In the past Ive used an industrial Crest brand ultrasonic cleaner, what I found is that the ultrasonic cleaner will produce very slight frosting to highly polished parts if left in too long, that caused me problems.
What I use now is a cheap crock pot filled with a mixture of TSP and water. Put parts in crock pot, crank it up to high, and a few hours later all parts are clean. An added benefit, parts left in a TSP solution tend not to rust, Ive had parts in the solution for over a month..no rust. TSP will not harm CCH or bluing.
Crock pots can be had very inexpensively from thrift and second hand stores, set up several, one for nasty cleaning, another for lighter cleaning then a third with oil for a hot oil dip of the parts.
