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  #1  
Old 09-08-2018, 04:23 AM
OrenAir OrenAir is offline
 
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Location: Chantilly, VA
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Default Math problem?

In the horizontal stab attach bar, page 10-04, I'm having math trouble.

The top left figure says the piece is 5 and 13/16 wide. The bottom says it's the sum of 1 and 3/16, 1 and 1/4, 1, 1 and 1/4, and 1 and 3/16. I add those up and get 5 and 14/16.

Millimeters don't work for me either. Top view says 147.6 mm. Bottom says sum of 29.8, 31.8, 25.3, 31.8 and 29.8. My calculator says that's 148.5.

What mistake did I make? Is it the difference because the back side is angled, and the top is measuring the back while the bottom is measuring the front?
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  #2  
Old 09-08-2018, 04:42 AM
mturnerb mturnerb is offline
 
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I think your math is correct but it's pretty hard to be that precise when making this part. I started from the center and used the template as drawn as a guide. (comparing my marks on part to drawing as well as the part as I took material away to get to the final version). It came out "close enough".

You're talking about 1/32" on each side of center difference on a hand made part. If you could get it that precise, I'd say err on the side of caution and spot Van's the 1/32" - make the top of the bar 1/32" wider on each side.
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Last edited by mturnerb : 09-08-2018 at 05:03 AM.
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  #3  
Old 09-08-2018, 05:28 AM
OrenAir OrenAir is offline
 
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What piece does it connect with? I want to make sure it fits great before riveting.
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  #4  
Old 09-08-2018, 05:46 AM
Reflex Reflex is offline
 
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It rivets to F-01411E and F-01414 which rivets to the main side longeron (page 10-27 figure 1). The "3-sided notch" or cut out is so that the bolts that hold on the elevator bearing (page 8-03 figure 2) will clear.

If the piece is too long, it will stick out over the F-01414 deck. Not a big deal as you'd never see it. However, the 5 13/16 measurement works perfectly. If you're +/- 1/32", you'll be fine.
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  #5  
Old 09-08-2018, 06:09 AM
mturnerb mturnerb is offline
 
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All the rivet holes are already in the piece. Clearance is not that critical (having already built this part and test fitted the HS) - if within 1/32" no issue at all.
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  #6  
Old 09-08-2018, 08:13 AM
OrenAir OrenAir is offline
 
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Awesome. Thanks for your help. :-)
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  #7  
Old 09-08-2018, 02:20 PM
StressedOut StressedOut is offline
 
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Slightly off topic, but still related. I am not a fan of fractional dimensions. It's easier to make math mistakes. I wish Vans would stop using them and go to decimal.

I have a friend who occasionally helps on my build who also happens to be a machinist with his own milling machine. He is going to put the F-01411D on his milling machine and CNC machine it down to final dimensions.
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  #8  
Old 09-08-2018, 05:16 PM
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RV-14E RV-14E is offline
 
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Excellent catch!

As long as you follow the taper of the aft deck, I suspect you'll be fine.



Do your best and go to town.





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