Curtain pulls are best when they are perfectly matched to the curtain and the window. Curtain pulls are often cheaply made and badly designed, and since they are usually designed to be adjusted to different positions and heights, they tend to have a lot of parts and break easily.

In my case, I had a curtain on a three-section window in my kitchen, and the type of curtain we had installed used a simple (and cheap) plastic piece to hold the bottom of the string. The plastic piece was designed to be screwed into the window frame. However, with the three-section window, the middle section had nowhere for the plastic piece to screw into, so the pull string was left hanging.

So I designed a curtain pull tensioner that screws into the windowsill and keeps the pull string under light tension with a spring that can be purchased at a hardware store or online. The tensioner can be customized to the height of the curtain pull using the OpenSCAD source file.

I don't know how useful this will be to others, but it seems like the sort of general-purpose household item that other people could make use of. If you make one, please let me know!

MakerGear

MakerGear M2

Doesn't Matter

Doesn't Matter

0.3

50%

A high-strength filament like ABS, PET, or PC will work best, but PLA should work okay.

The part is designed to be printed in halves and glued together using a pin alignment method. Each part (with the exception of the sleeve) has alignment holes sized for use with 1.75mm filament. Stick the end of the filament into the hole on one of the pieces and cut to a length of about 4mm or so, so that the filament acts as a peg. Then fit the two pieces together, clamp them tight, and glue. For PET, I use methylene chloride (aka Weld-On #4) to glue.

The axles can be printed, but I used lengths of 1/4" diameter aluminum rod purchased at Home Depot, cut to the width of the piece.

The springs can be purchased from Home Depot, Everbilt extension springs 5/8" x 3-1/4" x .072" (1.6cm x 8.3cm x 1.8mm).

Attach the base with four #6 x 1" flat head Phillips wood screws.

Attach the bottom side of the spring last. Before attaching the spring, slide the sleeve onto the part with the pulley, and slide it up. Then attach the spring to the base, and let the sleeve drop down to cover the spring.

The OpenSCAD file has two main parameters, the pulley diameter and the height of the pull string above the windowsill. Chances are that the pulley diameter doesn't need to be changed, but you will want to adjust the height as needed and regenerate the STL for the upper bracket. The existing pieces are designed for a height of about 12 3/4 inches above the windowsill.

This Thing was designed entirely in OpenSCAD in my usual style of design, using pieces split down the middle with alignment holes and filament pegs so that all pieces can be printed without support. The split pieces do require the additional step of gluing together, but the result is much better than attempting to print complex pieces in a single print.

Also I have settled on a style of writing OpenSCAD scripts so that the source file contains one module for each piece, one module for each piece split and positioned for printing, and one module representing the entire assembly. The file comes with the assembly drawing uncommented. To prepare each piece for printing, comment out the assembly line, and uncomment each printed piece, render, and export to STL.