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Advice on Ball Links

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Old 01-02-2003, 01:39 PM
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coomarlin
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Default Advice on Ball Links

I've decided to use ball links to connect the 4-40 pushrods to the servos on my UCD3D. I've choosen this method instead of the recommended L-bend with retainer clip. I thought about Z-bend also, but do not like the lack of adjustability or the tendency for slop to develop over time.

I've actually never used ball links and after looking at my local hobby shop and at online retailers there appear to be 2 common types. The Snap-on Type which is very self explanitory and the enclosed ball type .

Which of these two would be a better choice for the UCD? Is one safer than the other? Do these connectors have tendencies to go bad or fail?

There was one other type made by Sullivan that was listed on Towers page that I wasn't familier with that is shown here. I know my local hobby shop does not sell this type so I'd need to order it from tower which I'd rather not do.

Help and suggestions would greatly be appreciated. Thanks.
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Old 01-02-2003, 02:16 PM
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Jemo
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Default Advice on Ball Links

use the enclosed ball type
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Old 01-02-2003, 02:44 PM
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ChuckAuger
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Default The ones I like are..

The Dubro brand, but not the EZ Adjust series. The ones I buy are labled by Dubro as "Car Line", but they are identical to the aircraft ones except they are packaged like I want.

For a 4-40 rod using a regular servo arm, I like the #2139. This link screws over a 4-40 rod, but the screw the ball goes on (and screws to the servo arm) is 2-56.

For a 4-40 rod and an aluminum servo arm, I like the #2161. This link screws on a 4-40 rod, but the screw the ball goes on is 4-40..works great for aluminum arms that are already tapped 4-40. The reason I don't like these on regular servo arms is (a) the 2-56 screw will thread right into the hole on the arm with just a little enlarging of the hole, and (b) I think it leaves too little plastic around the screw when you drill the arms fo 4-40..plus a 2-56 screw is plenty strong compared to a plastic arm.

The EZjust may work fine, but they have a screw to fall out and I've never needed to adjust a ball link, just replace it.

Edit here...I just went back and looked at the link you posted....the Enclosed version you show is the right style, but stay away from the 2mm ones..they are for the 2mm rods on helis and the like.. If you are using 2-56 rods, go with the #2135
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Old 01-02-2003, 02:56 PM
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coomarlin
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Default Advice on Ball Links

That is excellent information. I'm using standard control horns and I'd rather not have to drill them out to fit a #4 screw. Like you said that leaves too little plastic. Hopefully my hobby shop carries the 2139's because they would be exactly what I need. A 4-40 pushrod capatible with a 2-56 screw for mounting to a standard servo. Thanks again.
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Old 01-02-2003, 03:02 PM
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Vince
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Default Advice on Ball Links

Use the enclosed type, not the snapon type for flying surfaces. I also use a washer on top of the ball link that the retaining screw goes through, this keeps the ball link from ever coming completely off the ball. Use blue Locktite on the retaining screw threads and nut, and if space allows use two nuts to lock together.

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Old 06-27-2003, 02:38 PM
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BillHarris
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Default Advice on Ball Links

I've used the "snapon type" on throttle linkage, and control surfaces for light "nostalgia" class sailplanes (light servo loadings).

The "enclosed ball type" is perfect fo large control surfaces, especially where -zero- play is needed. They use this type on helicopters ('nuff said).

The Sullivan sleeved ball joint is useful where the control surface needs to be removable (like tailfeathers) or needs to be adjusted in a tight place.
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