Finishing the tank support brackets

One more task on the tank support brackets – drilling holes that accommodate the bolts that attach the tank support brackets to the tank flanges. I copied an idea from fellow builder Mike Bullock and used a 1/4″ OD drill bushing to drill a #40 pilot hole in the tank angle. The bushing fits snugly in the 1/4″ cutout on the tank support bracket, ensuring that the hole is nicely centered.

Tank support drill bushing

Here’s the bushing clamped in place on the aft side of one tank bracket…

Drill bushing clamped

I then used the #40 hole to center a 1/4″ drill bushing on the front to the bracket, held in place by a piece of 0.25″ aluminum bar.

Larger drill bushing

Here’s the final result…both sides came out pretty nicely.  A 1/4″ bolt slips neatly into place.

Final hole drilledI screwed up a little and didn’t lay out the orientation of the platenut that gets riveted to the tank angle – I’ll have to take care of that when the wings go on for final assembly.


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