- About the 701
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Other Good Stuff:
- Rib Routing
- Rib Forming
There's a very quick and easy method of cutting out ribs and other such parts from aluminum sheet. It uses an electric router with a laminate trimming bit. I've heard that this method has been used at DeHavilland Aircraft to mass produce parts for their aircraft. Gary Wolf has demonstrated this technique at RAA seminars and other aviation events in southern Ontario.
The router follows a wooden form, cutting the aluminum sheet flush with the edge. Each rib is individually cut - although you might be tempted to stack up a few sheets and cut them all at once this turns out to not be a good idea. The cutter tends to get loaded with aluminum and the sheets get welded together. The story goes that DeHavilland used to bond the edges of laminated aluminum sheet in just such a way.
The method is so quick, however, that it doesn't really take that much longer to cut the ribs out individually.
Any woodworking router should work. Bits, on the other hand, can make the difference between success and failure. One thing you may find surprising is that the cost of the bit seems to have little to do with how well it cuts sheet aluminum. Gary has had the best results with an inexpensive Mastercraft cutter that he purchased from Canadian Tire (see Fig. 2). Other more expensive types that he has tried did not work as well. The best advice would be to try different makes until you find one that works well for you. Another factor that may affect results is the type of aluminum you are using. Gary used 6061-T6 for the demonstration.
As many of us know, woodworking power tools can be used on aluminum provided that the cutting speed can be slowed down. This is often done on bandsaws, for example - pulley systems can be used to reduce the speed while maintaining torque. This doesn't apply to routers, though. Using an electronic speed control you can reduce the speed of the router but you also reduce the torque, and you will find that you don't have enough power to cut the aluminum.
You'll need to develop a feel for cutting the sheet while the router runs at its normal speed. Too slow and you'll have a mess. Too fast and you have a mess. Best to practice first. Fortunately it doesn't take long to get the correct feel of how quickly to move the router so that the chips clear the cutter properly.
Here's how it's done: