[tmarks11]

I don't see why I can't do the same thing with 36" inch sections on the smaller machines.

If you look at the Novakon Torus Pro, I suspect that you will find it is not really much smaller than you knee mill with a table of 40x12".

?????? I'm not casting anything. I'm machining a 4 inch wide and 120 inch long profile INTO steel or aluminum.

The confusion comes from your calling this a steel mold. Generally you pour something into the mold and cast it. Most people assume that a mold is a one-off creation, and a majority of the production work is done with casting the product. It sounds in your case that machining the extrusion IS all of the production work.

Is this a one time production, or do you foresee making a lot of these? If you are making these over and over, than you should probably think seriously about the Haas TM2, since the increased horsepower and increased X-travel will help over time. Used TM2s sell for about $22-24k for mid-2000's models (without tool changer).

One real advantage to doing these on a open bed mill (like the Haas TM2 or Torus Pro or Tormach) instead of your existing knee mill is that you could set it up with roller tables on both side, and machine the entire 10' section in one go, with just sliding it and re-clamping it on the table as you finished machining each 18-24-40" section (depending on what machine you ended up with). A well built jig would be needed to make sure you keep alignment between cutting sections.

As long as we are pouring time and money down a rabbit hole: cnc X-Y table with 15k spindle mounted on a moving gantry that can cut the extrusion all in one setup. Make the table 12" wide and 10' long, and it should be plenty rigid enough for machining aluminum. Down-side: can only make one type of thing.