Tips for Cutting Aluminum



Cutting Alclad by Chris Ruble (cruble@cisco.com)

There was a discussion on cutting Alclad without getting distortion on the edges a while back. I would like to share my technique. In the past, I have cut sheets with hand shears, starting about 3/8" from the line and sneeking up (narrow strips) on the last part followed by alot of careful file work. This works well but is time consuming.

After deciding to install single piece top skins I ordered .032 Alclad from...well I forget the name of the company...you know, the add has the lady standing in a roll of Alclad. Anyway...they ship the stuff in the full 48" width any length you want. I ordered two 9' sections and planed on having them sheared locally. After the local sheetmetal shops did a lot of grumbling and made alot of excuses about the tolerances and my desire to not have the material scratched I decided to make the cuts myself. I was not looking forward to making 18' of cut on $170.00 + of material with the handshear method.

After pondering several alternate methods I had and idea...how about a router ( no not the kind that Cisco makes ) a wood router. I grabbed a scrap of Alclad and clamped a straight edge to it, installed 1/8" HSS router bit and... WOW!!! The router cuts through .032 like butter and makes an edge that needs only light (very light) fileing to clean up. This works so good, and is so easy I don't know why it isn't common practice. I found that the best edge is produced if you keep the router moving quickly (your mileage my differ). Try this...you'll love the results! I think that this method could be used to cut the hinge notches in the control surfaces if a larger bit were used. I have not calculated the surface speed of the bit yet but I would guess that a 1/4" bit will start pushing the envelope. Perhaps a carbide bit would be needed. Also the .016 material may need to be solidly clamped. I mentioned the method to my father, who is a retired aircraft engineer, and he tells me that the window holes in the L-1011 were cut with a router in 3/8" skins! If this method is good enough for Lockheed, it's good enough for me.



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