crebulus

I have the Hangar 9 Mustang PTS. I put a servo in for the flaps. It works great, but it makes a buzzing sound after it stops. I know this can't be right. My throttle servo did it at first, but all I have to to is move it one click and it stops. Any ideas how I can fix this? I've already adjusted the travel settings on the radio, and it'll stop until I activate the flaps again.

Rodney

Several things can cause this. Most often it is because the servo wants to move the flaps farther than they can be phyically moved. If so you need to move the attach point on the servo arm closer to the pivot point at the servo end or move the attach point on the flap horn farther out. It could also be caused by a bad hinge binding up or by bad hinge alignment. If your transmitter allowes EPA (end point adjustment) you can also dial out any overtravel there. Have one of your local experts give you a hand or take it to a knowlegable hobby shop attendant.

w8ye

My Feedback: (16)

Servos making noise like that draw a lot more current from your battery. You flight time on your battry will be rapidly deminished. The servo will wear itself out sooner.

You need to do as Rodney has recommended.

Enjoy,

Jim

crebulus

I adjusted the travel and some other things, and the noise stops after a few seconds. Is this normal? I will talk to the guys at my field next time I take it to fly.

w8ye

My Feedback: (16)

Ideally there should be no noise except the initial index when you turn the receiver on?

Enjoy,

Jim

multiflyer

Servos vary widely in design. Different motor control characteristics as servo approaches commanded position. Different quality internal potentiometer for sensing position. Some servos are just very cheep and don't drive themselves to or detect when they are at the commanded position very well. If the surface hinging or linkage has excessive movement friction, poor servo will buzz nearly constantly. If adjusting throw properly does not fix, then check how cheep and how worn out your servo is, and try another one?

Multiflyer

exeter_acres

My Feedback: (2)

just to toss this into the mix....

Which Servo...
is it by chance a digital servo?

as others mentioned buzzing on a standard is bad... means it is fighting something somewhere....
but buzzing on a digital servo is normal.....it is the servo continually trying to center itself.... or hold its position

kolban

I am a 3 week newbie ... I bought a Hobbico Superstar 40 which has 4 Futaba S3003 servos. At least 2 of these have a pretty constant 'buzz' associated with them at neutral settings.

exeter_acres

My Feedback: (2)

since 3003's are standard....the buzzing means there is some binding somwhere.....

unhook the control rods from the servo, do they move easily? does the control surface move easily...

buzzing = binding = high current draw on battery = bad

crebulus

All the servos in my plane are jr 537. The noise it makes does sound like it is trying to get somewhere, but can't. After I adjusted the throws, it only buzzes for a few seconds, then stops. I tried everything I could think of, and could not get it to not buzz. It doesn't buzz at all when nothing is attached.

w8ye

My Feedback: (16)

The old Hitec HS300's would sometimes hunt, They couldn't decide just where neutral was? But buzzing is trying to be somewhere it cannot get to. They can buzz at near the neutral position.

A standard servo does not have much torque when it is just a short distance from where it wants to be. (Like neutral). If the controlled surface is stiff, the servo will buzz.

Enjoy,

Jim

Johan_nl

Hi,

Been reading this thread with interest!

I'm just finishing building a SIG Kadet MkII and my servo's only buzz at the extreme throws. I believe they are buzzing to keep the control surface in place as I think the hinges are pushing back a bit, it's definitely not that the control rods are obstructed.
Would you estimate that to be a problem? In neutral poisition and when moving there's no buzzing, just a slight bit at the ends....

Thnks.

J.

MannyEdge

My Feedback: (9)

My servos do the same thing at extreme end points. What is the fartherest you can do for end points. I have a SSE and I know you want the most throw for the rudder, but I think 140% of end point might be too much.

shd3920

I use the S3004 ball-bearing servos with my Futaba 4EX computer radio and at the start I had buzzing in the throttle and rudder/nosegear servos of my LT-40. I have fixed the buzzing in both the throttle and rudder servo rods by changing hookups and such, but the nosegear rod still makes the servo buzz when it is fully extended but stops when it is at rest. I have done everything I can to avoid the buzzing (changing connections, moving the connections to different servo holes, pulling out the pushrod tube glued into the fuselage and replacing it, cutting the tube shorter and using longer steel rods). Finally after the latter was done the buzzing has quieted considerably but will still buzz at full extension for a few seconds. I don't know if ball-bearing servos commonly buzz but I have accepted the way it is, all rods move smoothly and do not bind so with it only being the nosegear that sometimes buzz I was told it won't really interfere with the flying, but to next time test the rods before permanently gluing the pushrod tubes in place.

