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Aileron Bellcrank fabrication

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Well-Known Member
Sep 13, 2006
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Here are the steps I used to make the aileron bellcrank. Yours may differ. If I miss anything, please let me know.My plans call for a bushing-type set up. Steen sells one with a bearing, which is how I am building mine.

The first pic shows the lathe cutting the tubing needed for the newly designed bearing tube. You'll need to cut (with precision) 3/4" x .065 4130 tubing to 1.250", 5/8" x .065 4130 tubing to .860, and 3/8" x .065 4130 tubing to .860. So, this will give you the outer bearing tube (3/4"), the pressed-in sleeve (5/8"), and the compression bushing (3/8").


You'll then need to drill a 1/4" hole in the bearing housing. This will be for a rosette weld. Be careful where you drill this...You don't want it in a position that forces you to weld back over it when you weld the prts together. Mark a spot 1/2" from one end and drill there.
Ream the inside of the bearing housing to .625. This will allow fitment of bearing and sleeve.
Press sleeve into bearing housing. Make sure you center it from end to end. To assist you, you may with to use a bearing on one end to take up the proper space.


You'll end up with something like the above pic.

Next, rosette weld the inner sleeve to the outer housing.

You'll then want to draw the fitting in a CAD program of your choice, or draw the old fashioned way. Paste these drawings on some 4130 .100 plate, paying attention to grain direction, keeping it the same way as the bends you'll make.


DON'T drill the holes until you make your bends. Remember, there is a RIGHT and a LEFT!!!!! So you will be making bends different ways.

You next want to bend this bracket according to the plans.

You can hold it up against a flat surface to measure the 1/2" distance the plans call for:


Adjust if necessary. After bending and twisting, drill it out. TWO DIFFERENT SIZE HOLES!!!! One is 1/4" and one is 3/16". It is important to ream to final size as accurate as possible because the bolts that will go in those holes are in single shear, so the closer the tolerances, the stronger it will be.

You should end up with something like this:


A RIGHT AND A LEFT!!!!!!!!!!!!!!!!!!!!!

Next, weld the bearing sleeve in the bracket. A bead on one side is all that is needed.
The bearing sleeve should protrude 5/16" on the BOTTOM of the bracket.
The weld bead should be on TOP of the bracket.


When you are done, you should end up with a RIGHT AND A LEFT!!!!!


Powdercoat, install bearings and compression sleeves.
The bearings used are R4zz. The dimensions are .250 x .625 x .196. Put an AN960-4 washer on each end and you're ready to go!!!

Time to mow the lawn....I shall build more tomorrow. Edited by: scottly

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