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-   -   Servo horn hole too big (http://www.rcuniverse.com/forum/tips-techniques-180/11277117-servo-horn-hole-too-big.html)

lennyk 10-26-2012 05:01 PM

Servo horn hole too big
I accidentally enlarged the hole on my nylon servo horn a bit too big, now the 2-56 z-bend is a bit loose.
Unfortunately this servo is glued into a composite wing f5b glider.

Any suggestions on taking up the slop ?



flyinwalenda 10-26-2012 05:16 PM

RE: Servo horn hole too big
I guess you don't want to cut the servo out ?
Can you get a right-angle screw driver in to remove the screw and put a new arm on?
Heat shrink on the rod would probably increase the diameter too much to fit in the hole . Even then it will give way eventually. I don't think there is a good "fix" for this that will last other than to change the arm.

lennyk 10-26-2012 06:04 PM

RE: Servo horn hole too big
I sanded the z-bend, put solder flux and then added some solder to it.

Sanded it down and it is tight now, dunno how long the lead layer will last though but I guess it is better than before.

Charlie P. 10-26-2012 07:33 PM

RE: Servo horn hole too big
Flip the servo horn? Or just buy another horn. Several companies sell arms for various mfg servos.

jester_s1 10-27-2012 06:04 AM

RE: Servo horn hole too big
Lead is harder than plastic, so you should be good to go.

LesUyeda 10-27-2012 06:12 AM

RE: Servo horn hole too big
"Lead is harder than plastic, "

Not really. I would keep a close eye on it.


ARUP 10-27-2012 07:17 AM

RE: Servo horn hole too big
Can you apply soldering iron tip to servo horn to melt the plastic? Push it around while soft to 'tighten' the hole then redrill. Try it on scrap horn first. Or... put a next size up wire with 'Z' bend on it if possible. Or... put a small piece of plactic tube that fits your 'Z' in servo horn after re-drilling to fit. Good luck!

blvdbuzzard 10-27-2012 07:29 AM

RE: Servo horn hole too big
Drill out the hole even more, press fit a piece of brass tubing to reduce the hole size. Solder a piece of brass tube onto the push rod.


karolh 10-27-2012 09:25 AM

RE: Servo horn hole too big
Enlarge the pushrod hole then roughen the inside edges and fill with JB Weld. When dry redrill the hole to fit the pushrod.


KitBuilder 10-28-2012 04:13 PM

RE: Servo horn hole too big
The moral of the story..... fit the pushrod before making a servo inaccesible :) (I;ve been in the same situation... only once though)

karolh 10-28-2012 04:22 PM

RE: Servo horn hole too big
It happens to the best of us ;)


bikerbc 11-08-2012 05:31 PM

RE: Servo horn hole too big
I did that to a whole set of mine not realizing it and then when I started flying the plane it was making this rattling noise that I wasent sure where it was comming from...I finally realized the z bends were loose in the holes...I poked around in my clevises and I found some clips that I think are for L bends..Anyway they clip onto the wire and slide forward and clip on to the L Bend or in this case the Z bend...It takes all the slack out and no more rattle....

tacx 11-08-2012 08:14 PM

RE: Servo horn hole too big
Forget about the z bend and try a nylon clevis. Some nylon clevis's have a large pin.

daveopam 11-09-2012 08:04 AM

RE: Servo horn hole too big
I would put a ball link on it and never worry again. If you have the clearance that is.


combatpigg 11-09-2012 03:22 PM

RE: Servo horn hole too big
It really helps to have a numbered drill index for rigging RC model controls. HF sometimes has them for about $10. The other item is a $20 dial caliper or digital caliper to take accurate measurements of all this tiny stuff we play with.
I sometimes sharpen the end of whatever size pushrod I want to use, then heat it with a propane torch just hot enough to push it through an existing servo arm hole. This has worked for me. I also use a drop of oil after the "Z" bent wire has been installed to prevent the junction between the wire and the servo arm from wearing out.

greenjeep 11-09-2012 07:26 PM

RE: Servo horn hole too big
Use a larger diameter pushrod?

JulieT 11-10-2012 07:39 AM

RE: Servo horn hole too big
<font face="Times New Roman, serif"><font size="3">Depending where the arm is actually located (ability to get to it) :
1. (the better of the two solutions) - take a scrape piece of a servo arm and a flat tip screw driver. place the scrape piece of the arm onto the flat end of the screw driver and heat until the scrap piece starts to melt. Make sure it doesn't catch fire (if using an open flame which should be use as a last resort) and that it doesn't start turning colors (that is, getting burnt). With the z-bend still in the over-size hole, slide the screwdriver in (melted scrap piece up) and flip it over onto where the z-bend meets the over-size hole. Let is cool for a few seconds then move the servo. You might need to repeat until the hole is filled in.
2. Heat up a pair of needle nose pliers and just squeeze the hold smaller.

However if you have the spaceto get to it, I would agree withtacx and use a nylon clevis.</font></font>

dadragon 11-10-2012 09:10 AM

RE: Servo horn hole too big
do you have room to put in a ball link?

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