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Building Tips and technical articles. => Building techniques => Topic started by: Garf on July 12, 2010, 02:21:26 PM
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I am going to have to use plans to make ribs. This is the one part I have never been able to do from prints. I always break the balsa at some point. What is the best method of making intricate parts in balsa from prints?
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Everyone has their own method.
If the ribs are regularly spaced in the wing then stack cutting them works well. Make tip and root templates out of something hard (aluminum, linoleum, or 1/16" aircraft plywood), and bolt a bunch of balsa blanks between them. Then take a really sharp knife and whittle down the stack to meet the templates. You probably want to finish up with a nice rigid sanding block.
If you're building on a jig use the jig holes for the bolt holes, and use brass tubing to hold the ribs in proper alignment.
Done right this will put in all appropriate spar notches, and will only have the drawback that each rib edge will be slanted too much -- on most wing buildups you can fix this after you get the spars, leading edges and trailing edges in place by lightly sanding everything straight.
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It has also been recommended that you use those ribs as patterns to cut the final ribs with no taper! If you use really hard balsa (or even cardboard!) this is not impractical.
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I always make photocopies of the ribs and bulkheads, then roughly cut out the paper copies and stick them to the balsa with 3M photomount, cut the rib out accurately then peel off the copy, then stack the ribs, sand them and cut spar slots etc. Works well every time, even with a tapered wing.
Cheers Neville
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Hi All, I have used a dress maker's wheel, carbon paper, tag stock(a/k/a poster board) to make close to exact copies of all plan parts. First put the tag stock down, thencarbon paper, then plan over the carbon paper, tee or push pin this sandwich down on your board. Run the wheel around and the carbon paper will outline all parts on the tag stock. Cut out with an ExCTO BLADE OR FINE QUALITY SISSORS TO produce reusable patterns. Put in envelope to preserve for repairs or another copy of the same plane's parts!
Tally Ho,
Phil Spillman
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I always make photocopies of the ribs and bulkheads, then roughly cut out the paper copies and stick them to the balsa with 3M photomount, cut the rib out accurately then peel off the copy, then stack the ribs, sand them and cut spar slots etc. Works well every time, even with a tapered wing.
Cheers Neville
This has always been my method as well, but I do one more thing, I mark a centerline on each template, then I cut the rib long and wide at the trailing edge, The trailing edges always seem to be where they get them wrong. So with the oversized rib and a corresponding CL on the trailing edge, I avoid the low spots and short ribs that ocurr.
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I'm just about to return to the stack method, after about 40 years! the plan I have shows only the the root and tip rib. Last time I did this I used some formica for the templates, can you still get formica? Failing that I'll use thin aluminium (sorry, English spelling! alu-mini-um) and my Dremel scroll saw.
Cheers Neville
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I'm just about to return to the stack method, after about 40 years! the plan I have shows only the the root and tip rib. Last time I did this I used some formica for the templates, can you still get formica? Failing that I'll use thin aluminium (sorry, English spelling! alu-mini-um) and my Dremel scroll saw.
Cheers Neville
Well, for straight or tappered wings I stack too.
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This wing has quite a taper, its Ray Browns 1959 Geisha Girl, same wing as used on the Koy Kat and Koy Lady. The trouble with using metal for templates, is that knocks the edge of your scalpel or plane blade if your not careful.
Cheers Neville