lml@lancaironline.net Mailing List Archive

<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> I originally thought that paying $250 or so (per side) for a CNC-cut aluminum instrument panel was too pricey, so I started doing it myself. Now I know better and think $250 is cheap. However, I'm most of the way through the process, and I thought I'd pass on some lessons learned. 1) I'm using 0.063 aluminum for the panel blank. It's pretty sturdy, but you end up cutting most of it away, so there's probably not much need to try and get by with 0.040 inch for lightness. 2) If you can get precut blanks, do it. I couldn't, since I have the old-style 360 panel with the eyeball vents and the slanted circuit breaker sub-panel. 3) If you buy a 2x4 foot sheet of aluminum, as I did, go to a local sheet metal shop and have them shear it to approximate size. They charged me $3 and I gave them a 5. (When I came back to get another piece sheared for a second attempt, it was free...) It's much easier to deal with when its small. For that matter, you can probably get the material AT the sheet metal shop. They were surprised that I brought my own. 4) Put a new sharp blade in your bandsaw. Put a new piece of sandpaper on your belt sander. Don't even think of using hand tools for this. Cut close to the line and sand right up to the line. Now you have a blank panel. 5) The surface that rests on the belt sander table will get horribly scratched. I'm putting a teak veneer overlay on (today's plan, anyway) so this doesn't matter to me. It might to you. 6) You will notice that the bottom of the fiberglass panel is not perpendicular to the protruding radio stack. This is probably not a problem for those of you with the flat panel. 7) Pick a horizontal base line. Whether it's parallel to the bottom or perpendicular to the side is not important. Draw the line with a FINE-POINT Sharpie marker. Have the line about an inch from the bottom. 8) Clamp a steel ruler or straightedge to the base line. I used those Cleco side-grip clamps and it was very easy. Use this base line to draw with. A 90 degree angle is required -- it can be a plastic obne from the office supply store or a steel carpenter's square -- it doesn't matter. 9) Measure out where you want the hole centers to be. Draw them in with the fine-point Sharpie. Use the straight edges to finish the layout from the measured points. 10) You DO have a 2-1/4 and 3-1/8 punch, don't you? If not, get one and come back later. These are about $100 - $110 at the aircraft tool stores, reversible to do either size. 11) Here's an important one, and the main reason I had to do it over. Don't just draw the hole centers. Draw the complete hole circle. This is best done by cutting out an instrument hole from a piece of scrap metal. Take the sample hole and use it to draw the actual instrument holes on your panel. Make sure you have enough edge distance for instrument mounting holes (or you'll be sorry, as I was...) 12) At this point you have the hole centers and all you have to do it cut the holes. The rest is up to you. By the way, does anyone know how to cut square holes? I did one using a Dremel fiberglass cutoff wheel but it was slow and I had to stop frequently to wipe water on the panel to cool it off. Came out well, though. Maybe I should buy a sharp new blade for my coping saw.... - Rob Wolf [When I laid out all the aluminum for the various brackets required for my LNC2 I purchased a spray can of blue layout die and used an inexpensive dial caliper to do all my measurements. This is not news to those of you who have machinist experience, but when I saw it done for the first time I was truly impressed. If you use the tips of the inside-measuring jaws you can actually layout to the nearest 0.001". Those tips are needle sharp and provide really nice fine silver lines in the blue dye which to follow. Try it, you'll like it. <Marv> ] LML website: http://www.olsusa.com/Users/Mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com.