Re: ATM Cutting aluminium rings.

[Fabio Pettinati <fabio@voreas.com>]

Marco,

You can use products called Alucobond, Dibond, or equivalent for use in 
the sign industry. You might have to glue two or more sheets together 
to get the thickness needed for the rigidity you want. In the US these 
sheets are available in 4ftx8ft sizes, although remnants are usually 
found in the waste room of companies that create signs.

The best (not necessarily unique) way to do what you want is to use a 
router. Use double-sided tape (carpet tape) to adhere a square of the 
material to a sacrificial plywood sheet, drill a hole where the center 
is supposed to be, and insert a pin where the router will pivot. You 
can cut the outside diameter first, followed by the inside diameter. 
Note that the router bit depth has to be just past the aluminum on the 
bottom. You don't want to cut too much of the plywood.

Alucobond is very easy to rout, and with my plunge Dewalt router and a 
spiral bit I had no problems cutting a good looking edge. You'll need 
to do some filing, sanding just to make things totally smooth. Before I 
forget, the exposed polyethylene edge doesn't take paint. Fortunately 
the edge color is black so it will look nice.

Hope this helps,

Fabio
San Jose, CA

On Monday, May 12, 2003, at 12:20  PM, Marco Miglionico wrote:

>
> Hello all.
>
> I'm working on a design for a new scope. (12.5in Dob). For the 
> secondary
> cage
> I am going to use the standard  2-ring cage. However, instead of
> 9mm ply for the rings, I want to use sandwich construction with 
> aluminium
> faces (0.7mm) and poly(somethingniceandlight) core all bonded together.
> The problem I am going to have though is how do I cut a 16in OD 14in ID
> ring(s) from 0.7mm thick sheet aluminium?
>
> The only thing I can think of,  is to jig-saw it out between thin 
> layers of
> wood
> while turning the piece on a bolt, which isn't ideal because the blade 
> never
> seems to want to stay vertical and perpendicular to the surface.
>
> Any better ideas?
>
> Thanks.
>
> Marco Miglionico.
>
>
>
>
>
>
>
>
>
>
>
>
>