Since I seem to be able to get the K40 to cut and engrave satisfactorily, it is time to start improving it.
The exhaust system for the K40 has some quirks to contend with. Somewhere I read that an owner thought that the K40 unit was designed for engraving primarily rubber stamps due to its small working area.
One of those quirks about the machine is that the exhaust funnel extends about 1/2" into the cutting area effectively reducing the work area the same. This is a picture of the exhaust funnel from the inside of the machine. the masking tape show where I will trim it. It will need to be shortened about 3/4". It is fortunately a relatively easy solution. I originally thought that the funnel unit was welded in permanently and it would be using an angle grinder inside of it to cut it short but I simply removed the funnel by unscrewing the four mounting screws in the back of the machine. There were some complications though, as I needed to remove the x-y axis and the cutting bed as well. At first I was a bit intimidated, but determined that it was only maybe a dozen screws to remove.
Here is the result. I did my cutting with a metal cut off saw and resulted in a pretty clean cut. I did some fine tuning with a belt sander and Dremel. The usit slipped back into the laser housing, and the cutting bed and X-Y axis was reinstalled. I was a little afraid that the X-Y axis might be out of adjustment, but testing after showed that it was functioning fine.