Rudder Post/bar typo

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PoconoJohn
Posts: 40
Joined: Tue Jan 14, 2020 9:07 pm

Rudder Post/bar typo

Post by PoconoJohn »

I have a problem with the rudder post (or maybe it's the rudder bar).

As per plans, I drilled a hole in the rudder bar to accept a bushing 1" long using 3/8" 18 ga (.049) tube. Plans show a 5/16" inch bolt welded to the rudder post and the rudder bar (bushing) rides on it, so I naturally drilled a hole in the rudder post for AN5 (5/16") bolt.

A 5/16" bolt (AN5) does not fit in a 3/8" 18ga tube.

To accept AN5, I'd have to drill a hole in the rudder bar for 1/2" 20 ga (.035) which looks too large for the rudder bar. I'm inclined to weld a AN4 into the slightly larger 5/16" hole in the rudder post. AN4 will fit the rudder bar bushing.

Anyone run into this?

John C

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Richard Roller
Posts: 68
Joined: Mon May 22, 2017 11:14 am
Location: Olathe, Ks.

Re: Rudder Post/bar typo

Post by Richard Roller »

John.

After you weld or braze the bushing into the rudder bar you ream the bushing to accept a 5/16" bolt. You will want a snug fit, no slop. Ream to .313" - .3135". I'm assuming you are using an AN bolt to mount the rudder bar.

If you weld the bushing it may be very hard after it cools down and be difficult to ream. You may want to relieve the bushing by heating to a cherry red and slowly cooling it down. Like relieving a tube joint after welding.

Richard

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taildrags
Posts: 334
Joined: Tue Mar 07, 2017 10:39 pm

Re: Rudder Post/bar typo

Post by taildrags »

I had some slop in that connection when I got the airplane and if I remember correctly, I was able to find a metric bolt that provided a better fit. M7 maybe? That's 0.2756" and 3/8" .049 tube has an ID of 0.277"... a gap of seven ten-thousandths. If you use an AN4, the gap will be as much as 1/64". Too loose.

Oscar Zuniga
Medford, OR
Air Camper NX41CC, A75 power

PoconoJohn
Posts: 40
Joined: Tue Jan 14, 2020 9:07 pm

Re: Rudder Post/bar typo

Post by PoconoJohn »

Thank you Richard and Oscar. I am using AN5 in the rudder post hole. I will ream the .049 bushing. Is there any reason I can't ream it before welding? I can easily ream it in my lathe.

John C

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Richard Roller
Posts: 68
Joined: Mon May 22, 2017 11:14 am
Location: Olathe, Ks.

Re: Rudder Post/bar typo

Post by Richard Roller »

I wouldn't think it would be a problem, if you are comfortable welding the bushing that thin. You would be at about .030".

PoconoJohn
Posts: 40
Joined: Tue Jan 14, 2020 9:07 pm

Re: Rudder Post/bar typo

Post by PoconoJohn »

I'll weld the bushing first, then drill into it followed the reamer. It'll be interesting to see what it looks like when I'm done. Won't be much left I guess.

John C

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