R/C Naval Combat

Hi all,

Just wondering if anybody has used these before, they are the Futaba s3014 Waterproof servo: http://www.howesmodels.co.uk/RadioControl/viewProduct.php?ProdID=1354

I actually saw them in the magazine "Model Boats" from the UK and went to this site to see what they were.

I went to the Futaba main site but coudln't seem to find them.

It is not waterproof... it, like most futaba servos is "water resistant" (e.g. splash resistant). If you want a waterproof servo you will have to do it yourself.

I thought it might be something like that. Up here we use tool dip to waterproof our servo's and receivers.That way you don't need a bulky waterproof box. I just thought I'd ask about those servo's as if they were truly waterproof it would save some hassle.

I use electronics safe silicon to coat the servo in (I have seen some corrosion from the tool dip method, I think solvent related) and then use an O-ring on the servo output shaft that is kept well greased with waterproof white lithium grease.

I reapply the grease before each day of battling and have never had any trouble...

IMHO there is no such thing as a "waterproof" servo, only "water resistant" servos. At my pond, I have seen many different attempts to protect servos, from watertight boxes to tooldip and o-ring, to individually coating each circuitboard with CA glue. All of them have been sunk, and all of them have failed. The only "success" I have seen was an unarmed merchant ship that had foam blocks on deck, and when sunk would only sit a few inches below the surface. The rudder servo on that was sealed using the o-ring and tooldip method, and held up fine until the foam cargo blocks were replaced with saltine and triscuit crackers.

I guess it all depends on what depth of water you sink in. More than a few feet down and just about every method fails. I just drill a few holes in the cases of my servos, so the water drains out quickly and I can flush it with alcohol without any hassle.

Hi Carl

I'm interested in the method you described that you use.I've heard of people doing it but never really understood how effective it was. Do you waterproof anything in the servo or just drill a few holes in the bottom of the case and flush with alcohol after a sink. Does this method affect the life of the servo?(more corrosion etc...)

Scott

This method is based on the fact that waterproofing serves to prevent water from getting in, and ALSO has the undesireable side effect of trapping any water that squeezes through and making it more difficult to clear out with alcohol. The goal is to provide sufficient protection until the ship is already sunk, then provide easy access to clean and dry the servo using rubbing alcohol. The first step is to drill two holes in the bottom of the servo case to allow you to easily pour in the alcohol and allow it to pour out and evaporate. If you want, you can cover the holes with tape of some sort to provide better splash protection.

I always recommend using the cheapest servo that will work. Don't use a $50 metal gear micro servos if a $10 standard servo will do the trick. When something goes wrong, it is much easier to replace. Make sure you have easy access to your servos. I only need to remove one nut and the horn of one servo before I have complete access to all my servos. After a season of hard battling with plenty of sinks, servos will slow down and will need to be replaced. I believe this is due to using Corrosion-X (which leaves a protective coating that may slow down the servo) rather than rubbing alcohol or WD-40, though I haven't done a thorough investigation.

I can attest to the silicon-O-ring method, if done correctly with two examples.

My karlsruhe, 10 feet down for more than an hour, all servos ok.

One of my buddies Kirishima's, 20 feet under water, 5 days, only servo that survived was the only one that was coated on the outside with silicon and had the O-ring on the spline.

the trick is to relube the o-ring often. that is what most people forget about, if you don't keep the O-ring lubed, the case fills with water.

I use a dielectric silicone based spray on my servo boards, and have large holes top and bottom in the cases. I've never had a servo fail from water damage. They glitch when the pots go under, but a good soaking in methylated spirits (alcohol) and a blast of air soon sets them to rights.

I believe there is one way to water prof a servo like that... i think all you do is put a small thin rubber band around the space that seperates the serco arm from the servo motor....

And that, pew pew, would be a non-effective way. Without grease there and sealing around the rather poor fitting o-rings elsewhere on the case, the water always gets in...

quote:

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Originally posted by Kotori87

IMHO there is no such thing as a "waterproof" servo, only "water resistant" servos. At my pond, I have seen many different attempts to protect servos, from watertight boxes to tooldip and o-ring, to individually coating each circuitboard with CA glue. All of them have been sunk, and all of them have failed. The only "success" I have seen was an unarmed merchant ship that had foam blocks on deck, and when sunk would only sit a few inches below the surface. The rudder servo on that was sealed using the o-ring and tooldip method, and held up fine until the foam cargo blocks were replaced with saltine and triscuit crackers.

I guess it all depends on what depth of water you sink in. More than a few feet down and just about every method fails. I just drill a few holes in the cases of my servos, so the water drains out quickly and I can flush it with alcohol without any hassle.

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A couple of variations:

Coat the circuit board with Scotchkote.
Use Scotchkote instead of tooldip on the seams and screw heads.
Add a little extre grease to the spline shaft before seating the O-ring, then grease the O-ring as well.

Found this today looking for waterproofing:

http://www.societyofrobots.com/actuators_waterproof_servo.shtml

Site is really great!

Enjoy!

Interesting how that person filled the servos with oil. Fill the servo with oil, add an o-ring, and then cover with Skotchkote, and you may have a decently waterproof servo. I'd want to have some way of easily refilling the oil every battle or so, but there are ways to do that.

The person in that article used mineral oil. Where can you get this mineral oil stuff? And what other oils would be suited for filling a servo?

Use mineral oil. Google it to find a nearby supplier. Check out the video, it explains a lot.
I would do only one thing different. Instead of filling it up and then trying to assemble it (very messy), just drill two small holes in the top of the casing. Assemble it and fill it up using one of the holes. Then seal up the holes with the RTV.

I wonder if generic cooking oil would work. I've got some of that around the house, and a few old junker servos, too...

That should work, a year or so ago Tom's Hardware built a PC that was immersed in cooking oil for cooling(they took all the fans out), they built a special case and filled it with a few gallons of oil. It was a high end system with a beefy CPU and graphics card and the system did fine with just the passive cooling from the oil. So i don't see why it wouldn't work with our servos, but then again just coating the innards with epoxy or scotchkote works really well too.

I found the article so here it is.
Visit this site

The issue as I understand it is the Pot will die after a period of time. This is a great article you found throat! [:)]
I will encase a servo in exopy and drill two small holes in the top, one to fill with a syringe and the other to let the air escape. Then I will seal both holes with RTV. The oil will also lubricate the o-ring.
This has me totally excited (I really need to get out more) and will do the test this weekend.

Here's another cool video by a different company.

http://www.engadget.com/2007/05/12/puget-custom-computers-mineral-oil-cooled-pc/

I wonder how well RTV will hold at 8-10 feet deep, like at my battle pond. I know it didn't hold water out of my ROV at 40 feet under the surface of the Neutral Buoyancy Lab. On the other hand, it's often used for sealing fish tanks, so it works in shallow depths. I'm sure there will be plenty of volunteers to help you test the water-proofing of your ship, so the main question is how deep do you plan to get sunk?