I've read a lot of people use soldering irons to make their holes in plastic tubs. What I'm wondering is how do you keep them from breaking(stop heating) after the first use? I've bought 3 different ones that worked great the first time using them, but when I went to use them a second time they would not heat up at all. I will say the first two were on the cheaper side, but the last one wasn't and it still stopped heating on me. It's getting really annoying to say the least. Is there some little trick I'm not doing? Or did I just purchase three different bad soldering irons?

Any advice would be good! Thanks!