I have never made pushrods out of wood dowels before but the next model I build (the Mini Telemaster) I will be doing just that.

Me telling you this probably won't help with your problem of the buzzing but I just wanted to share my 2-cents worth.


~Steve~

bruce88123

Instead of setting at 140%, you should change your mechanical setup. Use longer servo arms or move the pushrods into a different hole on the control horns. Most radio mfg will tell you this in their manuals. Using 140% is just asking for trouble. To me it's a sign of a poor installation.

MannyEdge

My Feedback: (9)

Hey you know what Bruce, I did all that and it was not poor installation. Instead of criticizing people you should help them. I do not come here to get criticized. Why dont you do it some place else. I come here to learn from other people in the hobby I love.

bubbagates

My Feedback: (32)

Alright folks, I'm gonna toss in my experience in regards to the servo end point part of this discussion in regards to JR and Hitec servos. All of my experience is in the JR and Hitec lines so I really cannot say much about Futaba other than what I have read. I am also not siding with anyone on this subject. It is just practical experience. I have used what I am about to describe in 40 size planes with non-digital servos up to my 1/3 scale planes with digital servos

After a few emails between myself and Danny Snyder of JR, JR recommends the TX end points be set at 140%. From that point then a one to one mechanical advantage can be achived by using the correct servo arm length with the arm at 90 degrees to the servos centerline, control horn length (which ideally would be the same length as the servo arm) and control rod length. If you can accomplish this you will end up with a very tight linkage with virtually no slop and you will maintain the maximum torque the servo can provide across it's full range of travel.

The hard part is getting the servo arm length to match the control arm length. Now to be a little more clear on this, when I say length, I am referring to the points on both where the control rod is connected. So, on the servo, if you measure from the center of the servo arm screw hole (the screw that holds the arm to the servo) out to the center of the hole on the arm where the control rod is connected and then you measure the control arm on the flying surface from where the arm mounts to the surface out to the hole where the control rod is attached and both measurements are equal you now have a one to one mechanical linkage.

This is very important on larger/heavier planes and for all planes it helps reduce one of the major causes of flutter. Actually flutter is caused by many things all coming together at the same time, but a solid control setup helps allot with eliminating this.

It is not that important on the smaller planes but if you really want to have a plane that flies as well as it it, this will certainly help.

Let the flaming begin...

bruce88123

Based on the previous post I am willing to retract my post of "poor imstallation". However, you will still not find such a setup in my planes. Still doesn't seem right to me. Again, this is MY opinion.

If 140% is to be considered normal, then why not make that amount 100% and deviate from there?

Rodney

What really limits the amount of throw you can safely use is the internal design of the servo itself. The feedback potentiometer is the deciding factor. Where the connections to the end points on the potentiometers resistive element determins how far you dare turn the potentiometer before it gets into an area where it either binds up or fails to uniformly vary the resistance. As long as the resistance change is constant and not mechanically binding, there is no degredation of the reponse.

shakes268

It also helps reduce gear wear. If you use a low ATV (100% and below) and use servo arms that are very long to get the desired throw the servo is always traversing over the same set of gears for small corrections to full throw. These gears will wear from being used so much. However, if you increase the ATV and use the correct servo arm length you optimize the usage of the servo's resolution and the servo actually moves more to obtain the correct throw. With higher ATV, more gears are traversed in a single operation reducing wear (you're not ALWAYS using the same 5 gears for everything). So I agree with you..in a sense, I am using more like 120 on my end points to give myself room for adjustment instead of the 140 but I may try to set things up at 140 since JR recommends it.

bubbagates

My Feedback: (32)

On the JR 8611 series and some say the 8411's as well, you must using 150%. Personally I have always used 140% and have never had a problem.

I never gave gear wear a thought when it comes to resolution.

shakes268

Futaba radios, at least the 9C max out at 140% for adjustable end points. At least thats as high as I can get my 8611's to go.

MannyEdge

My Feedback: (9)

I did not think I had a bad installation. Thanks Bubbagates for clarifying the issue.

