4 ms·

3D FDM printers need much higher bandwidth, because their controller need to make PWM for motors control, and for other things. Yes, one could make 3D printer

by simne 2y ago

3D FDM printers need much higher bandwidth, because their controller need to make PWM for motors control, and for other things. Yes, one could make 3D printer without PWM, but it will be extremely slow, or even cannot do some things. With modern microcontrollers this problem resolved by using interface just for high level commands (all low level control performed by microcontroller), but on early machines used computer as controller and they have to deal with this. I have some experience with modern FDM and SLA, and I seen many cases, when FDM was severe limited with microcontroller PWM range.

kragen 2y ago
Right, you need a microcontroller in the printer to avoid having to send PWM signals over your parallel port. But they don't have to be modern microcontrollers. An 8051 or Z80 would be fine, maybe with some external chips for PWM generation.
- simne 2y ago
  > An 8051 or Z80 would be fine May be. Problem is by definition of G-code, which is much more than 8bit (as I remember, there somewhere between 12bit and 18bit if consider just integer numbers, but for example diagonal lines and arcs are calculated with floats). Yes, I know, digital 8bit CPU could calculate 32bit floats or even 64bit floats, but it is slow and need additional RAM. All these calculations are much easier to do on 32bit computer. > some external chips for PWM Additional chips are bad for economy by definition - because size of PCB grow and because additional pins mean additional costs also. That is why first designs was dumb, without any controller at all and driven by computer - to avoid additional chips. In modern designs microcontrollers used for convenience - so now printer could run without working computer (for example from file on flash).
  - kragen 2y ago
    I agree that 32-bit chips (and decent instruction sets) make everything much easier. You wouldn't necessarily have to interpret G-code on the 8-bit microcontroller itself, although it's about the same difficulty as interpreting BASIC on it. Keep in mind that keeping the motors of a 3-D printer busy only requires a few speed changes per second, maybe 10 at most. By contrast, the 8051 in an Epson MX-80 printed about 80 characters per second and had to actuate the 9 hammers in the print head with a new set of voltages 9 times per character, for a total of about 700 deadlines per second. When Don Lancaster was trying to figure out how to build 3-D printers and other "flutterwumpers" in the 01990s, his idea was to use a bigger computer to rasterize curves into a set of one-byte step commands that would be interpreted by an 8-bit microcontroller, for example in https://www.tinaja.com/glib/muse140.pdf https://www.tinaja.com/glib/muse140.pdf, as I mentioned in https://news.ycombinator.com/item?id=42080682 https://news.ycombinator.com/item?id=42080682. His first explanation of this concept may have been his July 01993 "Hardware Hacker" column in Electronics Now (previously in Radio Electronics and Modern Electronics) https://www.tinaja.com/glib/hack66.pdf https://www.tinaja.com/glib/hack66.pdf where he's exploring the possibilities opened up by Parallax's BASIC Stamp: > One potential use for the BASIC Stamp is shown in figure four. I’ve been doing a lot of work with the stupendously great PostScript general purpose computer language. In fact, this is the only language I use for all of my electronic design, pc layouts, stock market analysis, schematics, Book-on-demand publishing, and just about everything else. > All the camera ready figures you have seen here in Hardware Hacker for years have been done by using nothing but my word processor and PostScript. Device independently. > The only little problem has been that PostScript I/O tends to end up a tad on the skimpy side. Usually you only have three choices: Dirtying up otherwise clean sheets of paper or plastic; writing files to the hard disk; or returning your data back to a host for recording or other reuse. > The BASIC Stamp can instantly let you extend the genuine Adobe Level II PostScript to any personal project or machine of your choosing! > Assume you’ve got a homebrew machine that has an x-axis and y-axis stepper, an up/down mechanism, and a "both steppers home" sensor. This can be a vinyl signcutter, engraving, or embroidery setup. Or an automated