Air Nibbler to Rough Out Lightening Holes Prior to Routing

[SpruceForest]

Probably old hat and covered in numbers vids, etc., but if roughing out lightening holes with a fly cutter seems daunting, and tin snips is a little tough on the smaller nose rib and aileron and flap blanks, an air nibbler does a quick job of removing the material to within a 3/16" or so of the finished edge, and at minimal risk (eye protection for flying chips).

I load the drilled rib blank in the routing template/rout cover sandwich, step outside (nibblers make a terrible mess), use a 1/4-7/8 step drill to punch a starter hole near one edge, then use the edge of the router template as the guide for the nibbler. Without that 1/4" hole from the fly cutter, I can even get a couple aileron and flap rib attachment angles out of each piece of the larger hole's scrap. Having the rib blank held in the router template/cover sandwich makes drilling fast and easy, while the edges of the template guide the nibbler cut to within a easily-routed-off margin (no deep routs in wide material).

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DISCLAIMER: Yes - totally doable with with tin snips, fly cutter, CNC, etc. Pick the best option for your situation and available tools, but if you have a $23 Harbor Freight air nibbler handy and are already routing the ribs, it works.

[alaskabearhawk]

Those little half-moon snips are nasty sharp. Hope you don't have any animals!

[geraldmorrissey]

I fly cut most larger holes. People shun fly cutters as too dangerous. Clamp the stock properly, brush cutting fluid on the stock, set the proper speed on the drill press, make sure the cutter is sharp, don all safety equipnent and cut away. Once your through, minimum cleanup and your done. I've never had a problem with them because I take all the safety precautions. I have friends that did not. "Gimmi four beers" as he holds up three fingers and a stump. Looks like great progress. Thanks for the nibble cutter tip.
Gerry
Patrol No Title

[rodsmith]

I've used a fly cutter extensively on my project. As you state the stock has to be properly clamped. Like using a lathe, you have to stay focused, no daydreaming.

[SpruceForest]

In about a week. that whole area gets scraped down 6", gravel, sand, and pavers, but will def tell the crew to be careful!

[Glenn Patterson]

In hindsight the fastest way to do the lightening holes would be to use a hole saw about an inch in the center of the rib. Use a bearing template to zip around the inside of the lightening hole with the rib in the template. I would recommend doing the lightening holes after the ribs are flanged to avoid any unusual distortion. Knowing what I know now it would have been fast cutting the holes on the router table.

[Glenn Patterson]

Actually drill the hole for the router bit closer to the edge of the lightening hole. That will allow the router bit get to its final path with less cutting. The router bit bearing can follow the template and the cut disc will fall clean