5 ms·
Video of a very inefficient concrete drill (read description)
- tjic 18y agoSo, everyone gets that each stage in the reduction reduces the number of rotations per second, and therefore the stage that's embedded in concrete is moving very very slowly. ...but still, concrete being very brittle in tension, shouldn't it crack? The answer is no, because of something called "backlash". In short, there's a little bit of play in each of the gears, and one can "take up the play" in each stage before force is transmitted through the stage. There's two kinds of play: actual air gap, and also elasticity of the steel gear teeth. Dealing with backlash is a key component in designing machine tools like metal lathes and milling machines. High end CNC tools use ball screws and other techniques to reduce the amount of backlash experienced.
- regularfry 18y agoGiven that everything's running in one direction, couldn't you manually take up the play in each section during construction, working back from the concrete block, so that the whole thing's at tension when you connect the motor? I appreciate that wouldn't affect the elasticity much, but the air gap would be taken care of at least...