Ryans Rebel

My Feedback: (12)

I recently purchased a model that uses 3 9206's per aileron. I'm having trouble deciding how to gang them safely. The easy solution would be to replace them with programmable digitals or use a match box. However I would like to not go that route as I'm trying to use what I have.

What else can be done besides using a disk and drilling a hole where needed? If I use aluminum servo arms, there is virtually no way that all 3 will line up properly because of the splines of the servos not matching with one another. Does anyone manufacture a servo arm that is adjustable regardless of spline orientation (as to center one servo with another)?

Any other Ideas or possible solutions are welcome!

Ryan

Tired Old Man

My Feedback: (1)

Without using a Matchbox or one of it's equivalents, I'm afraid that you will be in for a geometry lesson you will never forget, or want to repeat.

sweetpea01

My Feedback: (10)

it can be done.......and you can match splines and/or use adjustable tierods from H9 so that you can match each servo throw. It was a pain matching my 2 arms on my 35%.......can't imagine matching 3

Diablo-RCU

My Feedback: (1)

You can also cut the aileron into 3 sections - each one powered by a single servo. Think of a setup like split flaps.

Ryans Rebel

My Feedback: (12)

You guys make it sound worse than I think it is. Why can't you just plug all the servos in, turn on the Rx to center them, use circular disk and drill a hole "centered" and go? How did all those TOC guys do it for years before programmable servos or match boxes???

Ryan

Tired Old Man

My Feedback: (1)

The reality of it is that was pretty much what they were doing. They also had some of the servo matching products quite a bit earlier than we got them. At least the high end sponsored pilots did. Looking back a little in time, the 3 servo aileron wasn't very widely used until fairly recently.

Yes, you can make up your own linkage using servo arms such as those supplied by Nelson Hobbies. The first two servos aren't too bad to match up if you have the right transmitter types, but the third becomes a devil of a time. In any case, keeping the linkage geometry as close to the same in travel lengths is mandatory with or without Matchboxes, but the travel adjusts for the third servo can be a bear.

I would also suppose that you will be using multiple "ywe's" to connect the servos to the receiver(s)? That will be another dilemma you will get to deal with.

The upside of not using a servo matching component is that you will save about $120.00 for a plane using a total of 6 servos on two ailerons. Plus a couple of extensions. The down side is that you will spend many hours trying to save $120.00, and perhaps end up with electrical issues at the servos.

Just my .02, but I do hope you find a way to make it all work properly.

rmh

I am lazy and cheap - so I take the cheap lazy method.
first make up a triple Y harness from two Y connectors
line up all three servos to be used.
plug all three into a single channel
make sure they all throw the same amount -and when stopped at any position - all three are at same degree of movement
It does not matter one tiny bit if one servo is faster or slower -or if one is a digital or a non digital.
but stay in same brand servo!
OK now say you have a JR 8411 and a 4721 and a 735-
watch em- I would bet all swing same distances but not at same speed -
IF so - good enough
Now using a straight edge and some good eyesight - make your aileron setup such that the center of each servo output is exactly same distance and angle from the attaching point of the aileron horn --to it's respective hinge line.
Now attach your arms of choice to the servos -
and get positions as close as they will go.
Finally re engineer ( Dremel tool) the servo mounting holes to allow each of the servos to be mounted "twisted " relative to it's output --as required to keep GEOMETRY all the same
some servos will be parallel with original position -some won't but it matters not one bit as far as performance obtained.
Sloppy engineering ?
call it what you want but it works and eliminates any servo fighting
As for diffences in servo speed or rated speed -forget it
the surface will only move as fast as the airloads permit anyway -
I have Matchboxes and use em if needed - but in most cases - getting geometry correct - solves all the problems.

Nogyro

My Feedback: (10)

Dick,

Thanks for takin the time for that great explaination. I put that one in the ole folder.

the-plumber

I build temporary jigs on which to build the linkages, using measurements from the model to build the jig. Gotta get the linkages identical. I always make the linkages adjustable on both ends 'just in case'.

Then I use one of [link=http://www.radiosouthrc.com/pro-servo_driver.htm]these[/link] to set the servos to center. Once in a great while I have to twiddle with the centering pot in a servo to get the output degree wheel to match the others, but not very often.

The only other trick I know is to connect the linkages at 'zero' - with the servos installed and with the servo output arms attached to the linkages -but not mounted on the servos-, I 'walk' the adjusters until the servo output arm drops onto the splines correctly and with no tension either way. Run the arm screw down, and I'm done.

Then again, I don't build models which need triple servos on a flight control surface 'cuz I ain't ridin' in the beast anyway - I figure paired 5301s on six volts will handle pretty much anything smaller than rider scale.

Rcpilot

My Feedback: (78)

Here's a thought:
Some servos have a small screwdriver slot in the top of the potentiometer.

Take the servo horn screw out and remove the horn from the servo.

Look down inside the output shaft and you might see a very small slot in the top of the potentiometer. You can use a tiny screw driver to adjust the center of the pot. Put the screwdriver in and turn it a little bit either way and you can see the output chaft move.

If there is an adjustment screw in there, it will be obvious. You can put your horns back on and just leave the horn screw out for now. Build all your linkages to the same length- or whatever you need for your application. Then just use the tiny screwdriver through the center of the horn and output shaft to adjust the center of each servo.

I've done this with some JR servos. You can get them all centered up perfectly with some time and a straightedge.

Tired Old Man

My Feedback: (1)

Now that was both interesting and potentially very useful.

Thanks for sharing that.

JoeAirPort

My Feedback: (41)

Yeah that was a new on for me. Imagine if the Hitech programmer could do that ? (no mini screwdriver needed).

rmh

I have not seen any adjustable JR servos in some time .
What model # servos are you adjusting?