printed circuit drill, a wooden sign router, or a Santa Claus machine. ["Santa Claus machine" was Theodore Taylor's 01978 term for a 3-D printer; it's what Lancaster consistently called them in his columns over the years.] > You could use two of your BASIC Stamp lines for RS423 serial comm with your PostScript printer. Use two lines for both x-axis stepper phases. And two lines for those y-axis stepper phases. One line for pen or drill or whatever up/down. And a final line that zeros only when both steppers are in their home position. > The hidden beauty here is that all of those fancier PostScript fonts and the level 2 tools immediately become available for use on your own custom homebrew rig. At unbelievably low cost. With zero royalties! Normally when people do diagonal lines and arcs on computers without FPUs, they don't use floats; they often don't even use integer multiplies per step, but rather strength-reduced algorithms like Bresenham's algorithm and the DDA algorithm Bowyer talks a bit about in https://3dprintingindustry.com/news/interview-dr-adrian-bowyer-10th-anniversary-reprap-133841/ https://3dprintingindustry.com/news/interview-dr-adrian-bowy.... I agree with you that additional chips are expensive, but in the overall scheme of things, a few 555s to drive your motors aren't going to make the difference between feasibility and infeasibility. So I think it's clear that we could have done hobby 3-D printers 40 years ago. What similar opportunities are we missing today?
    - simne 2y ago
      > What similar opportunities are we missing today? Something You have not done yourself or something for what You have not paid to someone else to do. Life is complicated, it is very typical when appear opportunity but nobody use it. Because to use opportunity need 3 things: 1. The will. 2. Enough qualification (or enough IQ and time to learn). 3. Free (!!!) resources or cheap borrowed funds. If only one thing from list is missing, it become extremely hard to use opportunity. For example, I live in Ukraine, and even without war, regulations in country are so prohibitive, that many services are not enter country or enter with severe limitations, like Paypal only enter with private accounts, but business accounts are not available in Ukraine. Yes, You understand right, idea cost nothing, but ability to implement ideas worth billions if find fertile environment. And yes, I spent lot of time to find ideas and I could share with You high level information on how to find (or generate) ideas. Just let me know if this theme is interest for You.
      - kragen 2y ago
        Yes, of great interest! And in particular I'm interested in how to make do in environments full of prohibitive regulations that make it difficult to do anything, because I live in Argentina.
        simne 2y ago
        What I learn in Usenet and on early forums, to avoid discuss country regulations, so I will not promise to support this branch of discussion. But well, as you ask, for about prohibitive regulations, we in Ukraine made (and making) two things. First, we are practically motherland of anarchy, and was few multiple years periods, when country live without government and without regulations. You could read about deregulation in books of https://en.wikipedia.org/wiki/Daron_Acemoglu https://en.wikipedia.org/wiki/Daron_Acemoglu and https://en.wikipedia.org/wiki/Ludwig_von_Mises https://en.wikipedia.org/wiki/Ludwig_von_Mises https://en.wikipedia.org/wiki/Murray_Rothbard https://en.wikipedia.org/wiki/Murray_Rothbard also I myself like Ostrom, Elinor (1990). Governing the Commons: The Evolution of Institutions for Collective Action. Second, when government become powerful, we read prohibitive as it is - we just avoid made business in prohibitive niches. Because of this appear paradox, government and armed forces said that country need rockets, they even allocated large budgets to buy rockets from private companies, but nobody make rockets as they are prohibited. In some cases, possible to make virtual business or semi-abroad - it is possible to create business in US or in EU (or other countries with adequate regulations) and hire people remote. As conclusion, I mean, the best way to deal with prohibitive regulations is just flee abroad, to country with more adequate regulations, and you could from abroad support deregulation struggle if you wish. But if it is hard to flee, you could try to open business abroad. For other opportunities I writing email.

