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  #11  
Old 11-03-2017, 10:44 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by Tacco View Post
Thanks guys.

I think Paul had it right the first time though. The holes in the roll bar and window were already "final drilled" to #36 in step 2. By "Final drill #27 the remaining #30 holes" in Step 6, I'm pretty sure it means the ones in the aft turtle deck skin and window in that area. Since they are #30. The ones associated with the roll bar were never drilled to #30 anyway. At least that my interpretation of the english.

All that said, here is an indication that Scott may be right with respect to Van's intent - the drawing, Fig. 2 25A-04, seems to show enlarged smooth holes in both areas of the window.
Sometimes describing processes with written words can be challenging.
Drilling 40 and then FINAL drilling was in the context of the tapping process (since the process was started with a smaller hole, 36 is the final drilled hole for TAPPING.
Once the tapping process is completed and the window is no longer being used for the tapping process, the holes are final drilled for attachment with screws.

In this particular case the term final drill during the initial drilling is more meant to describe a process (drilling holes in multiple steps) than it is to mean that is the final finished size for the hole.

A lot of instruction steps are written in the context of expecting the builder to read through the entire section (and gain some understanding of what is to be done) before beginning, as described in Section 5 of the manual. If they are looked at from that viewpoint, many steps make more sense than if taken sentence by sentence by them selves.
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  #12  
Old 11-04-2017, 01:00 AM
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pstraub pstraub is offline
 
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Thanks for the clarification Scott, that makes sense. I have not sealed my rear window yet, so the next time I have it off, I will final drill those tapped holes in the plexiglass. I think that I would add 5 words to pg 25A-03, Step 6 to make it a little more clear to future builders, but I am probably one of the few that didn't figure it out!

"Final-Drill #27 the remaining #30 holes and the previously tapped holes in the F-1277B Aft Window."
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  #13  
Old 11-04-2017, 08:58 AM
Tacco Tacco is offline
 
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Reading through this entire section to understand the context, is precisely what I'm doing. Haven't even taken the window down off the shelf yet. When the plans say "Final-Drill #27 the remaining #30 holes holes in the F-1277B Aft Window.", to assume that this also includes the holes that were previously drilled to #36 and tapped, is exactly that - an assumption. Nothing in the plans leads to that assumption, step by step or in total context. ....with the possible exception of Figure 2 on page 25A-04.

The plans are pretty good, having been vetted by so many builders thus far. I've learned to trust them. Every time I think it would make sense to deviate, I've been proven wrong.

Yes, is doesn't seem logical that you would leave them tapped. But, I also don't think tapping them in the first place seems logical. I can tap a straight screw hole in the roll bar and see no reason to risk running a tap through the window and then screwing a screw into it!....but that's what the plans say so there has to be a reason(?).

Let's see what the experts/authors say on Monday. I'm not in any hurry. But I bet they agree with Paul - the plans are unclear on this point....whether taken step by step or in total context. And there is nothing challenging about Paul's suggested clarification.
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  #14  
Old 11-04-2017, 09:40 AM
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rongawer rongawer is offline
 
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Default Good discussion

This is the kind of discussion I enjoy reading, especially regarding the kit plans, processes, and the perspectives of how different folks see things.

For the window installation, just keep in mind the purpose of the different drill steps is to ensure that the hole through the window is aligned with the hole in the structure (perpendicularly), and then to ensure that there is sufficient clearance around the fasteners for the window to move as it expands, contracts (at different rates than the aluminum structure and fasteners) and reacts to airframe movement.

1. Initial drill, which is your pilot hole to ensure proper hole placement.
2. Final drill of the structure for tapping size, which is also through the window, used to ensure proper alignment of the tap.
3. Final drill of the window, which ensures fastener clearance.

A tip for installing plastic windows is that once the final holes are drilled, then go back and chamfer the window holes on both the inside and outside; I recommend a rounded end, fine grit stone on a dremel at slow speed removing just enough material to do the job - don’t overdo it. As Scott point out, truss head screws are used, so countersinking is not the goal, but rather rounding of the hole openings to stress relieve the material and minimize potential cracks.
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  #15  
Old 11-04-2017, 11:20 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by Tacco View Post

Let's see what the experts/authors say on Monday.
Well, I avoid the title expert, but I am one of the authors, but go ahead and see what one of the tech support guys say.......

