Instead of using acetone go to your local Shopper's Drug Mart and get a bottle of 99% isopropyl alcohol, otherwise known as rubbing alcohol. Make sure you get the 99% pure; if they don't have it then 91% is the next best.
Save your stems till you have a lot. Cut them up into small pieces, about an inch or couple inches long. Then soak them in the iso for about 3 or four minutes.
Filter out the stem material. Then let the iso evaporate at room temperature (less dangerous this way), or heat low and slow on a stove (quite dangerous: use double boiler method). Use a large, flat baking sheet for evaporating because it will evaporate faster with the large surface area, plus you will have to scrape the hash off. Sometimes it can be quite hard.
After the iso has evaporated away you will have what will likely be the best oil/hash you ever smoked. :jointsmile: