In this instructable you will learn how to repurpose an old cordless drill to motorize a slider window so that it can be operated by a person who is too short to reach the window latch or does not have enough strength to reach and push the window pane.
Cordless drills are easy to buy used. Their batteries deteriorate after a few years and oftentimes, owners prefer to buy a new one rather than invest in new batteries.

You will need:

- A cordless drill with a battery charger.

- A 3/8" threaded rod (from the Home Depot)

- Bondo car body filler (Home Depot)

- Spray paint

- Momentary DPDT (double-pole double throw) switch from RadioShack (item 275-0709)

- 16-14 ga quick disconnect from O'Reillly

Assorted hardware (screws, nuts and bolts)

Step 1: Remove the Trigger and Switch

Remove the drill's handle, the on/off button and the forward/reverse switch. You can either take the drill apart or just cut them out with an angle grinder.

Step 2: Install a Connector for the Motor

Choose a connector to power the drill. I salvaged one from a laptop's power brick; apparently this kind of connector is called IEC 60320 C7. Cut a notch in the side of the drill and flatten it on a belt sander. The C7 connector has a groove around the perimeter and it should slide tightly into the notch. The previous step will have exposed the motor's contacts - solder them to the connector. If you are using a reversible connector, you do not have to worry about the polarity.

Step 3: Prepare the Charger

Take apart the drill's battery charger and locate a large capacitor: this is where you are going to draw the current. The charger has other circuitry downstream of the capacitor to ensure the battery follows the proper charging regime, but you will not need it.

Make an extra hole or notch in the housing for the cable that will run to the drill. Slide a piece of heat-shrink tubing on the cable for strain relief. Attach the two wires from the drill motor in the middle of the DPDT switch. Solder two wires on each side of the capacitor (four wires total) and attach them on either side of the switch so that in one position, the plus of the power supply is connected to the minus of the motor and in the other position, the plus of the power supply is connected to the plus of the motor. In the neutral position, nothing is connected and the motor is not running. Connect everything together and verify that the motor turns one direction with the switch to the left and the other direction with the switch to the right.

Print a plug for the battery slot on a 3D printer and mount the switch on it.

Step 4: Make a Window Attachment

The part attached to the window can be as simple as a steel angle screwed to the window pane. If you cannot or do not want to make holes in the window pane, then you will want to slide something over the window handle. In my case, the "handle" was a strip of PVC plastic running the height of the window pane with a lollipop profile. Cut two halves of the profile on a table saw out of laminate flooring scraps and add an extra groove for excess glue (see picture). Using large-size paper binder clips, verify that the two halves fit snugly enough around the window handle.

Cut a piece of piece of steel plate ~ 1/8" thick. Drill a hole 5/6" in diameter and thread it using a 3/8x16 tap. If you do not have a steady hand (or an eye for plumb), you can use the tap in a drill press and turn the chuck with the key manually back and forth. Make a corresponding larger hole on the two boards.

On a table saw, make a series of blind cuts on the two boards to make space for the steel plate. Check that it slides freely in and out and that the holes align. Take the plate out and glue the two halves together using 5 minute epoxy while holding the two halves together with binder clips or clamps. Make sure to remove any glue from the groove by sliding a length of string in it. Use some thin tool to clear out the slot for the steel plate if needed.

Step 5: Bondo, Paint and Assembly

Use several coats of 3M Bondo (car body filler ) to sculpt the handle area into a smooth paintable surface. Take all the screws out. Using masking tape and a sacrificial plug to protect the electrical connection, spray paint the whole drill as well as the window attachment. Make sure to use an appropriate paint in a well-ventilated area (Rust-Oleum Paint & Primer in One from the Home Depot works fine). When the pain has dried, reattach all the screws except the one at the base.

Cut a board out of wood or a similar product the size of a window sill. 3D-print a bracket to attach the base of the drill to the board. Use a long screw with some plastic spacers to attach the bracket to the drill.

Install the threaded rod in the chuck and measure its offset and elevation. Using a jigsaw, cut a support piece for the far end of the rod out of a scrap of hardwood. Glue the part in place with a biscuit if you have a biscuit joiner.

Step 6: Installation

Thread the end of the rod into the window plate.

Remove sliding the window pane

Slide the window plate onto the window handle.

Lay the motor assembly on the window pane.

Install the window pane with the window plate on.

Slide the window to position the end of the rod inside the drill chuck.

Tighten the chuck.

P.S. One week later

The most common critical comment I hear is that this window opener is too slow, and I agree. This problem has a very simple solution since the Makita is a two-speed drill and it has been running on low. Unfortunately, the way I mounted the drill, the speed selector that you can see in a photo in step 5 ended up on the underside of the drill. I 3D-printed a wheel to make speed change easier and switched it to high gear. Here are the videos of the mechanism in high gear - opening and closing.