1. I am trying to find a good servo to move my rudder. It's a going to be a pretty normal sized rudder, what would you say would be a safe torque rating to go with? 2. This may sound like a stupid question, but I have been looking over all the threads here and I can't figure out how the rudder goes through the hull. I understand how you can use gears etc. inside the hull, but how does the servo arm get outside without having a big arc being cut in the hull? 3. I am making my own rudder, my plan is to make the rough shape out of wood, sand it down to get the curves and then put a layer of fiberglass over it. Does that sound right? 4. Totally unrelated to the rudder questions, but I am going to build a simple mag switch to control my guns and my props. About how much torque does it take to press a small push button? Just a ballpark figure? Thanks!
The ruder shaft goes thru the bottom of the hull thru a sleeve and the servo connection is inside the ship there are many ways to turn ruder here is how I did my liberty ship
So there is only one point that the rudder connects to the servo, instead of attaching twice? Ok, that was part of my problem them, I thought the servo arm had to attach twice.
Meta, the belt drive that Monkey did is one (very cool way) to do it, there are many. Some people buy a gear that fits on the servo, and gears that fit on the rudder shafts, and put the whole assembly together that way. Some just use an arm on the rudder shaft, with a pushrod to the servo arm. For big ships with one rudder, I use two pushrods, one on each end of the servo arm. The belt drive method seen above can also drive two rudders very nicely. Which you use depends on budget and technical skills I just have the arms and pushrods sitting around, so I use them
Meta here is where I got the gears and chain from they even thru in some tootsie rolls http://www.servocity.com/html/mechanicals___accessories.html
Yes, that website is the one I hope to buy my whole radio package from, I actually found it in one of your other posts Free candy is a bonus I am in high school still, so anything helps to make me feel like I'm spending less money, even free sweets
http://bp2.blogger.com/_iPCa2wo2FlY/RlDL4sIafKI/AAAAAAAAAF0/JnCU4xi8Y1c/s1600-h/runninghdw.jpg That is one way. Although a word of warning: Most servos are flexible enough that to properly tension that small a belt is almost impossible (My prop wash in that setup could sometimes snap the rudders to the next tooth over). So I went back to gears. With a larger pulley, however (or a belt with bigger teeth) that would not be a problem. I will try to find a picture of my tirpitz's newer gear drive.
That is actually a chain I was concerned about that till I abused it for six batteries and I tried to jump it in my pool with no luck so I think I should be okay but one never knows
Ok, I think I will probably either directly mount it on the servo or use a simple geared set up. What about the torque, how much torque does it require to move a medium sized rudder, and what about the mag switch servo?
the mag switch servo can be any servo; I've used the little micro ones that came with my Spektrum radio for the mag throttle switches. For the rudder, what size ship are you building?
I'm not strictly into RC combat yet, I'd like to do it someday but I want to master the basics without the historical accuracy restrictions, etc. My ship is 33 inches long, 8 inches wide with a fiberglass hull and plywood innards, if that helps.
An ordinary servo is quite capable of turning any but the most enormous rudder, at the speeds we sail. As for torque required to operate mag switches, it all depends on the springs in the switches and the length of your servo arms. Once again, almost any servo should operate your mag switches easily.
For high-speed boats, sometimes you need a heavy-duty servo because of the force on the rudder. At scale model & combat speeds, that's not an issue. Any decent-quality standard servo will be more than good enough, & I wouldn't worry about any problem with a mini or micro, if you need to save space (those are usually more expensive, though). Good-enough standard servos can be found for about $10 or less. Powder Monkey: If you reverse your servo to get the sprocket closer to the rudder, you'll shorten the chain. A long span of chain like in your photo makes it more likely to jump. Also, the relative sizes of your sprockets are going to give you a lot of over-throw of the rudder. Anything more than about 30 degrees & instead of turning force it's going to act like a brake. If that's what you want to do, fine, but hard rudder is going to stop you more than turn you. As set up, you'll get max. turning at about 1/3 rudder, maybe less. JM
I found some shafts devices that just clamp onto the servo, is there any reason why I couldn't just turn the servo upside down in the back, have the shaft go out through a bushing and attach the rudder directly to that?
JM I have been unable to force it to jump sit down or other wise roll over off of the sprocket and seeing as it is my 9 year olds boat I like the brake option [] however I do have another gear to change it to that doesn’t throw as much once he learns the flow and ebb of things I think my fellow captains on the water will appreciate it as well LOL
The biggest reason is space between the top of the rudder stuffing tube & the underside of the deck. Also, allow for any coupling that you'll need between shaft & servo. You might find a low-profile servo that fits, but a standard size won't fit very many ships. JM
If you do need to use a high-torque servo, I had some good fortune to find that my hobby store had some used and 'scratch&dent' parts for sale cheap. I've since seen this in other hobby stores, too.
