DRILLING FOR AN3 BOLTS QUESTION

General Everything Else
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I’m building a SonexB. I’m working on the Main Spar of the Vertical Stabilizer, On page SNB-T09, the plans call for AN3 bolts. Now I see I should drill these using a #12 bit. The pre-drilled holes are #40 size, so should I just drill these to #12 size or should I enlarge them gradually, e.g., # 30, # 20 #15, then # 12?

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Al,

I would never go right to final size. Better to drill up in steps. AN3 bolts are 3/16. I would typically go up by cleco size - #40, #30, #21, 3/16”. Your hole will be more round.

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Hi Al and welcome to the forum!

You’re going to get all kinds of answers to this one. John Monett used to tell us you’re not building a Swiss watch, yet you will find people who updrill then ream to final size….

Me? I used drill bits but did not go in such small increments. Your mileage may vary…but I sure get your FOFU….I did that a lot (FU) and just learned it is part of the process…

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It would be best to step up in stages.

#30 you probably have clecos for so that would be a good choice. #13 is slightly smaller diameter (.1850") than 3/16 (.1875")so that would be a good size to finish with, I think the 3/16 clecos should work for that.

#12 is slightly larger diameter (.1890") than 3/16" so if the # 13 is too tight (it most likely will be an interference fit which is ok), maybe use 3/16 instead of #12.

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That’s what I was thinking; I will just need to buy #21 and do it this way.

Thanks again, Bryan.

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6

yep

12 = .1890”; 3/16” .1850 inches & 13= .1850 inches. Thanks, Murray. How’s your Waiex doing?

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Hi Robbie,

Yup - most of the advice I’ve gotten is quite helpful. And I’m frequently trying to get over the overthinkin’ it hump telling myself ‘You’re not building a space ship!!’ Don’t let the perfect be the enemy of the good!

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No, but good practices, asking good questions, and following the plans goes a long way!

Enjoy the build and we look forward to seeing your progress!

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Thanks for asking Al.

I finally got all the parts and will start the process of getting it back to better than before condition. Probably be a couple of months to do it all and also will need the annual inspection done too.

I made the stupid mistake of removing the gear/engine mount and now have no great way to support it while doing all the work. Hoping to put the new mount on over the next few weeks.