[de_]

If you only install 1 board a year and a mentor does it as opposed to a random student, then sure you are less likely to have a problem.

But in our team, random students installed at least 5 boards on various desktop and test & competition robots this year alone (many when I am not there).

What is the probability a student will realize the stub is brass and its tensile strength is 19K PSI versus the grade 8 fasteners we use which is 150K psi. Zero. We don't teach metallurgy in our high school. We don't own a torque wrench. What student could possibly recognize the metric nuts Zero - looks just like a 1/4 nut. Standard 1/4" 20 nut fits on the stud and tries quite happily to cut a thread into the soft brass. That is how a student trashed our first PDE.

This is a $190 hidden mine waiting to explode, especially in a dynamic high student to mentor ratio environment. Count your self lucky if you have not had it happen yet.

The particular student in this case has install a lot of PDEs over the years. He's installed a lot of brass pneumatic fittings in aluminum with no issues. He has no history of brute force. He used a small wrench. So don't blame the student.

Our robot is probably 50% over budget this year and now we should be buying a new PDE and a new Digital side cars as both did not survive even a minute in our student environment. Is it the students fault or is it a design fault? I can't find fault with the students.

What I will do between trying to get a robot built and buying replacement parts is try to find the time to make a warning label for future PDEs that warns the studs are brass and metric and will break 7.5 times easier than a grade 8 bolt. Something FIRST might consider. I will also send a link of this post to FIRST.