{"product":{"product_id":"0691149925","title":"How Round Is Your Circle?: Where Engineering and Mathematics Meet","price":"28.95","image_url":"https://m.media-amazon.com/images/I/41dzkhIawqL._SL500_.jpg","url":"https://www.amazon.com/dp/0691149925"},"comments":[{"body":"You might enjoy the book *How Round is Your Circle*, https://www.amazon.com/dp/0691149925","subreddit_name":"math","author":"jacobolus"},{"body":"Your link threw some sort of weird error, so heres the amazon link for the mobile peeeps https://www.amazon.co.uk/dp/0691149925/ref=cm_sw_r_cp_apa_blrDBb50XY1YS","subreddit_name":"gifs","author":"cantaloupelion"},{"body":"I recently read [this](https://www.amazon.com/How-Round-Your-Circle-Engineering/dp/0691149925) book about circle checking and more. It's quite good but if you're not into math/history/philosophy then I think OP is talking about [this](http://i.imgur.com/fIZKwei.gif).","subreddit_name":"OHSA","author":"RainbowNowOpen"},{"body":"The problem is you can't do it with a single tool. If we only used a ruler to make a new ruler, which then made a third ruler; each generation is successively worse. By combining a ruler, a level, gauge lengths, etc. you can make more accurate tools down through the generations, which is exactly how we've gotten to the point of creating parts accurate down to tenths of a micrometer. \r\n\r\nTheoretically you could 3D print all of the parts needed for a new 3D printer then use traditional manufacturing methods to clean them up - drill, smooth, level, etc. But if you do that you've given up nearly every advantage of 3D printing and made parts unnecessarily expensive. At that point it'd be far cheaper, faster, and easier to just cut the parts out of a hunk of ABS plastic and be done with it. \r\n\r\nIf you're interested in this, check out [How Round is Your Circle](http://www.amazon.com/How-Round-Your-Circle-Engineering/dp/0691149925/ref=sr_1_2) and [Foundations of Mechanical Accuracy](http://www.amazon.com/Foundations-mechanical-accuracy-Wayne-Moore/dp/B0006CAKT8/ref=sr_1_1) (long out of print but fairly easy to find in libraries). They do a good job of explaining the history of accuracy in mechanical parts. ","subreddit_name":"askscience","author":"ood_lambda"}]}