Steve Nelson's R2D2 Build History, Documentation and Archive

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HOME PAGE Mock Legs Glass Skirt Foot Work R2LA 10 Dome Work Sand Drive

Dome Work

While the second foot shell was curing, and after careful consideration, I decided to re-do my dome. At R2LA 10 I had the opportunity to examine a few pie panels and found that the only one I cut from my present dome was much too small for the accessories made by the club. I remember a trick from my aerospace days of laying up the panels first, then the dome around them. I began by scraping off the 35-year-old masking tape.
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I plugged the holes with Bondo and I washed off the dried tape residue and silver paint with acetone. Next I'll contour sand where the cutouts were and finish the dome as I would a pattern. I've got to decide wether to add the 2 rings between the dome and body now or add them later. I still need to make a tool for them and it may be easier to make them all at once. Or maybe not.
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The dome was the first piece I made back in 1978. I found a trash can with a rounded top and pulled 2 half molds off of it and joined them together. I wish I had that mold now.

I started to R&D some ways to make a glass dome look like aluminum. I can't find aluminum gelcoat on the Internet, or anything like it. I've called a bunch of places and all have no idea where I can look. Here is my first atempt with spray paint:
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Notice some of the paint didn't even stay dry after it was covered with polyester resin. Next I'll try and find some aluminum powder to mix into the resin. One of the group, Bjorn Danger, was kind enough to mention something called "cold casting" which I'm looking into right now!
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I filled in the pie-section cutout and the hole for the radar eye and sanded the dome to contour. Now it's ready for layout. I measured and drew a circle on a board I'll use for layout and discovered the dome is slightly irregular in shape. Too much work to fix it now, so will make a slightly irregular dome. There will be a small mis-match when the dome rotates, but only an engineer or another builder will notice.
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I found the most useful blueprints for my next step in the club Yahoo group file section. It was Curious Marc's layout in a .pdf file. I printed it out and taped it to the board and extended the lines marking the degrees of the cutouts on the dome. I made sure to note that since Marc is from Europe, he used metric degrees*, so being an American I had to convert them to inches. After marking all the cutout locations I cut the center out of the board so I have a way to attach the dome pattern to it from the inside.

*Note: You were supposed to laugh at that. I made that comment on the board and someone took it seriously.
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Now to make a flange about 2 inches high. I need space for the blue ring and the silver ring where the Rockler bearing will be located. Since I already had the basic shape in the skirt tool, I put a false bottom of cardboard and tape in the bottom and raised the sides with cardboard and tape.
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It was a quick layup of 2 ply of glass.
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I cut the ring at about 2 inches high and made the flange flat with Bondo on a piece of counter top.
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I centered the dome on top of the flange piece and tacked it together with Bondo, then I put 2 layers of glass on the inside to beef it up. Now it's not going to flex on me. Here's a shot of when I first started to fill in the 2" extension.
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Here's a closeup of the sweep tool I made. The sweep part is offset by 2 degrees draft so the part won't be mold locked, and the brace keeps it at 90 degrees to the surface.
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Fill and sand. Fill and sand. Fill and sand. Fill and sand. Fill and sand.
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I'll scribe the lines in for all the cutouts before making the new dome tool. I must thank Guy Vardaman for letting me trace one of his pie panels from an aluminum dome. I made a template and will get the pie panels close enough to fit the dome accessories.

The R2D2 Builders Club Yahoo Group: http://movies.groups.yahoo.com/group/r2builders/

HOME PAGE Mock Legs Glass Skirt Foot Work R2LA 10 Dome Work Sand Drive