Bearings and bushings are milled to the wrong size

[jrevens]

Good post, John. I’m sure you’re right. 4130 tubing is used that way on many airplanes. The bronze sleeve bearings are probably off the shelf parts, again, very commonly used. The fact that some “sizing” has to be done is just one of the tasks that help to meet the spirit and intent of the 51% rule.

[efwd]

Funny that you mention the Mars Probe. Back when I was building my RV4 I called the factory with concerns much like this. Dick Vs reply to me was "remember, you aren't building a Space Shuttle here". Granted, your life depends on your craftmanship but this stuff has been being used for years without problems and as John put it, it needs the 51% rule.

[rwoneill]

John B, very interesting observations. If you're right, we are back to my original conclusion which is that, intentionally or not, the hardware selection is just out of spec.

I'm not talking about bearings and bushings looking pretty. I'm talking about basic functionality. The bearings and bushings from the factory will not function as delivered, full stop! And to get them to function, the builder is expected to perform the task of a lathe with a drill and sand paper. Which is not only incredibly time consuming, but more importantly it is also incredibly inaccurate. I imagine there are a lot of kits out there with some very sticky or very sloppy controls for this reason.

I have a bearing that is a 1/32" smaller than all the others. I can't get it to sit in place without clattering around. Too big can be salvaged, but how am I supposed to deal with too small? Out is spec goes both ways. I guess I have to order another bearing and hope it's too big!

If KF sourced properly spec'd hardware, do we know for a fact that they would not meet the 51% rule, or is that a speculation? There is obviously a price associated with better hardware. I wonder what that would be. Also what do they do in the factory? I'm certain that they don't have a bunch of full time employees milling down bearings in a drill press. They must have a lathe or they have better hardware.