No More Coffee Grounds in the Cup

Our Mr. Coffee 4-cup drip coffeemaker left grounds in the brewed coffee when no one monitored it during brewing. I found a simple way to slow the flow of water into the basket so coffee can drip out of the basket speedily enough that the basket does not fill with water and overrun the top of the filter. Other coffeemakers may have the same problem and this Instructable may be useful for owners of them.

Materials

1. 6-32 x 5/8 or 3/4 brass screw

Tools

1. Drill
2. Drill bit
3. 6-32 tap and handle
4. Ruler

I made a measure for ground coffee that holds 1 3/4 Tablespoons when level full. We place 2 1/2 measures of ground coffee into the paper filter. That amounts to 4.375 Tablespoons of fresh ground coffee. More ground coffee per brewing will make it necessary to slow water flow even more to avoid the overflow of coffee grounds.

Follow this link for an Instructable on how to use linear measurements to make a container for accurate volume measure.

My plan involved partially blocking the water delivery arm to slow the rate at which water enters the basket holding the coffee filter and grounds. I placed a brass machine screw across the water channel inside the pivoting arm. I located the hole so it would be above the basket in case of any leaks. Hot water would still fall into the basket if there were a leak. I had a 5/8 inch screw in my screw cabinet. The water delivery arm is a little bit wedge-shaped. Where the screw is located impacts the length of screw needed. If I were making a special trip to the hardware store, I would get a stainless steel screw an inch in length.

I drilled the hole a little small so I could use a thread tap to thread the hole. That makes the screw position adjustable. The drill bit was not as long as I would have liked, so I swung the arm toward the rear of the coffeemaker to be sure the drill bit would be long enough.

The tap is also barely long enough, but I succeeded in threading the hole for a 6-32 screw.

Turn the screw into the threaded hole. See the first photo. Begin to brew a pot of coffee. Watch to see if the basket fills too quickly and is in danger of overflowing. Adjust the screw as necessary to regulate the balance between the rate at which water comes into the basket and coffee flows out into the carafe. In the case of our coffeemaker, a 5/8 inch screw turned fully inward works quite well.

A word of caution: The arm that delivers the hot water to the basket is made of two pieces snapped together. It is easy to turn a screw too far inward and push the far side of the arm apart so that a seam opens. In time the pieces of the arm will conform to the pressure and too much water comes into the basket. If that happens, you can attempt repair with a heat gun and a hot glue gun to close the seam again.

This photo shows how high the water was during brewing. It came near to the top of the filter, but had a small reserve that kept water from overflowing and carrying coffee grounds over the filter and into the carafe. This modification does not require more time to brew a carafe of coffee, but it does eliminate the need to monitor the coffeemaker during brewing.