Wood Gears

Looking for a practical use for an interesting mechanism, I decided to make wooden blinds for a window in my house.  As you can see in the video, the blinds are able to raise and lower by twisting the left handle to operate the crossed axis helical gears.  There is a spool on the back of the larger gear that winds up the two lines (50 lb. test monofilament fishing line).  There is a wood peg that aligns with holes drilled in the face of the smaller gear to act as a stop.  The other handle tilts the slats.  

Here's a view showing the spool on the back of the gear that winds up the lines that raise and lower the blinds.  The crossed axis helical gears have a lot of sliding action and the faces are lubricated by rubbing them with a bar of Ivory soap once in a while.  Some cars use helical gears in this manner in connecting the distributor to the camshaft.

The tilt adjustment is simply a dowel with two lines wrapped around it in opposite directions.  As one line is wound around the dowel, the other line is unwound by the same length.

The two lift lines are guided around a corner by a pair of pulleys that are tangent.  They also make the split to opposite sides as they come off the bottom pulley.

After making the split, the lift lines are routed over another small pulley, and then go through small holes drilled through each slat to the bottom bar where the ends are tied.

You can download a pdf file with the details of the window blinds.