Get yourself a suitable container such as a washing up bowl or plastic food container. Nothing too big, just big enough for the items to fit into. You can use an oven cleaner such as oven pride. It's cheaper to buy it from a discount shop such as home bargains/wilkinsons/poundstretcher. Costs £2.99.
Pour the contents of the bottle over the item. Within a few seconds you should see the crank start to fizz and the oven cleaner will turn white where it makes contact with the anno. Give it the occasional turn and rub with your fingers to remove any thicker and stubborn areas. Wear gloves. Regular washing up gloves will be fine. Once stripped, rinse the crank under the tap to remove any residue from the oven cleaner. You may need to give it a 2nd dunk to remove the last few bits of anno.
The 2nd way is to use caustic soda (again, the same shops sell it). Costs about a £1 for a small container, but i get the stuff in larger containers for about £15 from b&q.
This method is more dangerous, so i wouldn't advice doing it in your brand new kitchen. You must always wear gloves as caustic soda can cause nasty burns. Use the same container, and fill it with just enough water to cover the crank. Slowly add the caustic soda and give it a stir with a piece of wood or screwdriver. How much caustic soda you need will depend on the amount of water and the strength of the caustic you're using. You shouldn't need much, and you'll know when the concentration is right as the crank surface will start to fizz. Once the crank is stripped, rinse it in cold water to remove any excess. Do not leave anything in caustic for long periods as it will eat away the alloy over time. The left over caustic can be poured down the drain (as it's used as drain cleaner).
