LettersFromFlyoverCountry

LettersFromFlyoverCountry

Well Known Member
In all of my studying and research in advance of putting the canopy frame/rollbar together, I neglected an obvious discrepancy which I only realized today.

I have three 631A-L and three 631A-R channels. As near as I can tell from the plans, I need two each. and the instruction process refers to assembling one pair and then refers to what to do with "the other pair." That's 4.

What's the extra one of each for? What am I missing?
 
Cabin Frame

They go on the aft end of the tip up canopy....sorta like stiffiners for the plexiglass I guess. They'll line-up with the cabin frame.

Sam
BTW..sounds like I'm at abut the same point as you...maybe?
 
7A_@ABI said:
They go on the aft end of the tip up canopy....sorta like stiffiners for the plexiglass I guess. They'll line-up with the cabin frame.

Sam
BTW..sounds like I'm at abut the same point as you...maybe?
Click to expand...
Ah, I see. thanks.

Yes, you may be at the same point as me. Many, many, many people here have been at one time or another... in the same way that a Porsche is at the same point as a Yugo on the way to blowing its doors off. I am of the Yugo persuasion. :D

I'll get there. Eventually.
 
Now, that I've completed the studying/research for the canopy frame fitting phase, I think I've figured out a weakness in the procedures that potentially could result in poor fitting frame. But I don't know.

I've taken a piece of MDF and layed out a bottom line, the 42 5/19" points with vertical lines at each end and a vertical centerline and a top horizontal line, perpendicular, of course, to the bottom line, and this would be 17 19/32 (I can't quite recall the measurement called out on the plans).

I lined up the bottom outside side of the left aft channel with the intersection of the outside vertical line and the bottom horizontal line, and lined up the top center edge of the channel with the top horizontal line and measured how much should come off the top end to match the vertical centerline.

Then I did the same with the other side's channel and noticed the measurements don't match. A quick mating (mirror) of the two parts revealed that one channel was 2/32" longer than the other.

Now according to the directions, and a lot of people's Web sites as near as I can tell, what you normally would seem to do is lay the channels out along the bottom line, establish the 42 5/32" boundaries, measure the discrepancy, divide by 2, and then cut that much off the top center of each channel.

But if the two channels were not the same length to begin with, that potentially could move the exact midpoint of the entire structure left or right, and wouldn't that create a poor fit somewhere because your unit is no longer symmetrical?

I also notice some of the channel cuts at the factor, aren't exactly square to the flanges.
This, for me, is a case of measure 20 times, cut once. I'm just noodling this through and seeing if I'm missing anything.
 
While you want everything to be as symmetrical as practical, don't be too anal because, guess what, the canopy isn't symmetrical either! I discovered this when I was painting my canopy.
Mel...DAR
 
More Cabin Frame Stuff

Bob,

I'm in the middle of the cabin frame thing. It's assembled now and am fittng the two angle brackets....studying the exact placement on the fuse, etc.
Here are a couple of pics of how I clamped the frame to the table. This setup worked pretty well. With the channels clamped down, I tapped the flanges with a hammer to get as nearly to 90 deg. with the web. As much as I tried to maintain the original measured width of the fuse, the frame ended-up 1/8" narrower. This seems to a be common problem. It looks like some (including Checkoway) were able to "pull" the bow out when bolting it up to the brackets/fuse. When I made my frame, I stood it up verticle & measured from two like points from each side down to the table. This let me know if one leg was longer than the other...both were equal and the top of the frame was parallel to the table top. I used a piece of .063 as a "height gauge" to measure up on each leg, the amount to trim off. I circumscribed the line & then used the belt sander to trim to proper length. I think I ended up trimming off about 1/8" or so off of each leg to get the right height. Yours may differ.
Hope this helps.

Sam

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Thanks, Sam, it will help a lot.

You know, it's really something when you can take a bunch of advice from a number of people -- each with their own perspective -- and put it all together to achieve a desired result.

I've gotten up to the point where I'm ready to drill the bottom strap. The one thing I learned from most people was make SURE the strap is well seated i the channel. So today I used a Vixen file to treat the outside edge, then used the plans to measure how much of the strap sits above the flange (11/16") and drew a line along the strap and then refitted it and used the line to double-check that it was well seated.

I also remembered Dan Checkoway's advice to "flange the hell" out of the channels. Even if you do that before fitting the strap, I still found areas where they could've been flanged better once I fit the strap. So I removed the strap, "reflanged" and proceeded along.

On Sunday, I bought $50 worth of C-clamps (using my $5 Ace rewards card and a $5 sale copupon. Hey timing is everything when you're on a small margin!). The 2" clamps were used to hold the channels vertically and horizontally using the idea on Matthew Brandes' site. The 1" clamps and the Cleco clamps hold the strap securely in place (Ken Scott advice: You can naver have enough c-clamps)

clamped_for_drilling.jpg

By also having the measurement points clearly marked on the MBF, I can check constantly (as is : whenever I do anything) to be sure the structure isn't bending, bowing, or twisting out of alignment.

So far, so good, although I realize it's early in the process. But thanks to those willing to share their experiences, I'm pretty sure I know where the "gotchas" are hiding and can plan accordingly.
 
Part 731F has gone missing in my workshop. It's the spacer at the rear
of the channel that connects the cabin frame to the 706 bulkhead (tip-
up). Looks like it's just a piece of aluminum. The dimenions of which
I can get from DWG 20 and it looks like it's backdrilled using the
channel as a guide.

But I can't see any reference to what thickness the material is.

Does anyone have the part handy and, if so, can you take caliper to it
and tell me the thickness. Maybe I have a piece of scrap around here
somewhere I can use.

There's no such part listed on the Van's Web site.
 
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