3 ms·

The article has nothing to do with 3d printing.

by jstanley 3y ago

deleted 3y ago
[deleted]
hinkley 3y ago
Do you think there's a fundamental difference between how CNC, 3d printing, and laser cutting equipment behaves?
- c22 3y ago
  Yes, several.
  - hinkley 3y ago
    Okay, well, that was informative. And explains why my point doesn't hold because I said a wrong word that has little to do with the point. Thanks for your efforts.
    - c22 3y ago
      I don't know what you were trying to imply and I have no dog in this fight. But there are definitely fundamental differences between additive vs subtractive technologies, 2-axis vs 3-axis or multi-axis machining, and more niche machine-controlled manufacturing technologies, as well as very real differences behind the driving algorithms of most 3d printers/CNC machines vs most commercial laser cutters. (3d printers and other CNC tools have a pedigree stretching back to the original g-code developed in the 50s whereas laser cutters/engravers descend from more modern laser and inkjet printing technologies developed in the late 70s and 80s.)
      - madengr 3y ago
        [dead]
- jstanley 3y ago
  CNC and 3d printing typically use G-code, which has dedicated arc commands (G2, G3), and the laser cutter in the article uses PDF, which (apparently) does not, and is the main point of the article. Of course any physical machine is only making an approximation of a circle (even a lathe doesn't turn perfectly round, there is no such thing), but at least for CNC and 3d printing you can specify a perfect circle. In PDF you can't. (Yes, it is also true that a typical 3d print comes from an STL file, which can only specify triangles, so STL files also can only specify approximations of circles. But it is still true that most 3d printers run G-code, not PDF.)
  - defrost 3y ago
    The PDF format was intended to be an explicit per page device independant description of text, line path, and image layout subject to clipping with no "program running" elements to it. It followed PostScript which was a programming language that was intended to be directly undertood and runnable by Postscript enabled printers. Postscript could easily do the job here, it had "arc" drawing primitives that described circles (both full and partial). The 'failure' of Postscript was that as a programming languge a bad .ps job could crash a printer and a 1,500 page .ps document had to be internally fully rendered just to print out page 73 only (potentially code on any 'page' could loop back or forward and generate image elements on any page). As a not-quite PostScript simplified 'other' the PDF formal languaage spec only allows the drawing of lines and 'curves' and curves are explicitly 3rd order bezier splines. See: Path Operators (Page 95) Portable Document Format Reference Manual (230 pages) https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/pdfreference1.0.pdf https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandard...
    - hinkley 3y ago
      SVG would likely be a better target today.
  - hinkley 3y ago
    > even a lathe doesn't turn perfectly round, there is no such thing You don’t have to look for long on YouTube to find videos showing lathe tolerances of ten mil or lower. And things like bearing races, where imperfections are a common failure mode, are turned for polishing if nothing else.

The article has nothing to do with 3d printing.

deleted 3y ago

[deleted]

hinkley 3y ago

Do you think there's a fundamental difference between how CNC, 3d printing, and laser cutting equipment behaves?

c22 3y ago
Yes, several.
- hinkley 3y ago
  Okay, well, that was informative. And explains why my point doesn't hold because I said a wrong word that has little to do with the point. Thanks for your efforts.
  - c22 3y ago
    I don't know what you were trying to imply and I have no dog in this fight. But there are definitely fundamental differences between additive vs subtractive technologies, 2-axis vs 3-axis or multi-axis machining, and more niche machine-controlled manufacturing technologies, as well as very real differences behind the driving algorithms of most 3d printers/CNC machines vs most commercial laser cutters. (3d printers and other CNC tools have a pedigree stretching back to the original g-code developed in the 50s whereas laser cutters/engravers descend from more modern laser and inkjet printing technologies developed in the late 70s and 80s.)
    - madengr 3y ago
      [dead]
jstanley 3y ago
CNC and 3d printing typically use G-code, which has dedicated arc commands (G2, G3), and the laser cutter in the article uses PDF, which (apparently) does not, and is the main point of the article. Of course any physical machine is only making an approximation of a circle (even a lathe doesn't turn perfectly round, there is no such thing), but at least for CNC and 3d printing you can specify a perfect circle. In PDF you can't. (Yes, it is also true that a typical 3d print comes from an STL file, which can only specify triangles, so STL files also can only specify approximations of circles. But it is still true that most 3d printers run G-code, not PDF.)
- defrost 3y ago
  The PDF format was intended to be an explicit per page device independant description of text, line path, and image layout subject to clipping with no "program running" elements to it. It followed PostScript which was a programming language that was intended to be directly undertood and runnable by Postscript enabled printers. Postscript could easily do the job here, it had "arc" drawing primitives that described circles (both full and partial). The 'failure' of Postscript was that as a programming languge a bad .ps job could crash a printer and a 1,500 page .ps document had to be internally fully rendered just to print out page 73 only (potentially code on any 'page' could loop back or forward and generate image elements on any page). As a not-quite PostScript simplified 'other' the PDF formal languaage spec only allows the drawing of lines and 'curves' and curves are explicitly 3rd order bezier splines. See: Path Operators (Page 95) Portable Document Format Reference Manual (230 pages) https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandards/pdfreference1.0.pdf https://opensource.adobe.com/dc-acrobat-sdk-docs/pdfstandard...
  - hinkley 3y ago
    SVG would likely be a better target today.
- hinkley 3y ago
  > even a lathe doesn't turn perfectly round, there is no such thing You don’t have to look for long on YouTube to find videos showing lathe tolerances of ten mil or lower. And things like bearing races, where imperfections are a common failure mode, are turned for polishing if nothing else.