Building a Glass Crusher

DISCLAIMER: This page documents what we did, but we’re not suggesting that you should do anything like it. This machine can cause severe bodily harm, and if you use this information to build anything then you assume full responsibility for the consequences.

We converted an old clothes dryer into a crusher for crushing glass down to pieces small enough for making countertops. The basic idea is to drill holes in the drum so the broken pieces can fall through, and to make an opening the bottom so they can fall into a bucket below the dryer.

October 3, 2009
The first step was to remove the top and front of the dryer, and then to add some reinforcements to the side of the case. This is a view looking downward, with the dryer laying on its back. The drive belt runs around the middle of the drum and the motor sits behind that, so we decided to put a vertical “fence” made of plywood below the middle of the drum and to enable the crushed glass to fall out in front of that. The fence sits in front of the 2x4s shown in this photo. We added some slanted plywood sides to make a “funnel” that will guide the broken glass to the middle, where we cut a hole in the bottom of the case. Notice the plastic fins inside the drum. These are fine for tossing clothes around but they’ll quickly get smashed once this is full of bottles and rocks so they have to go.

Once we had cut the 8-inch-square hole in the bottom of the dryer and boxed around it with plywood, Dave drilled 5/8″ holes in the drum so the crushed glass can fall through and out the bottom.

We replaced the flimsy plastic fins with square steel channels bolted on to the drum. For the first short test we put in just a few bottles plus a fist-size rock to help smash them up. These photos show the glass before and after running for a minute or so. It works pretty well for a first try!

October 5, 2009
After a few test runs we decided that the holes needed enlarging from 5/8″ to 3/4″, in order to let slightly larger pieces of glass fall through. We also added another steel bar for a total of 4 bars instead of three, arranged symmetrically around the drum. The most significant refinement was to remove the heater from the back of the dryer, leaving an oval opening near the top of the drum large enough to feed bottles in while the crusher is running. Now we don’t have to stop it except to empty the glass bucket at the bottom when it’s full (it holds about 40 pounds of crushed glass).

In addition to letting us feed glass in while the crusher is running, the opening in the back of the dryer allows us to watch the crushing process – and so can you! The following is a video shot through the port on the back of the dryer as the crusher is running. For a realistic sound effect while watching the video, turn your computer’s speakers to maximum volume and then repeatedly slam them together as hard as you can right in front of your ear. It’s louder than that.

In our first production run it produced 70 pounds of crushed glass in about 15 minutes. That may sound like a lot, but our countertops will be about 85% glass and weigh about 18.5 pounds per square foot, so 70 pounds of glass will make roughly a 2-foot by 2-foot section of countertop. We’re going to need a lot more glass! Here’s a shot of the crushed glass we produced, with a dime added for scale. This is all clear glass, but you can see that some of it has light shades of blue and green. The pieces range from dime-sized down to dust, which will make stronger concrete than if the pieces were all of the same size.