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Thread: Control column problem and solution

  1. #11
    Senior Member
    Join Date
    Nov 2019
    Location
    Leavenworth WA
    Posts
    613

    Default Re: Control column problem and solution

    Quote Originally Posted by cpdutch View Post
    OK. After trying multiple combinations and variations of every solution in this thread over a 3 day period I thought I had it licked, and then... I torqued the bolts/nuts that hold the plastic/nylon bearing to the recommended 20-25 in-lbs. Only used 20, which is very little, but I noticed right away that it was more than I had been tightening with regular wrenches. It bound right up, so it was time to rethink this whole approach. The washers under the bolt heads were clearly leaving a deep impression in the nylon bearing/block which seemed like a poor use of the material. Essentially it was cold-flowing under pressure, and since the bearing needs to be held in place by a torqued bolt/nut combination I came up with another approach. I got a piece of 3/16' I.D. stainless steel tube and cut sleeves that would slip over the bolts. Opened up the holes in the bearing block and set them in-place. Their length was such that the clamping force would compress against the sleeve before overly compressing the bearing block against the control column. A little fine adjustment in trimming the sleeves to the right length was a lot easier than sanding more of the bearing block. (I noticed that the shape of the bearing opening was becoming slightly oblong, so I really didn't want to sand any more.) Result - I was able to get a positive contact between the control column and the bearing, and the bearing was held more firmly in place as the sleeves were positively clamped against the tab. It's a variation of the proper approach to design an O-ring seal. The metal-to-metal contact should occur before O-ring channel compresses the O-ring more than a certain % of the O-ring thickness.

    Using all the prior suggestions yielded decent movement only if i didn't get a decent torque on the bearing, so this approach solved that issue.

    Am interested in other's thoughts on this approach.
    Dan Yocum (One Lucky Fox) had a solution for bearing block that was perfect. Go to the Build Logs section and look at One Lucky Fox build, post #35. I did this and it worked perfectly. No deformation of the block, torqued the bolts up and the stick was smooth fore and aft. Also took a LOT less sanding to get it right.

    Gary
    Gary (Geek) Phenning
    Leavenworth (Not the Prison), WA
    Kitfox STi in Building Stage

  2. #12

    Default Re: Control column problem and solution

    I decided to replace the bolts provided with bolts drilled for cotter pins. Then I torqued it to snug using a castellated nut, but still allowed easy stick movement, and secured it with a cotter pin.
    Greg Anderson
    7SS in "production" : https://eaabuilderslog.org/?s=ganderson
    Richland, WA

  3. #13

    Join Date
    Jun 2021
    Location
    Huntsville, Alabama
    Posts
    16

    Default Re: Control column problem and solution

    Quote Originally Posted by Geek View Post
    Dan Yocum (One Lucky Fox) had a solution for bearing block that was perfect. Go to the Build Logs section and look at One Lucky Fox build, post #35. I did this and it worked perfectly. No deformation of the block, torqued the bolts up and the stick was smooth fore and aft. Also took a LOT less sanding to get it right.

    Gary
    The picture One Lucky Fox posted of his solution is exactly what I did as well. The only thing I did differently was I sourced my stainless steel tube from a local RC hobby store at about half the price and I got it the day I needed it.

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