Elevator Binding

[Oregonfox]

I’m not sure folks are still reading this thread but, do you know how much torque is supposed to go on the nuts attached to the through bolts? I’ve had issues done all that is previously suggested on this thread ( bending the elevator straight, filing the weldments for space between the tabs, creating free movement of the steel bushing between the bronze bearing and the bolt while keeping the original length) and as soon as the nut are tightened beyond a just snug fit, the elevator seriously binds. I can even see the tabs move inward toward the bearings/bushings when tightening. The nearest torque value I can find is on the chart given in the builder’s manual, which is 25 in/lb.

[FlyinFish N928M]

I’m not sure folks are still reading this thread but, do you know how much torque is supposed to go on the nuts attached to the through bolts? I’ve had issues done all that is previously suggested on this thread ( bending the elevator straight, filing the weldments…..…The nearest torque value I can find is on the chart given in the builder’s manual, which is 25 in/lb.

It might be a manufacturing problem that you may consider bringing up with KF. You may want to consider mounting the leading edge of you horizontal stab to the airplane, along with your v-braces properly adjusted, then attach the elevator to see what kind of movement or binding you are getting. By filling the bushing weldments down to allow for your elevator tabs to align properly seems like the proper corrective action. The bolt you snug down is meant to compress onto the bushing, only the bushing should move in a freely rotating, lubricated weldment on the horizontal stab. Maybe the weldment on the stab are out of alignment. If things are grossly out of alignment, video and photo document your issues and send them to John and Brandon at KF and let them formerly address before going to far any one direction.

[patrick.hvac]

This stuff isn't NASA precise. If the barrel is longer than the bushing, the tabs will bind.
Either need to shorten the barrel or make a longer bushing. By the location of your tabs in the photo, you don't have much of a choice.

[FlyinFish N928M]

The bushing should just fit in-between the tabs on the elevator. You will have to file down one or both sides of the stab weldments, possibly in different amounts to get the correct tolerances. Nope, nothing NASA precise about it. You might want to clamp and weight down the stab down to a flat table or door to achieve straight and level. You can pull a fish line or heavy thread from end to end to find straight. then attempt to fit in the elevator as it should while paying attention to where the material should come out. Make this adjustment by finding the best average location across all 4 elevator tabs. This will be a slow process, but you will arrive in the end with a well fitted horizontal tail. During the manufacturing process welding typically deforms materials from stock dimensions.

[Oregonfox]

Thanks for the response. Yesterday I emailed KF and am waiting for a reply. In my first email to KF last week they suggested I check the straightness of the elevator and HS spars. We straightened the elevator spar and it helped a bit. The most obvious issue at the moment is watching the tabs move ever so slightly inward with only a bit of tightening of the bolt/nut even though there has been no shortening of the bushing length. All of the weldment/bronze bushing combinations are filed to be clear of the tabs. By your reply, I feel that I have done the proper things so far and not done damage.

It might be a manufacturing problem that you may consider bringing up with KF……If things are grossly out of alignment, video and photo document your issues and send them to John and Brandon at KF and let them formerly address before going to far any one direction.