RCKen

My Feedback: (9)

Ok, I've been watching this thread for a little bit and there seems to be a little confusion going on in here. The original question was about hearing "buzzing" when the servo is at the limits of travel. Looking at the servo and the servo alone (no computer mixes or adjustments involved) having a buzz in your servo is not good. This is caused because the servo is still trying to push (or pull) against something that cannot physically move any longer. That is what the "buzzing" sound comes from, the servo motors still trying to move. This servo buzzing isn't a good thing either. First of all it draws more current from you battery, and secondly it can damage the electronic and mechanical parts inside of the servo. Ok, no matter what kind of settings you have in your radio or what you can do with that radio, if your servos buzz at the ends of the travel then they are not properly set up or installed.

Ok, if you have buzzing in your servos you need to remove whatever is causing that buzz. In this case we are talking about a buzz at the end of the servo travel. I'm still talking on a purely mechanical level (meaning we're not going to worry about radio settings just yet). It's really pretty easy to talk about. If your servo buzzes at the end of the travel, then your servo is trying to push the control too far (or in other words the travel of the control is shorter than the travel of the servo). So we need to do a mechanical adjustment. Since the original questions was talking about a flap servo, so it's a pretty much given that we can't make any changes in the control surface itself (hey, the flaps can only go so low right?? . Since we can't change the amount the control moves, then we need to look at change how the linkages connect to the control surface and the servo. Most control horns and servo arms have several holes in them so that you can make adjustments such as these. At the control surface end, moving the control linkage to a hole further away from the control surface will cause the surface to move less. At the servo end of the control linkage it is just the opposite, moving the linkage to a hole closer to the center of the servo arm causes the control surface to move less. (see the attached diagrams for an illustration of what I am talking about). You can play around with how you position the linkage on both the servo arm and the control horn at the control surace until you come up with an arraingement that has less travel, and therefor stops moving the servo before the physical limit of the control surface is reached. There is one more adjustment that can be used that could help in the this situation. Change the starting and stopping point of the servo itself. This is fairly easy to do by simply removing the screw from the center of the servo, lifting the servo arm off the servo, rotating it one click in to a new position on the servo, replace the servo arm on the servo, and the replacing the screw. What this will do is physically change where that control surface stops at. Make this adjustment until the servo can move freely throughout it's range of motion without being physically stopped by limits of the control surface.

Ok, now let's add in radios to the mix. Or more specifically, computer radios. Computer radios have been a great tool in getting a plane adjusted out. Although the computer radios make it easy to make corrections like this it's still very important to get your plane as close to mechanically correct before you start making any changes with the radio. But in our sitution here we are looking at the buzzing caused by the servo trying to move past the physical limits of the control surface. Using the radio to do this is very easy to adjust using End Point Adjustment (EPA). With EPA you can use the radio to adjust where the end of that servo's movement will be. It's a simple matter of changing the EPA for that servo until the end of the servo's travel matches the end of the physical travel of the control surface. It only take a few seconds to correct this issue by changing the EPA.

Now it took me some time to figure out what Bubbagates and the others were talking about by setting the EPA's of your radio at 140%. What they are saying is that the servo will have it's best performance if you set the EPA's at 140%, but that doesn't mean that you can set it to 140% in all of the possible applications. That's kind of like saying that your automobile can drive 120 mph, so you can drive that speed everywhere you go. Of course you can't do that. On different roads and road conditions you have to adjust your speed according to where you are driving, i.e. you have to drive slower on a bumpy gravel road than you can drive on the highway. There is no difference with your radio here. Yes, they may say that you should set your EPA's to 140% but that is a guideline and you may have to change that figure to fit your exact installation. If you have your radio set at that and the servo/control surface can't physically travel that distance then you are going to have to change the setting in your radio. By all means you should try to follow the radio manufacturer's recommendations whenever possible, but even they will tell you that you will need to make adjustments according to your situation.

There has been a lot of information put out here so far, but to break it down to the basics of the situation. A servo buzzing for any reason is not a good thing. If you have a servo buzzing at the end of it's travel then you are trying to push that servo too far and adjustments need to be made to it. Whether those adjustments are made mechanically or with the radio will be up to each individual to determine what's best for them, but those adjustments need to be made.

Ken

cdale03

I understand the end point travel adjustment to stop servo's from buzzing but , I have a few that buzz at neutral, I can giggle the stick a little and it will stop but the next time the servo moves it s back,

How do you adjust that out?
Stand servo's Hitec and JR brand.

Thanks.