title_body: Avoid clumps in finely ground coffee
upvoted_answer: I wouldn't go so far as to say that it's not a very high-quality grinder, it does extremely well for the price. The clumping is an artifact of:
  
  
  Humidity
  Heat from grinding
  Type and roast of the bean
  
  
  Grinders that produce almost no heat while grinding, to the point that they do it reliably enough for it to be a listed feature cost ten times the amount that you paid for your grinder. Heat during grind isn't an indication of a low-quality grinder, rather, little to no heat is simply an indicator of a very high-quality grinder. There isn't much you can do about this other than purchase a manual burr grinder and grind by hand very gingerly, which takes lots of time.
  
  Tamping alone should be sufficient to deal with any clumps (at approximately 15kg of force) - if it's not, then you want to take a very close look at the beans you're using, and the level of humidity they're exposed to in storage. Is your grinder normally close to anything that produces steam? Is your kitchen air really humid? Are the beans stored in air-tight containers? If you have clumps that tamping won't take care of, you probably have a moisture problem.
  
  It can also be the bean, some roasts just do not do well for espresso, no matter how fine the grind or how dry the storage. 
  
  Both Lavazza and Illy produce a very pleasant medium arabica bean that should work very well in your grinder. They are very consistent in production, delicious, and should give you a good baseline to select other beans that would work similarly well. You can get beans that weren't specifically produced with espresso in mind to work, but it takes a bit of tinkering. I recommend the above beans very often to people just getting started because they're delicious and very easy to work with.
  
  Anyway, try one of those, see what comes out of the grinder. If you're still getting clumps that don't immediately break down when you tamp (tap the portafilter on the sides a few times before you tamp to help this) you could try cleaning the grinder, changing how you store the beans, or looking at a de-humidifier in the area that you keep them.