Sunday, August 14, 2016


Beat-up old Venetian blinds
My house came with old beat-up Venetian blinds on most of the windows.  They're not in great shape, they don't keep out the light (and heat) particularly well, and the raising/lowering mechanisms on a lot of them are broken.  The summer heat and intense sunlight has convinced me that I should replace them with something that keeps the sun out better.

My parents have vinyl pull shades that have lasted over 25 years.  This seems like a pretty good advertisement for vinyl pull shades, so I did a little looking. had exactly what I wanted for the right price, so I ordered 13 shades, one for each of my inward-swinging casement windows.

When I received my new shades, they didn't fit.  The fabric was too narrow by quite a bit.  What went wrong?

In the world of interaction design (a way of designing software user interfaces focused on how people interact with it), there is a distinction between a mistake and a slip.  A slip is when the user does something by accident like makes a typo or puts the wrong number in a box or clicks a button without intending to.  A mistake is when the user does something intentionally and purposefully that turns out to be incorrect because they at some point made an incorrect assumption about what they needed to do or how something worked.  For example, maybe they used the wrong formula to calculate a number in Excel because they misunderstood the mathematical operation of the formula.

When I ordered my blinds, I did not make any slips.  I read my tape measure correctly, entered all the numbers and other information correctly into the website, and clicked all the right buttons.  The factory fulfilled my order exactly as I specified, so they did not make any slips either.

Why didn't they fit?  It's because I made a mistake.  I measured my windows and determined that the shade should be 21 inches wide to cover the glass, so I requested shades of 21 inches.  However, as it turns out, the width measurement reflects the width of the entire assembly, including not only the fabric of the shade but also an inch an a half or so of mounting hardware on the sides.  So when you order a shade that is 21 inches wide, the fabric itself is less than 20 inches wide.  In retrospect, this makes total sense because this is the measurement that matters if you're mounting the blinds on the inside of a window frame.  But I didn't think of this because my windows swing inward, so I will be mounting the shade to the window itself and not the frame (so the shade will swing inward along with the window).  I was not really thinking about constraints on the location of the mounting hardware because I'll just screw it right into the window.

I looked at the website again, and I finally did find, in fine print, the information about how to measure correctly.  It would have been much more helpful if it included some diagrams and an explicit statement of how much of the total measurement was fabric vs. mounting stuff.  I suppose this is a design flaw on their part.  Good design prevents users from making mistakes.

But, has a special "SureFit" guarantee and offers to replace your custom blinds if they don't fit, even if the reason they don't fit is that you made a mistake in measuring your windows.  Their customer service was extremely helpful, and although I had to be bumped up the food chain to more senior-level people a few times because of the size of my order, they honored their guarantee and offered to replace all 13 shades with the correct size at no cost to me.

Oversized mounting bracket - Bang!
However, there was one other problem with the shades besides the width.  The mounting brackets were very large and clunky.  This means that the shade itself would hang quite far from the window glass, so a lot of light would leak around the sides of the shades.  Also, because the brackets stuck out so far from the window frame, when I opened the window wide, the bracket would bang into the window frame before the window was fully open.  This made me concerned over whether the concept of these roller shades would work at all, even if I did get them in the correct width.

I asked the helpful lady at if they had any smaller mounting brackets, but after checking with the factory, she said no, these were the standard ones the factory sends out, and there were no other choices.  I searched the internet a little bit for other options, but most websites either didn't give any dimensions for the mounting brackets, or the dimensions they gave were the size of the packaging they come in, which is totally useless for pretty much anybody (another mistake-generating website design flaw).  Finally, I went in person to Home Depot, and they had exactly what I was looking for, smaller outside-mount roller shade mounting brackets for 98 cents each.  That will do.

If I learned anything from this experience, it's that one should always order ONE of something as a test case before committing to a larger order.  This type of prototyping is a basic technique in interaction design and something I'm well familiar with in my professional life, so shame on me for not transferring those principles to the everyday world.  I feel bad about wasting's time and money and felt pretty dumb about the mistake in general.  So, after re-measuring my windows and researching the mounting hardware, I had send me one replacement shade in the correct size, as a test case.

The new shade was perfect, exactly what I wanted and exactly the right size.  The Home Depot mounting hardware worked just fine.  So, I ordered the other 12.  I told them they didn't need to send me their mounting hardware, but apparently the factory is incapable of not sending it along with the shades, so I got it anyway.  I put up all the new shades, and I donated the wrong-sized shades and the extra mounting hardware to Habitat for Humanity.

All in all, this was a frustrating experience that turned out fine in the end.  Note to self: Don't forget that most skills transfer from one aspect of life to another.  Skills used in software design are pretty useful for a lot of other things.
New roller shades

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