Is the Printrbot forum not terribly helpful?
My Printrbot would detect the bed in the first spot.
Move to the second spot and go up, up.
Move to the third spot and go up, up.
If your bot acts kind of like this it means that something is wrong with your probe or your firmware or something. Use M119 to see if you can get z_min to be triggered at different positions. In my case it was easy to see that it would trigger near home, but not away so I could tell the probe was broken. Because the only difference was how the wires were stretched I had a strong suspicion it was somewhere in the middle of that wire pull that was getting moved.
None of the other wires in the bundle were having any problems so I don't know why the probe wires are so cheap. Anyway, I did it the proper DIY way chopped out the bulk of the wire and soldered in some heavier duty electrical wires I had laying around.
It looked like this.
I keep the thinner wires on the probe and the connector and soldered there because it was easier that tearing those apart and reconnecting. I fished the probe back into place and it works flawlessly.
I've had 2 different probes fail due to garbage thin wires, but never had a problem with the firmware as some people claim is part of the problem.
So if your probe stopped detecting the your metal build surface you may as well try replacing the wires. It's the maker way after all.
