Chris,
My Wells Index also had one of those Bijur mist units on it. I also had problems with the bacterial growth in the coolant, and so on. It was quite a lot of work to maintain their system. It would spray all right when cleaned up, but if it sat for a week or so, it would get a skin growing, which could then gum up the works.
I went with a small submersible pump for flood cooling when milling and drilling steel with HSS. Just ran the whole system out of a plastic 5 gallon bucket, with a return hose from the table to the pail. This simplified cleanup issues somewhat. Flood coolant is quite messy on an open machine, though.
Milling steel with carbide is probably better done dry. Roughing operations using insert cutters can give a pretty good finish right off the tool, but size control is a bit more difficult with inserted tools, in a quill type machine spindle. I used 3/8 up to 3/4" Iscar insert endmills in my Wells with adequate results. The small insert endmills only have one insert, so this can make for slow going, although the feedrate can be fairly aggressive. Finish cuts with solid carbide endmills are preferable for good side wall appearance, but the results produced by the end of the tool flutes was often hit or miss, quality wise. If you never plunge with the tool, and never recut old chips, and thus preserve the extreme corners of the flutes, then you stand a good chance of getting a good finish on the bottom of a pocket.
I went with a Trico air-lube unit for milling aluminum. For the material removal rate of a small machine, I think the Trico unit is entirely adequate for aluminum, and finishing steel, but it does require an air compressor running quite often to provide even its relatively modest air requirements. It is not noisy, does lubricate the tool nicely to assist in the finish cut, and get the chips out of the cut zone.
The finish produced by the end of an endmill depends on the quality of the grind. I do not think any tool will cut without leaving the swirly finish, but an accurately ground tool should produce a finish that is not snaggy to the fingernail. Some guys set up a brush operation to refinish the surface to a uniform appearance. Some kind of light duty sandblast or tumbling operation might be the answer to complex surface finishing. Those all tend to remove the shine, but at least everything looks about the same.
Iscar makes special inserts for cutting aluminum, with a wiper edge and polished face. The finish produced by the end of the insert tool is superb. It needs lots of rpm though, so probably the 3/4" tool is near the minimum you can use on that machine, running full speed, and still get the good finish.
First you get good, then you get fast. Then grouchiness sets in.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)