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I built a computer vision device that used the top-down area of a penny as a calibration standard. Coins are useful, easy-to-get items that have relatively tigh
by rchowe 2y ago
I built a computer vision device that used the top-down area of a penny as a calibration standard. Coins are useful, easy-to-get items that have relatively tight manufacturing tolerances.
- cassepipe 2y agoWhat about wear ? Were they only new coins ?
- Retric 2y agoI’ve never seen significant ware on a coin in circulation. Have you?
- seqizz 2y agoI've seen enough wear to prevent them to be calibration material at least.
- deleted 2y ago[deleted]
- MadnessASAP 2y agoDepends on what your tolerances are. If you only need to be within a mm a coin is going to beat that by an order of magnitude. We use a pack of cigarettes as a gauge for one of the jobs we do. Quick, (not so) cheap, and readily available. May have to standardize on a vape though in the near future.
- swores 2y agoI have often, though I suspect not enough to make a significant difference to someone who is already OK with the slight variance between un-worn coins.
- xboxnolifes 2y agoI have coins that originally had milled edges that are now completely smooth.
- fanf2 2y agoOnly on counterfeit £1 coins, before the coins were redesigned to make them harder to fake
- wongarsu 2y agoEver since coin clipping got out of hand in the 1700s most coins feature milled edges or edge inscriptions. They make the edges more resistant to wear and make any wear easy to spot. Of course there's a limit to the precision you can get from coins, but considering the scale of their production and the account of handling they see they are surprisingly good
- rrr_oh_man 2y ago> in the 1700s It's been happening since ever.
- rchowe 2y agoOur area measurement application did not require that tight a tolerance (we were estimating yield on broken material). If I needed that tight a tolerance, I could have gotten proof coins from the mint, or potentially switched to using a real calibration standard like a gauge block.
- qup 2y agoAlso a penny is .750 exactly. None of the other US coins have a "useful" diameter.
- dotancohen 2y agoThe US nickel is so close to 5 grams that I've seen them used as weights in a laboratory.