Leave the worms alone. What you want to do will not help them.

The smaller the worm bin the harder it is to keep the worms happy and healthy. Stay with the bigger one. You will better food, heat, oxygen and moisture control.

To get at the castings faster, and leave the worms in the 55% still to be done I do the following.
Get 5 gallon round bucket, plastic childs easter basket wtih 1/2 inch by 2 inch or so holes with handle that will fit in the bucket, mine is rectangular. Put basket into the bottom of the bucket. Take a plastic container or can and fill it with wormes and compost. I use a tri claw hand tool for this. Dump this into the easter basket. Take the easter basket and twist it around like a ride at the amusement park. The vermicastings and finer vermicompost and what ever worms want to jump ship will fall into the bucket. The larger vermicompost and homebody worms can be dumped into a second bucket. Repeat. This will quickly fill the first and second bucket. When you bin is empty, refill with the contents of the second bucket. In a few days many of the worms will be at the bottom of the first bucket. The dryer top layers can be put into the coffee cans for a month or so for the eggs to hatch. The worm filled lowest layer can be dumped back on top of your bin. Your coffee cans will then contain your most finished vermicompost with a lot of vermicastings.

I agree. Leave 'em alone. Small bins are more susceptible to various problems. The larger mass of compost/bedding allows space for the worms to move away from potential problem areas. If one corner becomes anaerobic or something toxic accidentally develops there, the worms can retreat to the other parts of the bin.

If you want to harvest in small batches, you could try putting small batches of material in a colander or some shallow tray with holes in the bottom. Put this on top of your compost and scoop a small amount into it. As it dries out, the worms would exit through the bottom holes back into the main compost. If your bin is open (no lid) even a little light will also drive them downwards. Check back in a few days and the VC in the tray should be relatively worm free. You still have to check for cocoons or you could just send them into your garden to hatch and amend the soil there.

If you want to experiment with a small worm bin, get a CLEAR container (1 gal. or less) and fill it halfway with torn cardboard (soaked overnight first) and some decaying leaves. Poke some air holes and throw in a handful of compost with worms & cocoons from your main bin. Put the whole container in a cardboard box. Take a peek when you get the itch to dig around in your main worm bin. Feed very small amounts of already rotting food. The bedding will feed the small colony for a very long time, so you don't really need to feed them for some time.

Andrew

I agree - not worth the bother - unless you have kids and want to give them their own mini bin.