Tightness/Looseness of Aileron Bellcranks

[samiam]

Not to hijack this thread, but my bushings have no slop and rotate well, however some of the rotation is between the bolt and the steel bushings. There shouldn't be any problem with that, I'm guessing? If I tighten the castel nut down too hard it will start to bind, but at the appropriate torque it does allow rotation around the bolt.

[DCASonex]

Not only will abrasive embed in the porous bronze, but some very fine abrasives like emery will embed into steel as well. Best to avoid abrasives on bearing surfaces unless you are sure of what you are doing. Also, reaming is not ideal for sintered bronze bushings either, as it closes off many of the bores. Not a big deal for the kind of very low speed applications here, but can be an issue for higher speeds. Should be able to find additional info on proper insertion of Oilite bushings on line, but generally involves using a proper sized plug inside when pressing into place.

David A.

[Spaceman]

Spaceman
I believe line boring is assembling the parts to be a complete assembly beforehand. Then drilling through the paired bushes in one action, so the holes in are in line and true with each other.

Ah that makes sense, thanks!

[NWade]

Thanks, all, for the education on abrasives and sintered bronze... I learned something new! I'm not sure if its a big deal for our specific application (given the slow rotation speed and low relative wear of these parts); but I'll keep it in mind and would love to find out further information - especially if anyone contacts the factory about this.

however some of the rotation is between the bolt and the steel bushings. There shouldn't be any problem with that, I'm guessing? If I tighten the castel nut down too hard it will start to bind, but at the appropriate torque it does allow rotation around the bolt.

So from what I've read on this board and in emails with Sonex staff, you don't want the bolt to rotate independently of the steel bushing. The bolt & castle nut are supposed to clamp down on the steel and hold them in place. If tightening the bolt causes binding of the bellcrank, then that probably indicates the bolt-head and/or castle nut are rubbing against the ends of the bronze bushings. I had this in one case, and I simply used some fine sandpaper to shorten the ends of each bushing by a couple of thousandths of an inch. That allowed the bolt to be tight on the steel, but freely rotate in the bronze bushings. Previous posts in this thread on abrasives should be noted; although at least in this case the abrasive particles aren't being introduced directly to the bearing surface. Personally, I used WD-40 to spray/rinse the bronze parts after performing these kinds of operations, to minimize any grit getting trapped in the bearing areas; but your mileage may vary.

--Noel
Sonex #1339

[achesos]

We changed a fitting process of this style bushing where I work based upon feedback from a bronze bushing manufacturer's recommendation - to protect the pores of the bushing, these should not be sanded or drilled / reamed to size.
Optimized fitment / sizing should be performed by pressing a hardened steel ball through the bore to enlarge the inner diameter to the correct fit. This preserves the the integrity of the pores with the impregnated oil without risk of contamination (which reduces performance). Could be a challenging setup to perform, but this operation should provide optimized performance for folks that prefer these components to perform up to their maximum. I'm attempting to optimize everywhere it seems crucial (to me), but one builder's priorities will not always match another's. If this were critical to safety, most likely it would be stated as such by Sonex, LLC.

[Area 51%]

I was having a hard time identifying the binding between the bronze and steel bushings. Everything was a "light thumb-sucking" fit until the nut was tightened. Then it bound up. I found the problem when I ran a solid shaft through the bronze bushings of the assembled belcrank mount. Smooth as glass.

What I discovered was the ends of the steel bushings were not perfectly square to the sides. When tightened, they apparently canted slightly causing a bind. The fix was fairly simple. I loosened the nut, rotated the steel bushings, tightened the nut, and checked for binding. Eventually I found a "happy place".

[dbdevkc]

What I discovered was the ends of the steel bushings were not perfectly square to the sides. When tightened, they apparently canted slightly causing a bind.

That is exactly what I discovered also when I had binding only upon tightening the nut. I don't recall my fix, but it may have been the same thing you did.