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Welding Airframe Sequence

1934A, the overall idea is to start with a flat table and then build it in the upright position from there. They recommend beginning with the firewall sub assembly and then drawing and using reference lines on the flat table to assemble from there. The key is to have a fixed reference lines and work from there. Also, assembly may be done in halves.

Cleaning - Wipe off any excess oil or protective coating from the outside and inside of the tube. Use a Scotch-Brite pad to remove and expose bare metal. Wipe with acetone. (I'll have to give this a try. I've had the best finish with a 120 grit flap disk but haven't tried Scoth-Brite.)

Welding - VR3 is pretty clear, their tubes are notched to fit well. A gap indicates a mistake with assembly and should be addressed. Tack welds to hold as much structure as possible together. This allows you to confirm assembly and dimensions prior to final welding.

Like with all things, I get the impression that time spent on preparation and ensuring accurate measurements from the start on the table will be time very well spent. I imagine I'm going to spend a fair amount of time just setting up my assembly welding table. Since my work space is used for other things I'll probably build it on casters so that I can move it to the side. Fundamentally it must be rigid.
 
Aeronut, Did they tell you to work from the bottom up? Or was there any mention of making two identical sides and then joining them together?

I've never done one from scratch and likely won't. But I have thought that making the two identical sides first would give more accurate results.

It seems to me, working from the bottom up would provide more possibilities of a twisted result.
 
Skywagon, they explicitly state not to. "Do not build the sides as flat sub-assemblies because the tube kits have the profiles, pre-formed longerons and other tubes based on the final 3D geometry." They seem to take pride in their notching which is designed to all fit snuggly together and provide additional weld support. I interpret their literature to mean that they designed it with a specific assembly method in mind. Perhaps it wouldn't mattter on another assembly, but on this companies it looks like it does.

Edit to add more info from their literature:

"2. Build the kit “vertical up” in it’s normal flying position:a. Helps avoid confusion about left hand/ right hand orientations
b. It may be tempting to build the structure relative to an alternate ‘flat’ surface or
upside down. Do not be fooled as this will lead to confusion as the assembly progresses."
 
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There is a guy that built a Skyote using a VR3 kit. Lots of pictures how he built his jigs on his website. Granted, lots smaller than a Cub, but same idea.

Skyoteblog.blogspot.com


Sent from my iPhone using Tapatalk
 
I got an email yesterday from VR3 and, in keeping with their customer service, Don VanRaay sent me a detailed document laying out how an assembler should approach welding the fuselage together.

Nice! Glad that worked out. Very much interested in their document, always learning.
Also...That Lincoln TIG 200 is a great little machine, portable, light, handy. Glad you’re happy with it.

Thanks for for the additional info they provided. Clarifies some things.

Cheers, Oz
 
Take lots of pictures, and keep us posted on your progress! This sounds like a great kit, their workmanship sounds top-notch! I'm excited to watch it come together.
 
I'll be following too. I love watching others' projects while I slog along on my own.
 
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