I have decided to try ball links on my new build. I am going to use them on the bellcrank and elevator horn (no flaps). I went the the web site for Central Hobbies and found a rather large list of items, to the point where it is confusing. Any recommendations as what to use?
I haven't seen any significant problems with the Rocket City #87 or the central hobbies equivalent. Unfortunately, as of this weekend, I cannot recommend the DuBro products. When inspecting airplanes at the Chumley Memorial, after extensive microsurgery, we discovered that one of the ball links had tightened up severely. The link was so tight that it had backed off the screws holding it down over time, which led to it being relatively free, but with extensive free play, as the screws, held with Nylok nuts, were acting as the bearings. Of course it had pounded out the holes in the bellcrank and flap horn, creating free play. When we tightened the screws, it was OK at the flap horn, but the link at the bellcrank was severely too tight. This was all done through a pretty small hole, so we were stumped for a while, but we confirmed the theory by dripping some oil on the ball, at which point it loosened up substantially, although it was still completely unacceptable.
The (very temporary) solution was to back the one screw off just enough to let it turn (but not tilt), and then staking the nut in place with JB Kwik. That at least made pretty sure it was going to stay together, and it will take some time to pound out an oval hole and bring the slop back. The long-term solution is to replace the links with Rocket City links which don't usually have a problem like this. The original airplane with the #87 links is still in perfect operating order, no slop, and minimal drag, even after 30 years. The airplane itself is eligible for "rolling cutoff Classic" and the Monokote has turned to the consistency of talcum powder, and can easily be lifted with masking tape leaving perfect straightly lines.
Paul Walker has gone back to bent-wire pushrods to defeat this type of problem (which is much more important on electric), but at least for IC engines, just get the Rocket City type, select them for the loosest fit, and move on.
Brett
p.s. OK, it looks like you can't get them from Central Hobbies any more. Tom Morris had them the last time I checked.