Hey guys, I got my new Hobbistar out to break the engine in yesterday. When I turn the receiver and radio on the servo controlling the rudder and the nose wheel starts buzzing like its in a bind or something. I move the sevro back and forth and it will stop every once in a while but it buzzes most of the time. It seams to return to center ok but it has me worried.

i have a few that buzz all the time, if its not in a bind then i wouldnt worry,and have fun

The servo is blocked, you are giving input for more movement than and the servo cannot move. My guess would be that this is a throttle servo right?

Blocked ? No it is the rudder nose wheel servo. The throttle servo is fine.

Manks...your post is a perfect example of the biggest problem on this board...

You didnt even really read his post...

He told us what servo is was, the ruuder/nosewheel servo...not the throttle...

He also said it moves freely both ways....its not bound up on something....

does it stop when you put a little pressure on th servo arm?

Some servos will buzz more than others. It's also possible that the nosewheel is not moving completely freely. Try removing the control rod from the servo and moving the wheel back and forth with it. You might feel that it's slightly tight, which could explain the buzzing. If it's tight, it should loosen up with use, but you could try a bit of lube where the nose gear pivots.

I shot a little WD-40 down the guide tubes and that helped a little. Graphite powder would have been better but I couldn't find the 2 tubes I have laying around. I'm not as worried about it since you guys say some just buzz. No big deal now.

Still the same problem, you are not getting enough movement, something is preventing the servo from completing its desired movement. This is not a big deal, but you should play around with the throw rods and see what can be done to give a bit more movement.

aubiecat,
Instead of guessing and playing around with this and that you need to take a logical approach to find the problem. First of all disconnect the pushrods from the servo and see if it still buzzes. If not then the problem is in your linkage or the control surface. If it does still buzz that you have a servo going bad (if this is a non-digital servo it shouldn't buzz at all in the neutral position). Next, reconnect the pushrod to the servo. If it buzzes while it's in the neutral position then there is something about the control surface that is pushing back against the servo, you need to troubleshoot the control surface so that it naturally sits in the center position. Move the servo from side to side. If the servo moves to the end of it's travel and then buzzes the problem is that the servo is trying to push the control surface farther than it can physically travel. You need to reduce the amount of travel that the surface can move. You can do this by adjusting the position of the control rod on either the servo arm or at the control surface. At the servo arm you can move the control rod to inside holes to get less travel, at the control surface move to the outside of the arm for less travel. Adjust the position of the control arm so that you have less throw and this should remove the buzzing when the servo is at the outside range of it's motion.

It was mentioned above that a little buzzing was ok, this is not correct. If these are non-digital servos they should not buzz. The buzzing is caused by either something pushing against the servo when it's centered or by the servo trying to push farther than physically possible. Both of these situations are bad. First off they cause the servo to draw more current from you battery, which will drain your battery quicker. Also, pushing against the limit of travel can damage your servo, your pushrods, or your control surface. Please take the time to troubleshoot the problem and correct it.

Hope this helps

Ken

As always everything RCKen is rock solid correct. I going to add that occasionaly a servo will buzz if the push rods are lifting the servo wheel slightly from the servo. After going through the Ken's list if the buzzing persists try pushing down on the servo wheel without turning it . Sometimes backing the servo screw out a quarter of a turn will solve your problem other times you have to adjust the height of the pushrod.

Ok, I got it fixed.
First the rudder/nose servo was in a bind because of the pushrod going to the wheel. The hole in the firewall was just big enough to slide the guide tube into. Consequently when I moved the servo back and forth the the wheel arm would swing around and make the pushrod slide against the small hole in the firewall. I just took everything apart and drilled a bigger hole. Now the pushrod has plenty of room to move. The wheel turns further than ever.

Second the throttle pushrod was basically snaked like a vine through the guide tube and came out above the engine bracket in an odd position far above the carburetor. I first cut a little notch in the frame closest to the servo to give the tube and pushrod some room. Next I put two 90 degree bends at the carburetor end of the pushrod. I got both pushrods to a point that they would slide back and forth very easy with just a push and pull of my fingers. Now they work perfectly with no buzzing at all.

Now I understand that ARF means Airplane Ready to Fix. I was amazed that it would come from the factory with the pushrods in that shape. I am glad though because I will have a good understanding about how to run servos pushrods when I build my Fourstar.
RC Ken is worth his weight in gold.

A quick kudos for sharing your fix in the beginners zone. Sometimes guys forget to post what worked for them so others can see what advice worked.

One note on the nose wheel. A little movement is plenty, maybe 3/16th to 1/4 inch each way. If you have too much it will make the plane hard to control while it's still on the ground.

I put a few pics on here to show what I did. The one with the throttle pushrod is a bit blurry but you can see the bends I put in the rod. The other just shows the hole I drilled has plenty of room for rod movement.