WilsonFlyer

My Feedback: (13)

I just ordered some aluminum servo arms from AirWild for my 33% Sukhoi. I noticed that they wanted me to specify if my output shaft on my servos was "+" or not and had two different numbers accordingly. It appears that maybe all the metal shaft servos (MG) are "+", maybe?

I've been using DuBro Extra Strength/Length arms on my HiTec servos for quite some time now but there is only one "part number" for all HiTec servos. I've had no problems that I KNOW OF caused by slippage or anything.

Could somebody please explain to me what's going on here?

Thanks!

Rodney

Getting the proper servo arm is very important. Hitec, Appolo and Hobbico all use horns that have an even number of ribs on the button the arms mount on and can be safely interchanged. Futaba, DAD, GWS, FMA and Tower Hobbies all use horns that have an odd number of ribs and can be interchanged. Note: this is only for the standard sized servos, the minies are a different story. One of the big advantages to the odd numbered ribs is that the servo neautral position can be set more conveniently on them, there is usually always one position that gets the horn oriented as you would like it. On the even numbered ribs, it makes no difference how you orient the arms, they are always off by the same amount.

WilsonFlyer

My Feedback: (13)

I understand all that. LOL

But why two DIFFERENT part numbers for "+" shafts and non-"+" shafts from the same manufacturer for AirWild Aluminum Servo Arms?

carrellh

I guess I'd ask Airwild; they should know what they sell.

http://www.airwildhobbies.com/aboutus.asp?title=about

AirWild Hobbies:
23172-B Alcalde
Laguna Hills, California 92653
Tel: (949) 699-1059
Fax: (949) 699-1097
[email protected]

mglavin

My Feedback: (31)

Airwild's early CNC aluminum arms were different than current offering, thus the inquiry. Accordingly Hitecs early MG servos matched the early Airwild arms, which are no longer available. There is a minute physical difference of the output shaft's with + or - gear sets.

WilsonFlyer

My Feedback: (13)

Thank you so much for that informative response.

WilsonFlyer

My Feedback: (13)

Thanks Michael. That's kinda what I figured by deductive reasoning.

What's still unclear to me is why doesn't Dubro have to have two different "models" (if you will) too. Maybe I'm just not asking the right question. Sorry for being stubborn here. I want to understand. There's a lot of money riding on these things and I feel like I ought to really understand why AirWild offers two different models yet noone else seems to that I can find.

mglavin

My Feedback: (31)

The minute difference was a problem with Airwilds arms. If I recall they were a loose fit. The Dubro arms work fine. Another consideration might be Hitecs offering of HD composite arms these are very good components and the per servo package offering has many sizes and or arms included with each set.

JerryBien

Hi LearningMan and all,

This is Jerry Bien of AirWild. Allow me to add my 2-cent worth.

First of all the SOLE reason for AirWild to differentiate Hitec metal gear servo's metal output shaft via the "+" cross-hair scheme is because there was indeed progressive changes to the diametric specification of those output shafts.

First of all, Hitec's 1st generation metal-gear digital servos were built with output shaft WITHOUT a cross-hard marking on top.

Then months in its production we noticed new Hitec digital metal gear servos were built with a output shafts (color changed) and had a cross-hair marking on top. It was fortunate that they had a "+" marking to differentiate between the old and the new. Because we found the new one to have a smaller shaft diameter. This unpublicized change by Hitec caused our arms to fit a little loose (which is a big NO for the intended applications of these arms). Consequently me immeidately retooled and produced a new batch with a "-02" part number suffix . We also changed our servo arm color from blue (for -01 ) to red (for -02 ) to help identify the two versions.

Well ... this wasn't quite the end of things. As things progressed we later also found dimensional variations within Hitec's "+" family of metal output shafts. Although all later output shafts were marked with a "+" on top, but one could notice differences in diameter and even color (which possibly reflect material change). Our suspicion was that Hitec was getting these components from different suppliers who were holding to different manufacturing tolerances and even different materials. This part is our conjecture though! But the fact was "there was inconsistencies".

Anyhow by my recollection it took about 6 months for things to subside. To date, these Hitec digital servos are showing good quality consistency. However please take note of one thing. If you ever had to buy or order replacement metal gears from you local hobby shop, you likely will get any one version of those output shafts and there is no guarantee here. There's old inventory in the pipeline and they must be flushed out. To be honest mostly likely your local dealer or even the hobby distributor would have no idea as to what you are talking about. This comment is based upon my personal experiences.

All and all, I personally believe Hitec digital servos are the best bang for the bucks. I wouldn't commit my own giant-scale planes to use Hitec 5945 if I don't believe its quality.

As for the average nylon servo arms (ie. Dubro, or even Airtronics stock arms that come with a aluminum collar around the hub area), being that nylon is an elastic polymer you can end up with either a loose or a tight fit. This will depend on the process control of the molder. If it is too tight, no problem 'cause you can simply press fit the arm down as the nylon hub can tolerate a minute amount of expansion. If it is too loose, well ... you are out of luck. However Airtronics' solution to deal with loose fitting nylon arm is to encircle the hub area of the arm with an aluminum collar. This can prevent the nylon hub area from expanding and maintain a tight fit to the output shaft.

Like I mentioned earlier, this is just my 2-cent worth. Everyone has a preference and there is no absolute.

Have fun and fly hard.

Jerry Bien
AirWild

WilsonFlyer

My Feedback: (13)

Thank you so much Jerry et all. Those were the exact answers I was looking for and I bet others had wondered too.

Looking forward to installing my new Airwilds in my new Suhkoi 33%.