You need to place it somewhere stable. The reason is that the point where it sharpens needs to be in an open space so the chain can rotate. The machine is silent. Its stone is not very hard, I would say it is rather soft, but you can change it with any stone you want, they are cheap. You adjust the chain at the right spot so each tooth can be sharpened and simply lower the wheel. There is also a small wheel next to the main wheel that you need to tighten so as not to damage the joint of the teeth. I did everything correctly and sharpened two chains of mine that have to cut tons of logs. The job was done and now they cut like razors. Of course, after two or three sharpenings, I will need to lower the guide a bit, but for now, both saws work non-stop and effortlessly. I believe this machine is worth buying. I don't know about the differences it has compared to others on the market, but at this price, it is definitely a good purchase.