Control stick assembly, which should rotate?

[swisseagle]

Hello builders

One question about the controll stick assembly, RV-7A, DWG 38 bottom left

Which is supposed to rotate?

The WD-611 (controll stick right/left weldment) around the bushing
OR
the bushing around the AN3-27 screw?

The nut is a castelated nut, so I think you do not tighten to std. torque.
This would mean that the bushing is rotating around the screw and the
bushing which is anyway a bit tight in the WD-611 (disorted after welding I
think), does not rotate.

Does this seams right?

Thanks for your input, regards,

Dominik

 

[DanH]

The bushing is slightly longer than the tube on WD-611. The bolt clamps the bushing between the ears on the WD-610. The bushing is stationary, and WD-611 rotates around it.

 

[swisseagle]

This gives a bit of play!

Hello Dan

Thats right!

The problem I have, the tube was out of shape after the welding, then they where pushing a reamer throu it, so on one end I have an elipse (1/3 of the diameter of the original hole, 2/3 of the diameter of the reamed hole).

This give quite a bit of play which I dont like.

What is, when I glue/press a bushing into the stick-tube and let the bushing rotate around the screw, in this case I have much less play.

Also my tube is by 1,5mm (0.06") shorter than the distance between the ears, would you put a washer inbetween?

Thanks,

Dominik

 

[DanH]

The problem I have, the tube was out of shape after the welding, then they where pushing a reamer throu it, so on one end I have an elipse (1/3 of the diameter of the original hole, 2/3 of the diameter of the reamed hole). This give quite a bit of play which I dont like.

Poor craftsmanship. Send it back to Vans for an exchange, or cut the tube off the weldment and have a local shop TIG a new one into place.

What is, when I glue/press a bushing into the stick-tube and let the bushing rotate around the screw, in this case I have much less play.

For now. Less bearing area so wear will progress more rapidly. That said, it is not a horror story to have the bushing rotate around the bolt. Lots of classics had control sticks pivoting on bolts (a J-3 Cub, for example). However, that doesn't make it the best way. We are trying to build the best airplane possible, right?

Also my tube is by 1,5mm (0.06") shorter than the distance between the ears, would you put a washer in between?

Yes, use washers as required to shim so the ears are parallel when clamped.

 

[Charles in SC]

Have a good look inside of the tube. When welding this type of joint it takes a very careful welder not to melt almost all the way thru and get a build up or blister inside the tube. This can be cut out with a drill, reamer, or dremil type grinder most of the time.
Good luck and let us know what you do to make it right.

 

[swisseagle]

How it worked!

Hello Dan and Charles

- Re-order .. no thanks, unti this part is here in europe it cost about 3x the price and it will be the same quality ...

- cutting off and reweld, this would be good, but first difficult to get the 4130 material here and find a good welder too. Not to speek when I have to buy material by ACS and let is send over, same as above.

It is done so far! This is how I have done it:

- Pressed a dowel of hard steel (shaped like a bullet) throu the tube, this gives "shiny" spots where it touches and straigthen it a bit.

- Grinding with a Dremel the shiny spots.

- Fabricatind a bushing on the late that is 0.004" bigger in diameter.

- Inserting the new bushing and look where it touch the wall of the tube. I found that the tube is bent on both ends about 1/2 - 3/4" from each side.

- With a steel pin inserted to the position where the bent started, corrected the tubing until my bushing was going in and out nicely.

- Grinded on the late the bushing in the center by 0.002" - 0.003" less than on the sides, this helped also.

- Fabricated brass washers that where going over the bushing and reducing the play from the tube on the bushing, thicknes 0.014" each, endplay also 0.014"

Used wheelbearing grease by installing it, all is fine, but it needed a lot of time!

Vans should weld a tube that has a smaller inside diameter and drill and then ream it propperly. The problem of using a drill only is, the drill will follow the bendet tubing, and a reamer will cut it straight.


Thanks for your inputs!

Regards Dominik