Stepper Motor Controlled Windows

This was an oft worked on, but never finished project whose end goal was to build windows which opened, closed and locked by control of stepper motors coupled to each individual window pane. They may not be roboticized nor entirely finished, but they are still beautiful functional windows. They swing open and closed with ease and inspire many other unique home made window designs (I hope).

The window frames are made from smooth finished 1×2’s (1×3’s?) grooved out on one side with the groove bit from a tongue and groove router bit set. This groove is where the glass will be fitted. The grooved pieces are cut to size and mitered so that four fit together to form a tall rectangle; each being half of a window that opens at center.

The glass pieces are all thin single panes I recovered from old cabin windows around my neighborhood. I cut the glass using one of those little red $2 glass cutters from home depot. You can see it on the right of the second and fourth pictures above. Mark the glass clearly where you want it cut and run the wheel of the cutter very firmly down that line. After scoring, put a dowel under your line and press gently on both sides of the glass where you want it to break and you will get a clean snap.

Measure twice cut once. The windows are made from thirty two wood pieces. Sixteen short, sixteen long, four windows, eight panes. I start with two perfectly cut pieces, one long and one short then used these to trace the remaining pieces.

The pieces are glued together at their miters and the grooves are filled with silicone to seal the glass panes in to place. I used a piece of OSB to make a jig for gluing together four window panes at a time. I built the windows in place on top of each other as pictured, gluing them as I went. I screwed a long piece of wood on the bottom and right side for aligning and supporting the windows as they were put together. Once I had four windows built I screwed two additional pieces on the left and the top to press the windows together and make tight joints.

Before putting the windows together I pre-drilled one hole in each short piece. After putting the panes together I used a self-centering doweling jig to open these holes up to accept steel dowels which serve as the pivot for the windows to open and close as well as where the stepper motors would couple to control the windows. You can see these dowels cut to size by angle grinder in the following set of photos.

I used a chamfer bit to carve chamfers on the dowel side of each pane, seen in the third picture above. This allows me to set the panes as close to the window frame as possible without the edges hitting the window frame as they open and close. After chamfering and sanding I taped off the glass to prep for painting.

Two coats of white kilz wood paint leaves the panes weather sealed and ready for the next step.

I used JB Weld to seal stacks of quarter inch washers around the holes where the dowels are to be inserted; both on the panes themselves and the window frames. This gave me a surface to balance the windows and apply oil for them to open and close smoothly.

I dumped JB Weld into the holes in the window panes where the dowels go to make sure they never shift out of place. This was an entirely unnecessary step and a waste of good JB Weld.

The old windows and window casings are pulled out to leave a flat open window frame. Washers are applied and stacked tall enough to keep the panes tightly in their positions. The washers are lubricated and I fit the panes; lining up the washers mounted on each pane with the washers mounted on the sills. One metal dowel is hammered in from the bottom and one from the top. The bottom dowel is hammered all the way flush with the sill and the top is left extending from the top sill to allow the eventual coupling of a stepper motor.

Had this project been completed I would have installed new window casings to create an air tight seal when the windows are closed. I had also made a block of wood (first picture above), bored out through its center to allow room for a motor coupling (see here). The stepper motor would be mounted on top of the block and the bottom of the block would be sealed to the window top sill around each pane’s dowel.

I was able to test the concept with one Nema17 stepper motor and an appropriate driver board on one window pane and it worked very well. Regrettably my final design was never put together, but you can see my beautiful windows in their current state in the pictures above.