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Old Jan 18, 2012, 10:30 AM
Walkera fan-boi
MiniChopper4Me's Avatar
USA, FL, Sunny Isles Beach
Joined Jun 2009
166 Posts
Mini-Review
Xtreme Productions Metal Servo Horn for Walkera servos

A couple of weeks ago while rebuilding a newly purchased Walkera heli (the V120D02S), I was working on doing the mechanical setup of the servos and trying to achieve, as is recommended, a 90 degree setup at midstick. Unfortunately, with the provided servo horns, I was unable to come even relatively close which made me look to see if there was a way to get a variety of servo horns so as to find ones that came much closer to 90 degrees at midstick.

I had come across Xtreme Productions' Metal Servo Horn for Walkera servos. Although they are not super cheap, the option of paying roughly $6 per servo horn still comes out cheaper than buying sets of replacement servos at over $30 a set just to have more servo horns to use for mechanical setup.

Before spending any money on them, however, I wanted to be sure that there were variances built in to the "rotation" of the horn so that one could actually have different horns to sort through and find one that best suits the given servo.

For those who don't understand what I mean, I'll clarify. A Walkera servo has a gear where the horn mounts that has 20 teeth on it. Given a circle has 360 degrees, the angle between each of the teeth is 18 degrees. If the position you need the servo horn to sit at is at 9 degrees from top dead center and both the servo horn and the servo have their top-most gear tooth at top dead center, you'll be off by 9 degrees. However, if the servo horns have their "top tooth" off by different degrees clockwise and counter-clockwise from top dead center by different amounts, you'll be able to narrow down that margin.

Ideally, you'd make 17 different servo horns, ranging from +9 to -8 degrees from TDC, and you would be able match a servo horn to a servo with a 1 degree margin of error. This, however, is unrealistic I think. Maybe 3 different orientations, -6, 0 and +6 degrees would be good, reducing the margin of error to +/- 3 degrees.

I received 3 metal horns from Xtreme Productions in an effort to figure out whether or not they were being manufactured with different orientations, or if they were simply made in one orientation. I am happy to report that at least of the 3 I received, there are 2 different orientations. The horns are also well made, with 4 different holes for mounting the ball link, more than their plastic stock counterparts come with (I'm pretty sure the stock ones only have 3 holes). It comes with a brass ball link that does not have any slit for screwing it in, but shouldn't pose a problem to assemble. The ball link clearly needs to be mounted using blue loctite to avoid it vibrating loose. The easiest thing to surmise about these is that they will withstand much more abuse than the plastic version will.

I've included some photos of the product, in case anyone is interested!

Charlie
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Last edited by MiniChopper4Me; Jan 18, 2012 at 10:34 AM. Reason: Typo
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Old Jan 18, 2012, 10:49 AM
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chevell's Avatar
USA, CA, San Diego
Joined Oct 2007
762 Posts
It looks like these will allow for some tuning/geometry improvments at a slight weight disadvantage. Most likely they would also be unbreakable.

I think the S version also uses a slightly larger size link/ball set up, so the old style plastic link ends might be required for the S version.

I have good luck using the Xtreme parts.
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Old Jan 18, 2012, 11:27 AM
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United States, MA, Springfield
Joined Dec 2010
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this might solve a minor issue but creates a bigger one... faster stripping servos.
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Old Jan 18, 2012, 11:28 AM
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Joined Dec 2007
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Quote:
Originally Posted by MiniChopper4Me View Post
A couple of weeks ago while rebuilding a newly purchased Walkera heli (the V120D02S), I was working on doing the mechanical setup of the servos and trying to achieve, as is recommended, a 90 degree setup at midstick. Unfortunately, with the provided servo horns, I was unable to come even relatively close which made me look to see if there was a way to get a variety of servo horns so as to find ones that came much closer to 90 degrees at midstick.

I had come across Xtreme Productions' Metal Servo Horn for Walkera servos. Although they are not super cheap, the option of paying roughly $6 per servo horn still comes out cheaper than buying sets of replacement servos at over $30 a set just to have more servo horns to use for mechanical setup.

Before spending any money on them, however, I wanted to be sure that there were variances built in to the "rotation" of the horn so that one could actually have different horns to sort through and find one that best suits the given servo.

For those who don't understand what I mean, I'll clarify. A Walkera servo has a gear where the horn mounts that has 20 teeth on it. Given a circle has 360 degrees, the angle between each of the teeth is 18 degrees. If the position you need the servo horn to sit at is at 9 degrees from top dead center and both the servo horn and the servo have their top-most gear tooth at top dead center, you'll be off by 9 degrees. However, if the servo horns have their "top tooth" off by different degrees clockwise and counter-clockwise from top dead center by different amounts, you'll be able to narrow down that margin.

Ideally, you'd make 17 different servo horns, ranging from +9 to -8 degrees from TDC, and you would be able match a servo horn to a servo with a 1 degree margin of error. This, however, is unrealistic I think. Maybe 3 different orientations, -6, 0 and +6 degrees would be good, reducing the margin of error to +/- 3 degrees.

