Hi, this is Wayne again with a topic “Maker Hangar: Episode 5 – Servos”.
Hello and welcome to maker hanger, my name is Lukas weekly and today we’re going to be talking about servos, we’ll take a look at how they work, how they’re classified and how to hook them up to the control surfaces on your plane. So let’s get started so servos are made up of small brushed motors a potentiometer and a couple of gears. The potentiometer regulates the movement of the motor and allows the servo to move exact amount of degrees. A servo can move 180 degrees mechanically, but under its own power it can only move 90 degrees. If you take out the pot and replace it with a fixed resistor, then you have a continuously rotating servo.
There are two main types of servos analog and digital they’re. Both the same with all the physical parts, the potentiometer, the gearing and the brushed motor, except for the digital servos, have a microprocessor that takes in the input from the receiver. This allows them to be more accurate and faster because of this they do take up more power. However, it’s not going to be very significant in the plane.
We’Re going to be building the next set of classifications is if a servo is either metal or nylon geared yep, you guessed it. This just means the gears inside of the motor are either metal or nylon and obviously metal gear. Servos are much stronger and they don’t strip as easily the next classification is white and 9 grams servos are the most common because they’re used in foam airplanes. There are also several other types of servers that are categorized by weight and size.
9 grams are considered micro servos. There are also sub micro and standard sized servos. There are a couple other types, but you’ll probably only deal with micro servos.
When building film planes, then voltage is a factor. Most servos run off of 3 to 5 volts, but some high voltage servos run off from seven point four or a 2s lipo pack, and these are for larger planes that require more torque and the last classification is torque. You shouldn’t really have to worry about this, because when building a foam airplane any small servo will be able to push and pull a control surface and metal geared servos will be good for almost any application.
Now, let’s talk about linkages and there’s a couple parts you’re going to need: first, the servo arm the push rod and the control horn. The servo arm obviously goes on the servo. The control arm goes on the control surface and then the push rod spans the gap in between these two and allows the servo to push and pull the control surface. There are different types of attachment methods for the control, horn and servo arm sides, the Z Ben the Elven, which requires an extra piece of snap-on and lock it in place the clevis and the screw lock.
Any of these can be combined on either end of the push rod to secure it in place, but the simplest is 2z pins. This requires no extra hardware. If you connect this linkage to the top of the servo arm and to the bottom of the control horn, then you’re going to get a large amount of movement with low resolution. And if you connect the linkage to the bottom part of the servo arm and the top of the control horn, then you’re going to have small movements with high resolution I’ll explain how to hook up the control surfaces when we start building the plane. In a later episode now, let’s talk about servo placement: servos can be mounted flat with their arms pointed away from the mounting surface, but can also be embedded inside of the plane with the arms. Parallel to the mounting surface, you can mechanically reverse a servo by flipping it or changing out the linkage.
Let me show you, okay, so here’s our servo and pretend that the tables are winged and we glued the server to the outside of the wing. Well, we can take our push, rod again, put it in, and so when I pull back on the stick you can see the servo arm is coming at me. Well, if I flip around the servo, take off the arm and flip it over turn around arm and put it back in when I pull back at me, it’s going away, so that’s a way that you can mechanically reverse a serve off by flipping it now, if We flip it this way so take it off and flip it this way and put it back on, and I pull back it’s still going away from me. So the only way you can reverse the servo by flipping it is by this way. This is easier to see on a server, that’s embedded in the foam with a double arm. So if we put in the push rod to one of the holes, I’m going to push the stick to the left, so it’s going away from me right! Well, if I take out the push rod and put it in the other hole, I push it to the left.
Now it’s coming at me, so this is another way that you can mechanically reverse a servo without having to go into your radio having all your control surfaces hooked up, isn’t any good if you can’t control them and that’s the job of the transmitter. So, there’s a lot to go over with how to program it and set it up so I’ll talk about that next time, thanks for watching .