Shaping Aluminum

[Doug Mason]

I'm running a 1 inch wide aluminum bar as a guide in a router jig (MDF) templete that will allow me to cut slots. The slot in which the aluminum bar runs has a rounded end from the 1 inch straight router bit. Instead of squaring the rounded slot in the MDF jig to fit the squared end on the aluminum bar, I want to round the end of the aluminum bar to fit the end of the slot. What is the best way to round-over the aluminum to get a clost fit? I tried a jigsaw and file--but it was sloppy. I was then thinking of using a carbided tipped router bit and jig to round it off? Anyone have any idea's on a good method of doing this?

[Jamie Buxton]

You can use carbide router bits to cut aluminum. The downsides are that it wears the carbide quickly, and that it is messy. Aluminum "sawdust", if not cleaned up, will skratch the wood in your next project. Instead, I'd use the wood tools to shape the wood meet the aluminum, instead of vice versa.

[Bruce Page]

Doug, if I understand your question correctly, you want to shape the Al bar as pictured. I would just scribe a line using a divider or a 1” diameter washer and sand it on the belt/disc sander. If you take your time, you can get it very close.

[Gary Keedwell]

I would go with belt sander and file it smooth. Using carbide or even HSS steel on aluminum will not dull your bit, but think it is overkill.

Gary K.

[Cliff Rohrabacher]

Take a file to it. A #2 mill file will give you a real nice finish and let you manage the stock removal very precisely.
A Trak sander is fast and works great.

I have machined Alum with a router before. It's a frustrating experience as routers are not millers and even though it works and you can do it it's noisy, ya gotta take real shallow cuts, and the router bits are not made for Aluminum.

[Frank Chaffee]

Doug,
I agree with those who suggest you do gross stock removal with some sanding or grinding machine.

That ½” radius is far, far too tight to cut with a jigsaw, but several cuts tangent to the arc would remove most extraneous material.

Regardless of the method you choose, stop removal short of a scribe line and finish to the line with a file. I advise finishing with a file because you will then be able to align your eye squarely to the work surface, whereas with most powered grinding machines this is more difficult. Also note that most alloys of aluminum gall and tend to produce a substantial burr along the line of grinding.

In metalworking, the file is among the most revered of neander tools. Apprentices of old practiced cutting metal for long hours with dull, worn-out files in the workplaces of their hoped for future employment.

Today, we have access to very high quality files. A good file is as pleasurable in use on metal as fine planes and scrapers are on wood. When I use a file, I do not rub it back and forth over the material I am cutting, but rather, cut on the push stroke, clean the chips from the teeth with a swipe along my blue jean or leather clad thigh, and take another stroke. To remove more deeply embedded metal chips from the file, use a file card frequently.

Frank Chaffee