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MD3614M Rod End Bearing

msmst25

Well Known Member
I'm trying to install the rod end bearings into my elevators, but the holes in the spar and hinge reinforcement plate seem to be too small to even insert the rod end bearing through to the nut plate underneath. All 4 of the holes are too small, and I've tried multiple rod end bearings. I don't see anything in the instructions that indicates I should have enlarged this hole prior to installing the nut plate. I'd appreciate any suggestions.
 
Unibit

With my calipers, it looks like the holes are about 3/1000 too small for the rod end bearing. I'm considering just using my unibit and slowly entering to enlarge to a full 3/8". I just don't want to take a chance on ruining my elevators if there is some reason this isn't a good solution
 
I'm unclear where you are in the build - can you cite a page and step number?

As I recall, the VA-101 threaded inserts were really hard to insert into the pushrods, especially after priming the inside of the pushrods. I had to file down the VA-101s a little bit, and then use a rubber mallet to drive them in. Is that the part you are referring to? The same thing happened again for the aileron pushrods.
 
My recommendation is to open these holes as little as possible (3/8 reamer, drill, Unibit) to get the proper fit to the HS. However, before you rivet the Nut Plate to the spars and doubler(s), open the hole a bit (perhaps with a "W" drill or reamer (0.386")) in order to ensure the rod end will properly engage into the threads of the Nut Plate even in the case the Nut Plate is not exactly concentric with the spar/doubler assembly.

Good luck,
 
Rod end bearing

The elevator is already assembled. I’m on the first step of the assembly of the empennage. I didn’t think that I would need to check those two pieces to make sure that the hole was the right size. I like the idea of using a 3/8” reamer. I think I’ll order one of those unless I hear a better suggestion. I think that will give me a cleaner hole than the unibit.
 
I see where you are now. I don't see anything about enlarging those holes, either. A few basic things to check (not to insult anyone's intelligence - we all make avoidable mistakes). Are the plates overlapping properly? All four holes have both the spar and a reinforcement plate. Is it possible that you didn't keep the four pairs together? Is it possible that the center hole for the rod bearing isn't aligned?

Did you use a K1000-6 nutplate for all four holes? Maybe the problem isn't the holes, but rather the wrong nutplate?

Looking briefly at my elevators, the fit isn't 3/1000 inch, like you suggest. There is enough of a margin for error that if my nutplate was off by a little bit from dead center (and I'm sure it is off a little), the bearings still would fit through the hole into the nutplate.

Or, maybe Van's CNC process made an error somewhere.

Be careful with a unibit or reamer widening that hole - since you have a nutplate installed in each hole, if the unibit pokes through too far, you will damage it.

If you need to increase the diameter of the holes without hurting the installed nutplates, one option would be to use a narrow sanding or grinding tip in a dremel - just poke the tip in there and sand out the edge until the hole is wide enough.
 
Don't be quick to enlarge those holes. Lots of builders and no one else has been reporting an issue. And it's unlikely that Vans has changed anything. My guess (already mentioned by another poster) is that you have the wrong bearings. Double and triple check. Here are the dimensions for that series of bearings, check the housing width and thread size. It's pretty easy to mix up the bearings, so if Vans made a mistake, it would most likely be there rather than a CNC error.
 
I just checked mine and they fit no issues. I followed the instructions. I even have a slight misalignment between the spar and the reinforcement.

Before changing the hole size, measure your rod ends. They are nominally 3/8" (0.375") but mine measure ~0.369-0.370".
 
Is the hole definitely too small or is the rod end just difficult to get started? I recall this step and if you search you’ll see some suggestions for tools to make to help get the rod end in because they are tight in the nutplate by design.
 
Fixed

After reading all the advice on here, and not wanting to make any irreversible mistakes, I examined it more closely. Only two of the holes were too tight, and it was due to a slight misalignment of the doubler plate. The other two ended up being fine (I initially didn't want to force them and risk damaging the threads. It wasn't really obvious until I used a lighted magnifying glass. I ultimately ended up using a dremel to grind off the small bit of metal that was in the way. The cleco pliers then worked great for inserting the bearings. Thanks for all the help and suggestions.
 
Channeling Vic a bit.

Hopefully in all the confusion, you did remember to install the jam nuts.
 
After reading all the advice on here, and not wanting to make any irreversible mistakes, I examined it more closely. Only two of the holes were too tight, and it was due to a slight misalignment of the doubler plate. The other two ended up being fine (I initially didn't want to force them and risk damaging the threads. It wasn't really obvious until I used a lighted magnifying glass. I ultimately ended up using a dremel to grind off the small bit of metal that was in the way. The cleco pliers then worked great for inserting the bearings. Thanks for all the help and suggestions.

Excellent. The tolerance stack up of the holes make a slight bit of misalignment inevitable. With 2 doublers (if the spar had been built with the S/B mod), the tolerance stack-up is even worse. Using the Dremel tool to "clean up" any misalignment is a good way to resolve this issue. When I had suggested a reamer, I assumed the elevator had not been completed.

Good luck,
 
For the future...

During my build I almost always put an old, sacrificial bolt a few turns into the nutplate, prior to final drilling the nutplate rivet holes. Easier to fix problems like this if you notice them early.
 
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