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  #21  
Old 09-29-2018, 08:59 AM
iamtheari iamtheari is offline
 
Join Date: Nov 2017
Location: ND
Posts: 136
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Quote:
Originally Posted by smash View Post
I had a problem getting the control column to move freely. When built correctly, there is almost no friction and mine was sticky no matter how I adjusted the shims.

I discovered that while back riveting the bearing bracket assembly, I had accidentally positioned the backing plate under the bearing and slightly marred the bearing surface. I didn't realize this until I tried shimming and could not get the assembly to move freely.

The solution was painful- I had to remove the cover rib to gain access to the bearing bracket assembly and then disassemble it. When I removed the bearing, it was stiff when I tried to move it with my fingers and on closer examination I found some scoring on the bearing surface.

Remove the control column and try moving the empty bearing with your fingers- it should move absolutely freely with no catching.

Here's my build log writeup: http://www.smashsrv-14build.com/2016...ishing-up.html
I hope it doesn't come to that for me. But can you share some insight on why you removed the rib rather than removing the bearing bracket from the rib and leaving the rib in place? It seems to me like it will be at least as hard to drill the rib out of the fuselage assembly (especially from the bulkhead) as it would be to drill the bearing bracket off of the rib.

Although despite it not being ideal, I kind of like the castle nut solution posted by mturnerb because it lowers the risk of damaging things while trying to remove and reinstall them after the fuselage forward and mid sections have been riveted together.
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  #22  
Old 09-29-2018, 09:28 AM
mturnerb mturnerb is offline
 
Join Date: Apr 2015
Location: Ponte Vedra, FL
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Quote:
Originally Posted by iamtheari View Post
I hope it doesn't come to that for me. But can you share some insight on why you removed the rib rather than removing the bearing bracket from the rib and leaving the rib in place? It seems to me like it will be at least as hard to drill the rib out of the fuselage assembly (especially from the bulkhead) as it would be to drill the bearing bracket off of the rib.

Although despite it not being ideal, I kind of like the castle nut solution posted by mturnerb because it lowers the risk of damaging things while trying to remove and reinstall them after the fuselage forward and mid sections have been riveted together.
Just don't take my solution as being recommended safe or best practice. I am sharing my experience and my comfort level (based on what I believe to be good advice). I would guess the biggest risk of my approach might be wear over time, so I will keep a close eye out. FYI I did carefully check the bearings for free movement and I'm sure there's no binding related to assembly of the bearing bracket. And I was careful to tighten the castle nut enough that the bearing is moving, not the nut/bolt. I found that there is a very big effect on binding between this level of tightness versus torquing a locknut. I was also careful to use the right length drilled bolt and/or washers as required so that castle nut lined up correctly with the drilled hole.
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Last edited by mturnerb : 09-29-2018 at 09:34 AM.
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  #23  
Old 09-29-2018, 11:29 AM
smash smash is offline
 
Join Date: Apr 2013
Location: Fair Oaks,CA
Posts: 51
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Quote:
I hope it doesn't come to that for me. But can you share some insight on why you removed the rib rather than removing the bearing bracket from the rib and leaving the rib in place? It seems to me like it will be at least as hard to drill the rib out of the fuselage assembly (especially from the bulkhead) as it would be to drill the bearing bracket off of the rib.
Agreed- if you can remove the bearing bracket without removing the rib, go for it. I wasn't able to get my drill in-between the ribs to do that and I didn't want to attempt to remove that many rivets using my 90 degree drill. Also, it would have been very difficult to drive the rivet stems out in the confined space. YMMV
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  #24  
Old 10-02-2018, 09:22 PM
iamtheari iamtheari is offline
 
Join Date: Nov 2017
Location: ND
Posts: 136
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After removing the control column completely, I can see that both bearings are stiff. I can insert a screwdriver through them and rotate them with mild stiffness, but I can't rotate them in the direction they need to rotate with my fingers. I guess I'm going to be doing a whole bunch of rivet-drilling.
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  #25  
Old 10-05-2018, 05:44 PM
iamtheari iamtheari is offline
 
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Location: ND
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My A&P friend who is helping me with the build helped me evaluate this situation and decide on a solution. We will use a 90-degree drill to remove the 8 rivets holding each bearing bracket to the rib, disassemble the bearing brackets, replace the bearings, rivet the brackets back together, and then use flush Cherrymax rivets to reinstall the bearing brackets. Wish me luck!
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  #26  
Old 10-05-2018, 10:49 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
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Quote:
Originally Posted by mturnerb View Post
I had the same situation - spent many hours trying every possible combination of washers/shims I could: finally discussed at length with my tech counselor. He advised me to replace the standard bolt/locknut with a drilled bolt/castle nut/cotter pin: having a bit less torque keeps the bearing from binding. I settled for this compromise since at some point you have to move on....
Be cautious with this approach. The inner part of the bearing needs to be help captive in the arms of the control rod. If this is too loose, the bearing won't rotate and you'll be rotating on the bolt.

Larry
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  #27  
Old 10-05-2018, 10:52 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
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Originally Posted by BillL View Post
Using feeler gauges to determine the last thickness needed is one method of positively determining the shim needed. If an even # of .030 shims don't fit the bill then you can always machine a spacer the exact length needed or Make your own shim the proper thickness.

.
I just did this the other day. Using a feeler gauge is problematic, because the arms are usually not parallel. Your shim must fit when torqued, not when loose. As the bolt is tightened, the arms straighten out.

Don't forget that the L washers are only about 23 thou, so two of those is smaller than one std washer. Mix and matching may get you closer without making a shim.

Larry
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