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Old 10-19-2015, 07:54 AM
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solentlife
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Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
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Originally Posted by dereckbc View Post
PA gave me this for Pull Pull Rudder. I hate it.

I LOVE THOSE screw links ... I use them almost universally now.

OK reading through your first post ... WHY are you taking servo arm of to adjust ? The screw should be available to you when arm, is on servo. If not then you have them 180 degree upside down ...

Second. Pull Pull only goes slack on one line when deflected IF one or both connections at RUDDER end are not in line with hinge line. Get the offset horns that put holes dead in line with hinge line and no slack.

Third it is not necessary to cross lines ... some are better for it if fuselage tapers severely ... but if not - then no need to cross them. Not crossing them also improves the angle to servo keeping them more at 90 degrees - another reason to avoid slack when deflected.

OK - how to modify to have adjustment ..... You can use the solder ends for wire cables. They have a hole across the solder part that the pull pull wire passes through and then you use a CRIMP to fix. Forget all this knots and CA / Glue malarkey. Get into a Fishing Tackle shop and buy fishing trace wire and packet of crimps. Same stuff actually as Model Sellers provide relabelled and price hiked !
So you have your wire trace crimped to the threaded cable end. Now fit a clevis + small nut to tighten to clevis to lock it and clip to servo arm / rudder horn ... whichever end you wish to have adjustable.

Now you can slack the locking nut ... and actually if only a turn or so .. you can turn the cable end while STILL connected up .. till just tight and then lock it with the nut again.

Tip : Do not over-tighten the cables. They need to be reasonably tight but not so they strain servo gears or rudder horn.

Really Derek ... the screw connectors you have are very good ... just needs a little thought to fit to advantage. Unfortunately I'm not at home to photo any links and set-ups for you ...

Here's my 58" Extra with Pull Pull .... look to left of photo and you see the rudder servo and connections ...



With tight threaded nylon clevis ... often the lock-nut is not necessary.

On some models you don't even need clevis or connectors ... you can loop the trace wire through the horn / arm and crimp as is ...

Here's using servo dual arm through a rudder to give horn either side .. with cable crimped :



Here you see other end .. similar ... its a small 30" model lightweight so no big deal to just use Tx trim to adjust.



Yes with this I get slight slack of cable when deflected BUT flight performance is not affected. You also see the screw connectors set so I can adjust while still fitted to servo .. here on aileron.

Cheers
Nigel
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