Questions and Learning from a New Builder...

[Derrick]

As I embark on this journey I thought I would create a thread/post to ask questions that I haven't found answers to yet...

I started my build and decided to begin with the .032 half ribs (ribs 3 and 4). I picked these for a few reasons.

1. When placing my order for aluminum sheet, the .025 was on order and hasn't arrived yet, the .032 has.
2. The flanges on the ribs don't have that much curvature, so bending them over should be a little easier (despite the thicker aluminum).
3. The size of the ribs is relatively small, so mistakes won't consume excessive amounts of materials (aluminum and MDF).

This brings me to my first question...

There are not any dimensions on the drawing specifying the length of the rib(s), so I am measuring and scaling... When I measure along the center line of the drawing I get 4.25" (doubling this because the scale is 1/2) gives me a line to line rib length... Do I make the ribs to this length, or do I make them a little shorter and allow the 90 degree flanges take up manufacturing tolerances?

[geraldmorrissey]

When confronted with issues like this I tend to make the part long and trim on assenbly. If you cut too short you may have scrap. Its tough to scrap a part thats primed and ready to install. It really sets you back. I'm living proof of that. I always try to cut the biggest parts first because if I screw it up I can make smaller parts out of them. Bob recommends not cutting ribs to final length to account for capstrip thickness before final assembly. A mistake can mean scrapping a lot of work or adding a ugly repair. Many have gotten away with it, some have regretted it. A good rule is "trim on assembly". This insures you get a part that fits per print. Its easier to make a part smaller then to make it bigger.
Gerry
Patrol #30

[Russellmn]

Or you could do my favorite and cut it three times and it's still too short!

[Derrick]

I was looking through the plans this afternoon and there is a slightly different cutout for the aft lightening hole on the center ribs 1 thru 5 (to clear the flap linkage assembly) than there is on the rest of the ribs...

Is there any reason that the lightening hole used in ribs 1 thru 5 couldn't be carried through the rest of the ribs to simply the build a little?

[geraldmorrissey]

I have learned not to second guess the designer. While the drawings look rudimentary, the design is well thought out. If you build per the print, you can reasonably expect a certain level of performance and stuctural integrity. Be creative, change the windows, the fairings, the instrument panel, but build the structure per print.
Cheers
Gerry
Patrol #30