We rarely use regular compost any more. After we build a pile we let it work for 6-8 weeks then we feed the partially decomposed ingredients to our worms to finish the job. We use the worm castings as the main ingredient in our seed starting mix and we use them as a topdressing when we move transplants into the garden.
Our worm bins are modeled on Will Allen's bins at Growing Power. They are made of non-pressure treated 2 x 12's. They measure approximately 2' x 3' x 19" deep. We have 12 of them. We place about 6" of the partially composted material in the bottom of the bin then add about 5 lbs of worms. Then we fill the bins with more compost until it is bulging up over the top of the bin. As the worms consume the material gasses are given off and the pile shrinks about 30%. It takes about 60 days for the worms to completely eat the whole pile.
After they finish a bin we lure them out and move them to a fresh bin to start the process again. When Will described how they get the worms out of the bins i could not believe it would work until i did it for myself. What we do is lay a piece of window screen over the bin and spread about 3" of fresh compost over the screen. The worms are hungry and living in their own poop so they squeeze through the tiny holes in the screen to get to the fresh food. I know, hard to believe :) As they do this the contents of their gullets get squeezed out of them leaving a very fine layer of beautiful castings on the top of the pile under the screen.
We leave the screen on for a week, dump the worms and repeat 2 more times to get all the worms out. At first i thought that the last worms to come out were probably slackers but now i am of the opinion that they must be the most hard core worms because they were able to tolerate being in the bin with little food and surrounded by poop for the longest time!
After the worms have been removed we let the castings dry out for a couple of months before we use it. We push it through a 1/4 inch screen to remove the rough stuff which makes for some mighty fine castings. We collect the bits of woody material that has not completely broken down and use them to mulch our fruit trees. It is already inoculated with fungus so continues to break down and feed the trees. From each bin we end up with about 150 lbs. of screened worm castings.
We love our little worker worms!