Sounds like a great idea.  I have written a ton of tech articles, both for my web site and when FordMuscle was paying me to do it and I have two pieces of advice for you:

1.  Take more pictures than you think you will need.  In most cases you will do the project then write the article and if you don't already have the picture you want you simply won't have one.  Some times you don't even realize a picture would be good there until you start writing the article so take pix of everything.

2.  write in such a way that makes sense for someone with no experience.  When I was in collage one of my my english professors gave us each two pieces of paper and told us to wright the directions for making a paper airplane on one of the pieces of paper.  Then when we were done we passed our directions to our neighbor and they had to follow our directions exactly and not draw from our own experience.  No one in the class was able to use the directions to make a paper airplane.  The reason for that is as we were writing we were not specific enough and assumed knowledge on the part of the direction follower.  A good technical article will spell it out simply, concisely and not leave any room for interpretation.  Just my .02