Tailbone repair

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63markB
Posts: 352
Joined: Wed Dec 08, 2021 11:51 am
Location: Delta county Texas

Tailbone repair

Post by 63markB »

Can one assume that all the wear on the tailbone is on the “outward” end of the top hole and the inner end, side of the bottom hole? And should the pin be 90 degrees from the top frame member of the tailbone? Dang, sorry so long but don’t know how else to word it.
Windcatcher530 Dan
Posts: 1900
Joined: Sun Mar 28, 2021 4:06 pm
Location: Alcove N.Y.i buy and restore

Re: Tailbone repair

Post by Windcatcher530 Dan »

If i translated it right. Yes
mtblah
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Joined: Thu Mar 26, 2020 12:09 pm
Location: new braunfels TX

Re: Tailbone repair

Post by mtblah »

180 degrees and I threaded a set screw to hold in position .
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63markB
Posts: 352
Joined: Wed Dec 08, 2021 11:51 am
Location: Delta county Texas

Re: Tailbone repair

Post by 63markB »

This part Mike,
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mtblah
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Joined: Thu Mar 26, 2020 12:09 pm
Location: new braunfels TX

Re: Tailbone repair

Post by mtblah »

OH , my bad , wrong part in my mind .
your right , it is "worn "
63markB
Posts: 352
Joined: Wed Dec 08, 2021 11:51 am
Location: Delta county Texas

Re: Tailbone repair

Post by 63markB »

If I overlay this with 1/4” flat bar and locate the hole to where the back side of the hole matches the existing hole shouldn’t it be correct? This tailbone is over a grand at Aermotor
Windcatcher530 Dan
Posts: 1900
Joined: Sun Mar 28, 2021 4:06 pm
Location: Alcove N.Y.i buy and restore

Re: Tailbone repair

Post by Windcatcher530 Dan »

Mark before you do the over lay make sure the tailbone will still fit between the two ears on the gear box
63markB
Posts: 352
Joined: Wed Dec 08, 2021 11:51 am
Location: Delta county Texas

Re: Tailbone repair

Post by 63markB »

Yes sir. I was goi g to do in on the top piece only. And then machine a new pin with a longer threaded end
Windcatcher530 Dan
Posts: 1900
Joined: Sun Mar 28, 2021 4:06 pm
Location: Alcove N.Y.i buy and restore

Re: Tailbone repair

Post by Windcatcher530 Dan »

Oh okay sounds like you have it figured out.
Ron Stauffer
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Joined: Fri Dec 14, 2018 10:25 am
Location: Uncompahgre Plateau Montrose CO
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Re: Tailbone repair

Post by Ron Stauffer »

Generally the wear on the bone is elliptical as you describe but not always an ellipse directly inline with the bone. Variations come either from the amount of tail spring tension or being in a gusty wind area. Even tho the tail pin is fixed to the bone, there is some movement. If you look at the wear pattern on the top of the lower angle brace in your pic 2, the wear is not quite inline with the bone. When tail pin holes in the case are worn, they are off at an angle.

The bone must be for a 16 or 14 as it has the riveted extra brace for the bottom short bolt. The top flat bar and the bottom angle of the bone are NEITHER 90 degrees from the tail pin. The degree angle between top flat and tail pin is different for each size of Aermotor mill. You can attribute this to Aermotor cases not being uniformly scaled between sizes. The lack of exact scaling is evident with different issues in one size Aermotor and not in another.

I remember assembling a 12 many years ago that had a bone overlap repair and longer top threads on the tail pin as you describe. It was difficult to assemble because you had to enter the top flat bar before the larger OD of the tail pin got in to the upper lobe of case.

I have seen repairs on larger bones where an exact duplicate of the end 6" was butt welded when the old end was cut off. Evidently these repairs held. Back in the day when Aermotor had reps in the field, it seemed there was a lot of shared info on and commonalities on repairs.

Ron Stauffer
Montrose CO
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