Parametric Ruler Stop

This is a simple parametric ruler stop. I'm including the FreeCAD file and a number of stops for which I've already saved for the rulers I have.

All you have to do is to modify any parameter within the spreadsheet with a cyan background color (snapshot included). The "Slider Gap" covers "shrinkage". That is, if your plastic shrinks during print and you need a little extra gap, this is what that parameter is for. "Wall Thickness" is just how sturdy you want it to be, but also plays a role in the bolt because some material is needed for the bolt to hold the ruler still. The spreadsheet also comes with the measurements of the rulers I have on hand. I've taken a picture of a few I keep at my desk.

All STLs are designed to be printed with the M12 bolt included with the FreeCAD design. Like all plastic prints, you'll need to take a little time to force the tap after printing by slowly screwing in the bolt, backing it out, then more, then backing it out, etc. Once tapped, it is smooth as glass. I found the M12 to be a great size for all rulers I have. If you have something really small, then you might need to change that.

When you print the stop, arrange it so the void in the stop part is vertical, rather than flat. This, then, requires no supports. If you print the bolt head down, you can avoid problems as well. You certainly don't want supports in the bolt nor the tap hole in the stop part (Refer to the photo for orientation).

I did print at standard quality (based upon the Cura settings). At low quality, I kept breaking the bolt during tapping, but that could just be due to my print material.