When you’re just learning to sketch, you use graphite. Why? It’s cheap, great at training you to recognize different shades, and most of all, it’s erasable. When you’re learning, you’re going to make mistakes, and un-making them is an important part of the game. Same goes for electronics, of course, so when you’re teaching someone to solder, don’t neglect teaching them to desolder.
We could argue all day about the best ways of pressing the molten-metal undo button, but the truth is that it’s horses for courses. I’ve had really good luck with solder braid and maybe a little heat gun to pull up reluctant SOIC surface-mount chips, but nothing beats a solder sucker for clearing out a few through-holes. (I haven’t tried the questionable, but time-tested practice of blasting the joint with compressed air.)
For bulk part removal, all you really have to do is heat the board up, and there’s plenty of ways to do that, ranging from fancy to foolish. Low-temperature alloys help out in really tough cases. And for removing rows of pinheaders, it can help to add more solder along the row until it’s one molten blob, and then tap the PCB and watch the part — and hot liquid metal! — just drop out.
But the bigger point is that an important step in learning a new technique is learning to undo your mistakes. It makes it all a lot less intimidating when you know that you can just pull out the solder braid and call “do-over”. And don’t forget the flux.
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[shadeydave] wanted to build his own Lawnbot, but he had no idea where to start. He purchased some DIY plans online which looked like they would get the job done, but then he strayed from the path in a big way and spent gobs of money in the process.
In his Instructable writeup, he details each misstep he made, explaining why his choices were bad as well as how much each mistake cost him. It sounds like pretty much everything that could go wrong did go wrong, from spending money on unnecessary microcontrollers to choosing the wrong wheels. Our favorite part is where he mentions that he couldn’t figure out how to create a “kill switch” for the Lawnbot in the event that his transmitter loses contact with the speedy whirling death machine.
[shadeydave] is well aware of how poorly his build went, and primarily wrote it up as a cautionary tale to others out there who might decide to take on a similar project. He says that the Lawnbot works for the most part, but with his newfound wisdom he will be revising the bot, having learned from his mistakes.
We actually like to see this kind of writeup as they can be quite beneficial to someone trying to put together a similar project. So if you have some major flubs under your belt, don’t be shy about digging them out and letting us know. As Thomas Edison said, “I have not failed. I have just found 10,000 ways that won’t work.”
Continue reading to see a quick video tour of [shadeydave’s] mostly working Lawnbot.