[eljainc]

Hello,

I need some guidance here:

We want to undertake cutting a curved shape into a 4" x 4" piece of aluminum plate, thickness of 1/2"

The piece will look similar to this:





Our radius needs to be 12.5", again the piece is 4" square, 1/2" thick.

We have a homebuilt CNC XYZ router which we have successfully cut plexiglass and other plastics, but this is our first real foray into aluminum.
We have a bosch 1/2 HP router.
We have ordered from ENCO some 2 flute special purpose aluminum cutting, 1/4" and 1/2" diameter ball nose endmills.

I have talked with one person who gave me some general advise on fabrication:

1. Keep your RPMs of the router somewhere in the middle (too low will drag the tool into the metal, too high will generate excessive heat).
2. If need be, keep the material cool with an alcohol mist (70% isopropyl)
3. 10/1000ths to 30/30000ths material per pass maximum
4. 20"/min feed speed maximum
5. Careful handling the tools, keep them sharp

The software I use to run the XYZ router table is DeskCNC.

What software can I use to design this part? DeskCNC can create all of the toolpaths, etc, but I'm at a little of a loss on how I can set up the
part in a CAD, then generate the G-Code.

Thanks for any help on this seemingly simple part.

Thanks
Mike




Except for the

[awerby]

You should be able to make this part in any 3D software package that will generate an STL file. Try Cubify Design if you can't make one of the free programs work for you. I'd agree with the recommendations you got, except you need lubrication as well as cooling for aluminum, or it will stick to the cutters. Give yourself some margin on the outside of your piece to hold onto, and cut it to size afterwards. You need to hold it down really well, or the pressure of cutting will move the workpiece. And use a hardened aluminum alloy for this, like a 6061 T6. Softer alloys are harder to cut because they tend to gum up the cutter, which will then break.

[eljainc]

Andrew,

Thanks for the post.

I feel like a real newbie here. I tried a web based 3D software designer called 3dtin (3DTin)
It has a real simple CAD interface. Now, I have to figure out how to lay this out. I am struggling a little bit
I guess with this as I'm not even sure where to start. I know I need a curved volume subtracted from the
block of aluminum, but I don't know how to specify that in the CAD.

Any help please?
Thanks
Mike

[awerby]

Does that program have boolean operations? If so, you can do it that way, building a block and a cylinder and then subtracting the cylinder from the block. If not, see if you can construct the edge profile in 2D and extrude it 4 inches. This will require you to make a rectangle 1/2" x 4" and a circle with a 12.5" radius, moving the circle so that it hits the corners of the rectangle, then trimming away the excess line on top and the rest of the circle that doesn't intersect the rectangle.