RunRyder - Servo Arms - How to center?

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Blitz Helicopters Avro 90 > Servo Arms - How to center?

marked23
Veteran
Location: Lynnwood, WA

These fancy metal servo arms are pretty but not exactly functional.

First one on (rudder servo) and it happens to fit on the splines at exactly the worst angles. So I'm going to have to use a regular plastic servo arm to achieve something close to 90º. The trouble is, the included balls are meant to screw into the included metal arms, not fit into a plastic arm. So I have to go buy a set of balls that are threaded for my application.

Anybody have anything encouraging to say about getting goes-on-one-way-only servos arms to do what you want?

-Mark

05-03-2008 06:31 AM

RyanW
Veteran
Location: Stillwater, Oklahoma

I laid out all of my servos and the arms and test fit them to find the best match. I assume it is the difference in the servo output gears, but I did manage to get them very close to center after switching them around.

05-03-2008 07:01 AM

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JFERA22
Heliman
Location: MONTEREY,CA

Servo Arms

I usuly buy three or four of them. I have been fortunat enough to always get one to work fo me. Usually the spline on the servo horns will be in different angles from one arm to another. Thats what I have found out anyway. good luck.

VOOOLAAAREEE~~~ way up in the sky!!

05-03-2008 07:10 AM

marked23
Veteran
Location: Lynnwood, WA

I guess I'm lucky. All my servo arms seem to have identical spline positioning.

I tried them all on my rudder servo. They all go on the same way.

I'm looking for someone who has MA0103 parts in stock. That should solve my problem.

-Mark

05-03-2008 07:55 AM

Climax
Senior Heliman
Location: West London, United Kingdom

I matched mine as best I could between the servos and then made the final adjustments using small amounts of sub-trim.

Most servos have more throw than is actually used so I don't think there's a problem doing this, I certainly haven't had any issues.

05-03-2008 09:29 AM

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John Benario
Senior Heliman
Location: Atlanta

With only one arm it is unlikely that they will line up exactly. Use sub-trim, that's what it its for.

John Benario

05-03-2008 02:02 PM

marked23
Veteran
Location: Lynnwood, WA

As I understand it, subtrim will move the center point of a servo but not move the end points. So the ccpm servos will move in an unbalanced way and I'll have to tweak the endpoints considerably to get rid of interactions. (I use JR 9303)

This is where a programable servo (like Hitec) would come in real handy.

-Mark

05-03-2008 04:51 PM

RyanW
Veteran
Location: Stillwater, Oklahoma

You are correct. That is why I tried different servos with different arms to find the closest to the center (as the servo will be installed) to minimize the sub trim.

05-03-2008 07:08 PM

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fredd
Senior Heliman
Location: UK - London

I don't think that's correct. End points would move. you can check on the servo monitor.

05-03-2008 08:34 PM

TMoore
rrProfessor
Location: Cookeville, TN

This is what drills and taps are for. You move the arm off center and drill and tap a new hole where you want it.

TM

"If you can do it, it ain’t bragging." - Will Rogers

05-03-2008 08:42 PM

RyanW
Veteran
Location: Stillwater, Oklahoma

The more subtrim you use, the more interaction you have to try to get rid of. On my other eCCPM machines, I experimented with varying levels of subtrim and the interaction would go from near zero with no sub trim added to off the charts when you used an excessive amount.

I would love it if you could move the center point and not effect the travel on each side. Mechanically, the output gear has stops on each end of the range. If you move it off center, then it will further in one direction than the other if you don't program it out in the radio by tweaking the endpoints.

TM- the stock machined aluminum servo arms are what we are talking about and there isn't room to drill and tap new holes. You could use other servos arm, but then it wouldn't match the rest of the machine and we couldn't have that!

-Ryan

05-04-2008 12:14 AM

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Blitz Helicopters Avro 90 > Servo Arms - How to center?

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