I received 3 metal horns from Xtreme Productions in an effort to figure out whether or not they were being manufactured with different orientations, or if they were simply made in one orientation. I am happy to report that at least of the 3 I received, there are 2 different orientations. The horns are also well made, with 4 different holes for mounting the ball link, more than their plastic stock counterparts come with (I'm pretty sure the stock ones only have 3 holes). It comes with a brass ball link that does not have any slit for screwing it in, but shouldn't pose a problem to assemble. The ball link clearly needs to be mounted using blue loctite to avoid it vibrating loose. The easiest thing to surmise about these is that they will withstand much more abuse than the plastic version will.

I've included some photos of the product, in case anyone is interested!

Charlie
What transmitter are you using? Modern day computer TX's adjust the variation at the servo using the subtrim menu so it doesn't matter if the servo horn doesn't mechanically fit at exactly 90 degrees. Just use subtrim to make it perfect. Of course this assumes you own a Walkera 2801 Or Devo TX
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Old Jan 18, 2012, 01:25 PM
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MiniChopper4Me's Avatar
USA, FL, Sunny Isles Beach
Joined Jun 2009
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Quote:
Originally Posted by Xrayted View Post
What transmitter are you using? Modern day computer TX's adjust the variation at the servo using the subtrim menu so it doesn't matter if the servo horn doesn't mechanically fit at exactly 90 degrees. Just use subtrim to make it perfect. Of course this assumes you own a Walkera 2801 Or Devo TX
Thanks for pointing this out Xrayted. I do own and use a 2801 Pro v2.3 for my Walkeras, and use the subtrim to finish any detailing necessary. I like to avoid it as much as possible for a couple of reasons:
1) Walkera doesn't allow you for the most part to do this on an individual servo basis. The mixing takes place at the receiver on all of the newer helis, and that means you have to do complex subtrimming to get the desired result because each adjustment corresponds to multiple servos moving. Its always been much easier on the DSM family of TX and RXs, where you can adjust the servos individually (elevator, aileron, pitch).
2) I would almost swear that I read somewhere to avoid using subtrim on the newer 3 axis gyro models.
3) The fewer the changes you've made to your settings, the less you have to remember when setting it up again, and less to pass on to the new owner when that time comes. Call me OCD, but I like keeping it simple.

You are in the end, however, completely right.
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Old Jan 18, 2012, 01:29 PM
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Arivaca,Arizona
Joined May 2008
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It's just metal bling and extra weight. Can' say I have EVER broken a servo horn. Swapping horns between servos may give a better mechanical alignment.
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Old Jan 18, 2012, 01:43 PM
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USA, CA, San Diego
Joined Oct 2007
762 Posts
Subtrim shouldn't be an option when using one servo mode. All adjustments should be done mechanically other than total pitch travel and end points.
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Old Jan 18, 2012, 01:50 PM
Walkera fan-boi
MiniChopper4Me's Avatar
USA, FL, Sunny Isles Beach
Joined Jun 2009
166 Posts
I was curious about the weight, flex and such over the stock version myself, but don't have access to my scale and calipers until I get home. I'll include that data as soon as I can collect it later today.

As far as swapping the horns between servos, I can tell you that on the V120D02S I was working on two weeks ago, I was unable to get them any better. As far as breaking horns go, I've only broken one once, but had the ball link strip the plastic hole and pop out more than once. Its still cheaper to buy one of these metal horns than buy a replacement servo for the plastic horn. You can't get the plastic ones by themselves.

Charlie
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Old Jan 19, 2012, 05:24 AM
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Tokyo
Joined Jan 2010
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I want rubber horns that will give in a crash.
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Old Jul 15, 2014, 01:45 PM
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Joined Jul 2007
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I know the thread is old, but what the heck. I just bought a used Master CP, all 3 servo arms are split open, any idea if these will fit. Do all Walkera servos use the 20 tooth output shaft (I have several Walkera helis, it would be good to know this for future reference).
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Last edited by ChargedDust; Jul 15, 2014 at 03:10 PM.
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Old Jul 18, 2014, 10:11 AM
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Tucson, Az
Joined Feb 2007
7,662 Posts
If Master has stock servos. change them to WK7-6-9's. Futaba S3114's fit also/ same with hi-tech HS-5055's. HS-5055's need to be reversed, hi ti-tech has servo reverder. DO NOT reverse servos from TX. It will mess up gyro.
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Old Jul 20, 2014, 03:31 AM
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Joined Jul 2007
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P.O. upgraded servos to WK7.6-9, will any other MFG servo arms fit...?
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Old Jul 23, 2014, 01:44 AM
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United Kingdom
Joined Sep 2013
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Metal horns = no servo saver mod = lots of striped servos = waist of money - plus its heavier

It is not easy to adjust stock servos mechanically but not impossible. I had all horns off and managed to adjust them nearly perfect. They are not 100% but its good enough for me.
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Old Jul 23, 2014, 10:28 PM
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Joined Jul 2007
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Not an adjustment issue, mine are broken. The spline area is cracked open. BTW, the metal ones from extreme didn't fit.
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Old Jul 24, 2014, 02:39 AM
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Quote:
Originally Posted by ChargedDust View Post
Not an adjustment issue, mine are broken. The spline area is cracked open. BTW, the metal ones from extreme didn't fit.
ask if these are ok http://clubheli.com/micro-servo-horn-set-metal-gear/

or if you get this servo you get lots of spare servos with it that fit v120 or just search for this servo arms replacement

http://www.hobbyking.com/hobbyking/s...cro_servo.html
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