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  #1  
Old 08-22-2021, 09:23 AM
RV701775 RV701775 is offline
 
Join Date: Jul 2019
Location: Boston, MA
Posts: 94
Default Rudder Counterweight Questions

I match drilled the rudder counterweight to the r-912 counter balance rib, but while match drilling in the drill press, it wallowed out the aft hole in the soft lead. The hole in the rib was fine. Because of the wallowed out hole in the lead, I replaced the counterweight and have the following questions:

1) The new counterweight appears to line up with the holes in the rib well. Is it acceptable to replace the weight with another that was not precisely match drilled if the holes line up fairly well? How precise must it be? You can see in the photo the #10 bolts go through pretty straight (these were #10 hardware store bolts I used temporarily while drilling to hold the pieces together): https://eaabuilderslog.org/?blprojen...&listcat=&sid=

2) My #10 screw dimple die will not fit through the #12 hole called for in the plans. I plan to start the counterweight dimple in the rib with a #8 and finish it with a #10 once the hole is stretched a bit to fit the correct dimple die. Is this an acceptable approach or is there a better method?

3) When countersinking the lead weight, do I want to go .007 below flush as I would with other countersinks? (see section 5 page 8 of manual)
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  #2  
Old 08-22-2021, 10:57 AM
mc607 mc607 is offline
 
Join Date: Apr 2014
Location: Canada
Posts: 67
Default

#1
You should be fine. I put a good smear of proseal under my counterweight to secure it in place, forever.

#2
You have an issue with your dimple die set, or drill bit. Figure out which one. The pilot on a #10 screw dimple die set will go through a #12 hole. If you havenít got one yet, pickup a digital micrometer. Itíll be useful for the entire build.
Donít try and stretch it. Itíll crack. Going forward in the build, ensure you do an excellent job when you deburr any drilled holes when you get in to the bigger dimple dies like the #8, #10 screw size. I mean really smooth. I use the swizel stick, then a light sanding and then a good rub with scotchbrite. I have cracked them by not deburring properly.

#3
The reason for the .007 below flush was to ensure first time builders, like me, donít go too deep when countersinking. Using a dimpled sample piece of skin to check depth of c/s holes was resulting in going too deep and screwing up a perfectly good spar. I know. I donít believe it would apply to the lead counterweight. Flush should be fine.
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  #3  
Old 08-22-2021, 11:57 AM
RV701775 RV701775 is offline
 
Join Date: Jul 2019
Location: Boston, MA
Posts: 94
Default

Thanks for the feedback. I will likley put a smear of pro-seal as well.

The #12 drill bit is 0.189", too big for a #10 die pilot. I contacted Cleaveland to check the pilot and they stated that "Our Die pilot is 0.1905 +- .00015 so 0.19035 to 0.19065" and suggested a #10 drill bit. This would require me to drill the hole to a #10, .1935 in for this to fit, not #12. Not sure why Vans suggest #12 if the dimple die will not fit.

With regard to the below flush countersink. Even at .007 the counterweight sits a bit high. I assume this will pull flat against the web of the rib once the screws are tightened? Proseal will likley also help mitigate movement.

Thanks again!
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  #4  
Old 08-22-2021, 12:22 PM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,600
Default

Quote:
Originally Posted by RV701775 View Post
Thanks for the feedback. I will likley put a smear of pro-seal as well.

The #12 drill bit is 0.189", too big for a #10 die pilot. I contacted Cleaveland to check the pilot and they stated that "Our Die pilot is 0.1905 +- .00015 so 0.19035 to 0.19065" and suggested a #10 drill bit. This would require me to drill the hole to a #10, .1935 in for this to fit, not #12. Not sure why Vans suggest #12 if the dimple die will not fit.
I donít know why Cleveland has chosen to make the pilot of their die that diameterÖ I personally wouldnít make a hole bigger just because a tool didnít work using standard practice.
A #12 hole is standard for an AN509-10 screw. Dimpling in itself makes the hole diam. larger. That makes purposely doing so before dimpling, less than ideal.
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Hubbard, Oregon
Van's Aircraft Engineering Prototype Shop Manager
FAA/DAR
RV-6A (aka "Junkyard Special ")
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  #5  
Old 08-22-2021, 03:59 PM
RV701775 RV701775 is offline
 
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Location: Boston, MA
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Scott,

I see your point, but I just measured a Brown #10 screw dimple die and it has a pilot diameter of 0.193". So what is the solution here? If all of the tool manufacturer's make their pilots #10, what is the solution to dimple this hole?
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  #6  
Old 08-22-2021, 04:06 PM
mc607 mc607 is offline
 
Join Date: Apr 2014
Location: Canada
Posts: 67
Default

[quote=RV701775;1549984]Thanks for the feedback. I will likley put a smear of pro-seal as well.

Quote:
The #12 drill bit is 0.189", too big for a #10 die pilot. I contacted Cleaveland to check the pilot and they stated that "Our Die pilot is 0.1905 +- .00015 so 0.19035 to 0.19065" and suggested a #10 drill bit. This would require me to drill the hole to a #10, .1935 in for this to fit, not #12. Not sure why Vans suggest #12 if the dimple die will not fit.
I just tried my 509-10 in a drilled #12 hole and it went in but only after deburring the hole.

Quote:
With regard to the below flush countersink. Even at .007 the counterweight sits a bit high. I assume this will pull flat against the web of the rib once the screws are tightened? Proseal will likley also help mitigate movement.
Just so we're clear on the .007 below flush that vans refers to in section 5, it is meant for countersinks that will receive a dimpled skin. Like when you do your horizontal stabilizer and wing spars. It does not apply to all countersinks. Regarding my previous post I mentioned a micrometer. Meant to say digital caliper.
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  #7  
Old 08-22-2021, 09:40 PM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,600
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Quote:
Originally Posted by RV701775 View Post
Scott,

I see your point, but I just measured a Brown #10 screw dimple die and it has a pilot diameter of 0.193". So what is the solution here? If all of the tool manufacturer's make their pilots #10, what is the solution to dimple this hole?
I can't really comment on why tool sellers (or who ever makes the ones they sell) makes dies with the dimensions that they do.

All of the larger sized dies that we still use in our shop were made by Bob Avery, and purchased from the former Avery Tools. They fit a #12 hole.
#12 is has been spec'ed in the plans for decades.
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Hubbard, Oregon
Van's Aircraft Engineering Prototype Shop Manager
FAA/DAR
RV-6A (aka "Junkyard Special ")
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