Anyone use these?

[Glyn44]

Is there something inherently wrong with disc servo arms? I ask because there is little evidence of their use in forum photographs, or in aircraft at the club field

[Denis Watkins]

To get aileron differential on my Flair AT6 Glynn, some years ago.

You put your choice of connector in the end holes of the same row of 3 in the disc,

I chose ball joints, and they go 180° to left and right aileron, giving more up than down when operated

[Rob Fairweather 1]

I have a large tin, full of them.

The smaller ones make excellent things to draw around when making cut outs or for radiusing patches. The larger ones, well . . . .

for marking bigger radii.

Edited By Rob Fairweather 1 on 14/04/2020 16:30:48

[Jon H]

I dont use them often as i usually need more movement, but that is the only reason i dont use them more than i do

[Robin Colbourne]

As the arms can't snap off them (because there aren't any), the next weakest link in the chain is the servo gears. Its easier to change a servo arm than rebuild a servo.

[Glyn44]

Ok thanks I hadn’t realised any of the above. Cheers.

[Glyn44]

Ok thanks I hadn’t realised any of the above. Cheers.

[Jimbo565]

These discs are standard issue on the Ripmax Micro SD200 servo

[cymaz]

They make good washers if you drill out the centre

[Peter Miller]

Posted by cymaz on 14/04/2020 18:26:19:

They make good washers if you drill out the centre

Yes, I have used them under the heads of nylon wing bolts

[kc]

If you put a clevis THROUGH the holes it will tend to bind unless the lower part of the disc ( or 6 arm type) is cut away. No problem if you use ball joints or anything entirely above the disc.

[john stones 1 - Moderator]

They are the soft centred chocolates of the servo arm World, they only get used/eaten, once all the others have gone.

[Richard Acland]

I use them on the throttle servo to make the cam that operates the on board glow micro switch.

[leccyflyer]

I've got a few of the circular discs on models with one central aileron servo and torque rods, with a Z=bend at the servo end and a clevis on the torque rod end.

[Gary Manuel]

I use them as the basic building block for home made / custom servo arms. They allow the arm to be attached to the servo with PERFECT geometry with zero sub-trim dialled in, regardless of the make of servo / number of splines etc. Having the geometry perfectly centred with zero sub-trim allows for maximum travel that is equal in both directions.

Simply align everything how you want it, then drill / bolt through the disk and custom arm to fix it in the required position.

Here's an example:

These are kit supplied arms attached to standard disks. I've also used the same technique to attach (single and double) arms I have made myself from Epoxy Glass Board.

[Lindsay Todd]

Best use I have found was for my 3 cylinder dummy engine on my Dawn Flyer - never throw anything away

Linds

[Nigel R]

I actually use them for servo horns.

On ailerons, the control rod is often a short length of threaded wire, I just pop a Z bend into the rod and then it goes into the disc arm with no fouling. As Denis points out, you can differential very easily by using the end hole in the row of three, this especially useful with single servo torque rod aileron controls. Simple, cheap, effective setup.

Or you can thread a ball link in to them for throttle cable use.

Plus Gary's example is a good 'un, use them to bolt a giant arm to when making controls on a 3d type.

Edited By Nigel R on 15/04/2020 11:46:34