[Kevin Horton]

I'm looking for a source for two AN4-72 bolts. ACS carries the AN4-72A, but I need to use castle nuts. GAHCo doesn't seem to carry them, if I can believe their web store, and a quick web search didn't strike gold. Who might stock these at a reasonable price?

I will use the bolts as rudder pedal pivots for my RV-8, so the ball of my foot can press rudder pedal without getting any brake.

 

[Mel]

Straight bolts can be drilled if you have a drill jig.
Having said that, I have a drill jig, and I haven't had much luck doing this.

 

[Kevin Horton]

Straight bolts can be drilled if you have a drill jig.

Yeah, I thought about that. Even with a straight cotter pin hole made during production, it can be pretty fiddly to get the cotter pin all the way through. I figured it would be pretty hit or miss to drill a cotter pin hole that went straight through the centre of the bolt. I don't want to risk screwing up $20 bolts by drilling a hole slightly off angle.

 

[RV8RIVETER]

Can get them a bit cheaper. I bought mine from McMaster Carr (5 for $8), though not drilled. In this use, if you drill it just slightly off it should not cause a problem, we are only trying to safety the nut. And it doesn't need to a very big hole.

 

[8CW]

In a pinch, I've drilled "A" bolts by putting two nuts on a bolt, one acting as a jam nut to keep the bolt from rotating. Center punched the outer nut on opposite flats then drilled the bolt from both sides undersized. Came back and through drilled full size. The nut allows for a smooth surface to start your hole then acts as a drill guide for the bolt. *Most* of the time it works well... This is also done using a drill press and vise.

 

[Kevin Horton]

In a pinch, I've drilled "A" bolts by putting two nuts on a bolt, one acting as a jam nut to keep the bolt from rotating.
...

Thanks for the advice. That approach sounds workable. I think I'll pick up some grade 5 bolts locally and try this. AN bolts are really overkill for this item. They are also much more expensive, and would take much longer to acquire. I was focussing on using them because of the cotter pin holes.

 

[DanH]

Kevin, I've done the same mod by cutting an ordinary steel rod to length and running a die onto each end. Used all-steel stop nuts, the kind with the thread bore deformed into an oval. The torque necessary to remove them is about equal to that necessary to shear a cotter key.