Using a step drill bit for this project ensures perfectly round holes that are mostly free of burrs.

Parts:

Modifying an existing aluminum or stainless kettle by adding a valve, thermometer, and hop/trub straining screen is not so difficult, and it’s cheaper than buying a new kettle with the upgrades included. Just imagine feeding your counterflow chiller by simply opening a valve. No more siphoning boiling wort!

Use a step drill bit for this project, although a hole saw (for the 7/8-inch hole) and 1⁄2-inch twist bit will suffice. The step drill (Fig. 1) will be easier to use and makes perfectly round, clean holes that are mostly free of burrs.
For this project, we’ll be using weldless kettle fittings. This means we’re going to need to drill some holes in the kettle. Drilling metal doesn’t have to difficult ... if you have a few essential tools. Here’s what you’ll need:

Weldless Fittings:

The drilling can be difficult, but the fittings are very easy to install. You’ll need the following:

Measure Twice, Drill Once:

Find the kettle center point and draw a line top to bottom. Make two drilling marks — one for the thermometer and one for the spigot.

To have the valve and thermometer face 90 degrees from the handles, use a tape measure to find the distance between the kettle’s two handles, divide by 2 to find the half-way point, and mark it with a Sharpie or grease pencil. Draw a line from the mark down to the bottom of the kettle.

Make one mark on the line about 1.5 in. (3.8 cm) up from the bottom of the kettle and another about 7 in. (18 cm) or higher from the bottom (Fig. 2).

The top mark is for the thermometer, which, according to the manufacturer, should be at least 6 in. (15 cm) from the kettle bottom to protect it from the heat of propane burners.

Drilling: Aluminum:

For aluminum, the easier of the two materials to work with (by far), common dish detergent is an excellent drill lubricant. Apply a small amount to the areas on the kettles marked for drilling. Also rub some detergent on the drill bits for good measure. It’s a good idea to pre-drill a small pilot hole to get things started (Fig. 3). The smallest hole size on the 7⁄8-inch step drill is 3⁄16 inch, so begin here for the pilot hole. Drill a pilot hole on both marks.

Next, use the step drill to widen the pilot holes to their proper sizes. The bottom hole for the valve should be 7⁄8 inch (Fig. 4).

Use the step drill to widen the pilot holes to their appropriate sizes.

The top hole for the thermometer should be 1⁄2 inch, which is the fifth step on the step drill. Keep drilling until you feel the bit drop down five times. It’s a good idea to check the diameter of the hole every couple of steps to make sure the hole doesn’t get too big — there are no do-overs.

It is a good idea to pre-drill a small hole to get things started, before switching to the step drill bit.

use a metal file to smooth the edges and remove any sharp burrs. A Dremel Tool with the appropriate metal grinding bit also works well. The holes should be smooth inside and out to prevent burrs from damaging the rubber gaskets used in the weldless fittings. Wash the kettle inside and out to remove any lubricant.

Installing the Ball Valve

Remove the brass nut and rubber gasket from the weldless bulkhead fitting. (Note: the bulkhead comes with two rubber gaskets, but only one is used in installation — the other’s a spare). From the inside, put the bulkhead’s threaded pipe nipple through the bottom hole. The metal washer should be on the inside. On the outside push the rubber gasket over the pipe nipple and then hand-tighten the brass nut until both it and the gasket are flush with the exterior kettle wall (Fig. 6).

Hand tighten the brass nut until it and the gasket are flush with the kettle wall.

Installing the Thermometer:

First, calibrate the thermometer following the manufacturer’s instructions.  The Blichmann Brewmometer dial reads from 60–220 °F (16–104 °C) with several important brewing temperatures marked, making it ideal for use for both boiling wort and mashing and sparging grain (Fig. 8).

Finished Project