4 ms·

It is necessary to grind in a random fashion (OP is talking about the method of grinding, not the order), or you will end up with imperfections. Lots of info ab

It is necessary to grind in a random fashion (OP is talking about the method of grinding, not the order), or you will end up with imperfections. Lots of info about this if you look in to grinding mirrors for telescopes. Also, the order being random wouldn't effect the end result.

openandshut 5y ago
If it's a machine doing the grinding, what is the source of randomness?
- ruined 5y ago
  input
- dylan604 5y ago
  function setPostion(float x=random(), float y=random()){}
  - datameta 5y ago
    I imagine the PRNG they use for this is a rather thorough implementation. Unless perhaps it is even necessary to used a cryptographic chip to generate true randomness.
    - dylan604 5y ago
      pseudocode my man, pseudocode. ignite the imagination, and let the reader run wild. however, now my imagination is now running, and thinking about how overkill "true" random might be for this application. something "random" like an orbital sander would probably be enough. you're just trying to get away from side-to-side, left-circle, right-circle, up/down patterns. you're doing this to 3 different surfaces, so they would grind out any slight patterns which is the point. seems like a try crypto random would be as "effecient" as my roomba appears not to be.
      - datameta 5y ago
        I suppose I went a bit overboard (no pun intended). 1 KB implementation should be more than enough for their precision. Maybe some code then, instead: https://www.dwitter.net/d/20446 https://www.dwitter.net/d/20446
platz 5y ago
When grinding the concave plate why didn't that make then other flat plate convex again?
- wizzwizz4 5y ago
  It did – but less so than the original was concave. By rubbing them together, you're effectively “averaging out” the convex / concavenesses.
- jlokier 5y ago
  As the sibling comment explains, it does make the other flat plate convex, but by a smaller amount. Their shapes sort of average out. I'll add that this depends on the materials having similar properties, so when ground together, they are grinding each other. This means whatever residual shape you have in one of them, it won't be transferred completely to the other. If the materials had very different hardnesses, one of them would dominate over the other when they're ground together.

openandshut 5y ago

If it's a machine doing the grinding, what is the source of randomness?

ruined 5y ago
input
dylan604 5y ago
function setPostion(float x=random(), float y=random()){}
- datameta 5y ago
  I imagine the PRNG they use for this is a rather thorough implementation. Unless perhaps it is even necessary to used a cryptographic chip to generate true randomness.
  - dylan604 5y ago
    pseudocode my man, pseudocode. ignite the imagination, and let the reader run wild. however, now my imagination is now running, and thinking about how overkill "true" random might be for this application. something "random" like an orbital sander would probably be enough. you're just trying to get away from side-to-side, left-circle, right-circle, up/down patterns. you're doing this to 3 different surfaces, so they would grind out any slight patterns which is the point. seems like a try crypto random would be as "effecient" as my roomba appears not to be.
    - datameta 5y ago
      I suppose I went a bit overboard (no pun intended). 1 KB implementation should be more than enough for their precision. Maybe some code then, instead: https://www.dwitter.net/d/20446 https://www.dwitter.net/d/20446

platz 5y ago

When grinding the concave plate why didn't that make then other flat plate convex again?

wizzwizz4 5y ago
It did – but less so than the original was concave. By rubbing them together, you're effectively “averaging out” the convex / concavenesses.
jlokier 5y ago
As the sibling comment explains, it does make the other flat plate convex, but by a smaller amount. Their shapes sort of average out. I'll add that this depends on the materials having similar properties, so when ground together, they are grinding each other. This means whatever residual shape you have in one of them, it won't be transferred completely to the other. If the materials had very different hardnesses, one of them would dominate over the other when they're ground together.