan of your motor but, since the threespeeds are so powerful in first gear I do not consider that a problem since the stock motor is very cheap to replace once it throws in the towel. Same goes for batteries, unless you play submarine all day the batteries will survive, but keep them in the dry for as much of the time as possible.
After all wet runs, make sure you re-lube the ball bearings. Extensive driving in water will wash out all grease from the diffs and gearbox, which is good to know.
Depending on how well you succeed you can achieve new depths! Here is a link to a forum post from a Swedish forum showing my F-350 High-Lift driving fully submerged:
http://rsb.se/arena/showthread.php?p=250854
Some servos are sealed, but extremely few are fully waterproof (drown-able) and covered by warranty for such claims. Opening up a servo, receiver or ESC will void the warranty but waterproofing it will eliminate the biggest problem for us driving in the dirt to begin with. For those of you prepared to exchange the warranty for a waterproof model here are my top tips for how:
What do I need?/B]
The easiest way is by using rubber balloons around the servos, receiver and ESC. Sealing the open end with a cable tie (better yet silicone inside the opening and a cable tie) is good for servos and receivers but not for ESCs. The balloons are fragile and even worse, condensation might occur meaning that moist can be built up inside the balloon, making your electronics rust. In other words not the best way to go about it then.
If you want waterproof electronics you will have to open it up and waterproof it. Vaseline (e.g. Chesebrough) works and is widely available. The drawback is that it is not heat stable. If used during a hot summer day or in an ESC it will start to melt, thus diminishing its protective capability.
Silicone is water based and seals great, however it must be allowed to fully dry before anything is switched on. Silicone is conductive before it has dried. A minimum of 24 hours is recommended.
What I recommend is grease from the automotive industry. I personally use Würth WGF130, which is a German product for lubricating wheel bearings. Any garage/shop should have an equivalent product. Wheel bearing grease is the best way to fully waterproof electronics for RC use. It keeps water out, is heat stable (to all temperatures an ESC can generate) and does not lead any current. If you use any other type of grease than Würth WGF130 please do remember to check its lack of conductivity (with a multimeter) before you use it.
There are other products that also work fine, such as PlastiDip and various lacquers. However since all of them are even harder to find and more expensive than wheel bearing grease I will not cover them here.
How do I go about it then?
A toothpick or a matchstick are excellent for applying the sealant. A servo is very easy to open up and seal. Simply remove the four screws in the bottom and carefully remove the plastic bottom cover. Fill the servo with sealant and be extra careful to cover all sides of the hole where the servo lead exits. If your servo housing has an aluminum cooling head or consist of several plastic parts you need to carefully separate them and enter as much sealant as possible. When you put it back together excessive sealant shall drip out. The only possible pitfall with a servo is the gearbox, the part above the servo lugs. Open the gearbox carefully with your index and middle fingers while you keep your thumb on the gear that protrudes from the servo. That way the gears will stay in place. Once opened you place a small amount of sealant along the edges of the lid and around the hole for the servo's final gear. Do not fill the lid with sealant as this will force your servo to work much harder, possibly overloading it. Less is more here. Reassemble the servo and you are done.
[B]Receivers
The best way to seal a receiver is by opening it up. When you waterproof the receivers you should have connected the servos and the crystal. Lift up the circuit board and put loads of sealant on both sides. Snap it together and add even more sealant around the servo/battery connectors and the hole for the crystal.
ESCs
Mtroniks ESCs are the easiest solution here as their entire range is guaranteed folly waterproof. Any ESC that you can open up can be waterproofed. Before you fill it with sealant make sure you have programmed it to your liking as the sealant will render it difficult to redo.
Motors
As long as you stay clear of salty water you are safe, dirt is a bigger problem. Most racers actually break in new brushed motors in a glass of water. Extensive driving in water will shorten the lifespan of your motor but, since the threespeeds are so powerful in first gear I do not consider that a problem since the stock motor is very cheap to replace once it throws in the towel. Same goes for batteries, unless you play submarine all day the batteries will survive, but keep them in the dry for as much of the time as possible.
After all wet runs, make sure you re-lube the ball bearings. Extensive driving in water will wash out all grease from the diffs and gearbox, which is good to know.
Depending on how well you succeed you can achieve new depths! Here is a link to a forum post from a Swedish forum showing my F-350 High-Lift driving fully submerged:
http://rsb.se/arena/showthread.php?p=250854