In the context of different wording..... The nemesis of technical writers is that no matter how you write it, there will be some people that don't understand, but would have if it was worded differently. That doesn't imply lack of anything on their part... just that everyone has there own way of understanding and sometimes it falls outside of the way something is written......
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  #16  
Old 11-04-2017, 11:31 AM
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rongawer rongawer is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
Well, I avoid the title expert, but I am one of the authors, but go ahead and see what one of the tech support guys say.......

In the context of different wording..... The nemesis of technical writers is that no matter how you write it, there will be some people that don't understand, but would have if it was worded differently. That doesn't imply lack of anything on their part... just that everyone has there own way of understanding and sometimes it falls outside of the way something is written......
Scott, while I truly appreciate your advice, I caution you that when you say things such as the above, the tag line you use “Any opinions expressed in this message are my own and not necessarily those of my employer.” will likely provide little relief for Van’s in a litigation process as you are no longer expressing an opinion as an independent forum participant, but rather using your position as an employee to emphasize the credibility of your advice. That’s for free...
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  #17  
Old 11-04-2017, 11:42 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by rongawer View Post
Scott, while I truly appreciate your advice, I caution you that when you say things such as the above, the tag line you use ďAny opinions expressed in this message are my own and not necessarily those of my employer.Ē will likely provide little relief for Vanís in a litigation process as you are no longer expressing an opinion as an independent forum participant, but rather using your position as an employee to emphasize the credibility of your advice. Thatís for free...
It is not for litigation protection, it is to emphasize that any info received through official channels that contradicts my info, should take precedence (and that is why I said to go ahead and check with tech support if he didn't feel comfortable with my answer).
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  #18  
Old 11-04-2017, 01:50 PM
Tacco Tacco is offline
 
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Thanks guys. This is a good discussion. Gleaning the experience and expertise of others is exactly why I come here and what makes this forum valuable. Remember that why I asked this question initially was that I suspected leaving the holes tapped was not appropriate. It was not a question of my understanding of the plans, its an issue of what the plans say, and in this case, do not say. The plans simply do not say to drill out the forward window hols to #27. What is a matter of understanding is Scott's knowledge of the intent. I do not have his understanding of that intent (which Ron describes beautifully above).

Scott, now that you've self identified as one of the authors, I may have lots of questions!!
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  #19  
Old 11-04-2017, 02:55 PM
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Tony_T Tony_T is offline
 
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I had to replace my Lexan window some time ago and upon doing the replacement I used a uni-bit to enlarge the holes. The plans called for enlarging the holes to #27 but I could not source a #27 drill bit for plastic. I was not unhappy as my experience was plastic drill bits can cause cracking even when you are extremely careful. With the Uni-bit the nearest size was 5/32, a bit larger than #27 but I figured that was a plus. The Uni-bit makes a very smooth hole in Lexan with NO cracking.

Note the black painted edge.
A caveat, this was for the Lexan and may not even be pertinent for the newer plexiglass rear window. I would be interested to know if others have used a Uni-bit in plexiglass.

Another RV-12 builder, Randy, did something similar making oversize holes and using a thin slice of rubber tubing as a kind of O-ring in the hole for the screw. I thought that was a neat idea.
http://www.rv12.pflanzer-aviation.com/finishkit09.htm

Another neat trick I learned from Randy's website was to paint a black edge on the part of the window where the sealant would be injected to make a smooth black line when viewed from the inside:
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  #20  
Old 11-04-2017, 05:07 PM
DHeal DHeal is offline
 
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Unibit worked great on my Lexan rear window as well. It has the added advantage of nicely chamfering the edge of the hole -- use a careful touch. It also produces a slightly larger hole which in my mind gives a bit more room for screw/Lexan expansion. Practice on scraps first to build your confidence.
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