[maxxgraphix]

How would you reverse cut text? Only cut out the material around the text. I know how to cut lines at different depts, but how do you remove a void? There must be a tool path to follow right? Also this would end up being many hours of machine time.

[skippy]

Gerry or Benny might better answer this than me BUT I would do about three outlines (offset) of the text by an amount suitable for your cutter size so that internal corners are still reasonably sharp (inside of "G" for example) then change to a big diameter cutter and just do straight lines to mill off what's left (assuming you're working in some kind of cad program). Use the biggest cutters you normally work with for the material you're cutting for the straight bit.
Skippy

[maxxgraphix]

That wouldn't work. The area is not just text and there is a lot of area to cut, 2ft x 3ft. There needs to be some kind of cut pattern in the dead areas. Plus it's HDU board.

[skippy]

I used to reverse engrave hardwood forestry signs from heavy beams about 2m x 0.4m high (sorry I can't convert to inches at 2.30am). this involved text, a logo and an external border and all we cut was the background. If you're not using a dedicated sign or engraving software you would outline (several times) text and logo and inline the border. For this I used 1/4" cutter. Next I would do the straight lines (left to right in my case) and stopping them where they intersected the the outlines of the 1/4" cutter. end of story. For me, 2ft x 3ft is not big. Of course, if on the computer you wanted to join up one horizontal line with the next below and so on in order to have a continuous tool path for the big cutter then go for it but it depends on how many of the same item you have to do in a run as to if it's worth it or not. In my case 3 outlines of a 1/4" cutter = 3/4" so a 1" cutter (= 1/2" radius) for the bulk removal was fine with no chance of touching the letter edges. Of course with an engraving or sign package, none of the above would be an issue.
"There needs to be some kind of cut pattern in the dead areas" Hopefully you just mean a toolpath to remove the waste material from the background and not that you have to cut some special pattern with two differing heights for example into the background (such as a crosshatch for example).
Skippy

[ger21]

What are you using to create the toolpaths? If your drawing them in a CAD program, I'd just draw lines back and forth. Offset the text, and use the offset to trim back the back and forth lines. Now if you need some type of pattern in the void areas, you'll either need to draw them in the CAD program, or invest in some sign software.