July 28, 2008

Bellcrank Bushings - continued - 2.0 hrs.

I feel like I'm on a roll with these bellcranks, so work continued today. The first task was to figure out a way to secure the brass bushings in my drill press so that they can be reamed out to a larger size. The bolts won't fit in them until this is done, so this is a must.

I took a block of 2 x 4 and clamped it in the drill press, and drilled a hole the same diameter as the bushing. I want this to fit tightly.

It's kind of hard to see here, but the next thing I did was to run this block through my table saw and rip it in half, right through the middle of the hole I had just drilled. Then you pull the block halves apart, insert the bushing, and clamp it together with these squeeze clamps. Then the whole assembly can be clamped to the drill press table. I took out the drill bit and put my reamer in the chuck, then centered the bushing in place under the reamer. This technique holds the bushing firmly in place, exactly parallel to the reamer. Then, reaming out the hole was easy.

Here are both bushings, reamed and ready to go into the bellcranks. As you can see, the bolts now fit inside perfectly.

Finally, the bushings get a thin layer of grease on the outside surfaces that I had polished, and slide into the bellcranks. The bushings need to be slightly longer than the bellcrank, because the washer and bolt will be torqued down to the bushing, and therefore the bolt won't rotate inside the bushing. The bushing rotates inside the bellcrank. Make sense? Actually, to be even more accurate, the bellcrank moves around the bushing, which will be held in a stationary place.

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