How To Make A Knock Box

When a friend of mine found a La Pavoni at a garage sale and gifted it to me on my birthday, I took some birthday cash and headed straight out to pick up some espresso swag. I had to have a burr grinder, a tamper and a frothing pitcher. Then I stared at the knock boxes and couldn't do it. I could justify everything else, but dropping another $30-$50 on a knock box seemed like an insult. I'm not sure why. I suppose I just thought I could knock out the burning hot espresso grounds into the sink, garbage, etc. 

It only took about three failed attempts, the muddy espresso grounds all over the counter, my clothes, me, the cursing heard long and far...and then there was the digging for the basket of the portafilter in the garbage or compost. Some decisions just cause me to shake my head and wonder. Don't think I went back to the store and purchased the very thing that had already become the scapegoat of all daily problems. My stubbornness carried me to another level. I had to make my own...and cheaply. It took me a few days at work to stumble upon the answer. I was working at the cabinet shop when I noticed some 4 1/2" pvc pipe standing in a corner and for some reason my thoughts wandered to my ongoing coffee crisis. 

I began to rummage and ended up with the pvc pipe, a piece of 3/4" copper pipe and by extreme luck, a piece of sheet copper. I then had to go to the hardware store, where I picked up a piece of reinforced vinyl tubing. I think it was 3/4" in diameter. This is what I did: 

  1. Cut a 4" piece of the pvc pipe and sand the ends. Use medium grit sandpaper or a file.
  2. Measure down about 1" from one end of the pipe and again on the exact opposite side. Drill 3/4" holes with a spade bit or hole saw. Remove any pvc bits or burrs with file or sandpaper.
  3. Measure and cut the proper length of the 3/4" copper pipe. I had access to a pipe cutter (cheap ones can be had at a hardware store, $15 or less) or you could try a hack saw. Just make sure to sand the ends if you use a saw to remove any burrs. Insert into pvc pipe.
  4. Measure and cut a length of vinyl tubing. Make sure it fits tight from one side to the other, as this will help hold the copper pipe in place. Slit the tube once, lengthwise and place over copper pipe.
  5. Place the pvc pipe on your base (if you don't have sheet metal of some kind, find some plastic sheeting. I would avoid wood because of the moisture present in the grounds). Trace the outline of the pipe and cut your material. I used two-part epoxy to glue it on. I'm sure other adhesives would also work. Clamp it together or place something heavy on it to insure a good bond.

That is it! In hindsight, I may have looked for black ABS pipe. It might have looked better and would not have had the problem of looking quite coffee stained as parts of the pvc do. I think I might take mine apart and paint it. You may also be able to find a 4 1/2" "cap" piece which would eliminate the need for gluing on a base. Just make sure that the cap piece has a flat end as many are curved. As for durability, it has been amazing. Going on a year and a half now with no noticeable wear. Even the vinyl is holding up well. I think the one reinforced with string is quite strong. Good luck and let me know if you have any improvements or other materials that you prefer. 


Lawrence Black is a writer and editor at 
Simple, Good and Tasty.  He can be reached at