by simne 2y ago

kragen 2y ago

Right, you need a microcontroller in the printer to avoid having to send PWM signals over your parallel port. But they don't have to be modern microcontrollers. An 8051 or Z80 would be fine, maybe with some external chips for PWM generation.

simne 2y ago
> An 8051 or Z80 would be fine May be. Problem is by definition of G-code, which is much more than 8bit (as I remember, there somewhere between 12bit and 18bit if consider just integer numbers, but for example diagonal lines and arcs are calculated with floats). Yes, I know, digital 8bit CPU could calculate 32bit floats or even 64bit floats, but it is slow and need additional RAM. All these calculations are much easier to do on 32bit computer. > some external chips for PWM Additional chips are bad for economy by definition - because size of PCB grow and because additional pins mean additional costs also. That is why first designs was dumb, without any controller at all and driven by computer - to avoid additional chips. In modern designs microcontrollers used for convenience - so now printer could run without working computer (for example from file on flash).
- kragen 2y ago
  I agree that 32-bit chips (and decent instruction sets) make everything much easier. You wouldn't necessarily have to interpret G-code on the 8-bit microcontroller itself, although it's about the same difficulty as interpreting BASIC on it. Keep in mind that keeping the motors of a 3-D printer busy only requires a few speed changes per second, maybe 10 at most. By contrast, the 8051 in an Epson MX-80 printed about 80 characters per second and had to actuate the 9 hammers in the print head with a new set of voltages 9 times per character, for a total of about 700 deadlines per second. When Don Lancaster was trying to figure out how to build 3-D printers and other "flutterwumpers" in the 01990s, his idea was to use a bigger computer to rasterize curves into a set of one-byte step commands that would be interpreted by an 8-bit microcontroller, for example in https://www.tinaja.com/glib/muse140.pdf https://www.tinaja.com/glib/muse140.pdf, as I mentioned in https://news.ycombinator.com/item?id=42080682 https://news.ycombinator.com/item?id=42080682. His first explanation of this concept may have been his July 01993 "Hardware Hacker" column in Electronics Now (previously in Radio Electronics and Modern Electronics) https://www.tinaja.com/glib/hack66.pdf https://www.tinaja.com/glib/hack66.pdf where he's exploring the possibilities opened up by Parallax's BASIC Stamp: > One potential use for the BASIC Stamp is shown in figure four. I’ve been doing a lot of work with the stupendously great PostScript general purpose computer language. In fact, this is the only language I use for all of my electronic design, pc layouts, stock market analysis, schematics, Book-on-demand publishing, and just about everything else. > All the camera ready figures you have seen here in Hardware Hacker for years have been done by using nothing but my word processor and PostScript. Device independently. > The only little problem has been that PostScript I/O tends to end up a tad on the skimpy side. Usually you only have three choices: Dirtying up otherwise clean sheets of paper or plastic; writing files to the hard disk; or returning your data back to a host for recording or other reuse. > The BASIC Stamp can instantly let you extend the genuine Adobe Level II PostScript to any personal project or machine of your choosing! > Assume you’ve got a homebrew machine that has an x-axis and y-axis stepper, an up/down mechanism, and a "both steppers home" sensor. This can be a vinyl signcutter, engraving, or embroidery setup. Or an automated printed circuit drill, a wooden sign router, or a Santa Claus machine. ["Santa Claus machine" was Theodore Taylor's 01978 term for a 3-D printer; it's what Lancaster consistently called them in his columns over the years.] > You could use two of your BASIC Stamp lines for RS423 serial comm with your PostScript printer. Use two lines for both x-axis stepper phases. And two lines for those y-axis stepper phases. One line for pen or drill or whatever up/down. And a final line that zeros only when both steppers are in their home position. > The hidden beauty here is that all of those fancier PostScript fonts and the level 2 tools immediately become available for use on your own custom homebrew rig. At unbelievably low cost. With zero royalties! Normally when people do diagonal lines and arcs on computers without FPUs, they don't use floats; they often don't even use integer multiplies per step, but rather strength-reduced algorithms like Bresenham's algorithm and the DDA algorithm Bowyer talks a bit about in https://3dprintingindustry.com/news/interview-dr-adrian-bowyer-10th-anniversary-reprap-133841/ https://3dprintingindustry.com/news/interview-dr-adrian-bowy.... I agree with you that additional chips are expensive, but in the overall scheme of things, a few 555s to drive your motors aren't going to make the difference between feasibility and infeasibility. So I think it's clear that we could have done hobby 3-D printers 40 years ago. What similar opportunities are we missing today?
  - simne 2y ago
    > What similar opportunities are we missing today? Something You have not done yourself or something for what You have not paid to someone else to do. Life is complicated, it is very typical when appear opportunity but nobody use it. Because to use opportunity need 3 things: 1. The will. 2. Enough qualification (or enough IQ and time to learn). 3. Free (!!!) resources or cheap borrowed funds. If only one thing from list is missing, it become extremely hard to use opportunity. For example, I live in Ukraine, and even without war, regulations in country are so prohibitive, that many services are not enter country or enter with severe limitations, like Paypal only enter with private accounts, but business accounts are not available in Ukraine. Yes, You understand right, idea cost nothing, but ability to implement ideas worth billions if find fertile environment. And yes, I spent lot of time to find ideas and I could share with You high level information on how to find (or generate) ideas. Just let me know if this theme is interest for You.
    - kragen 2y ago
      Yes, of great interest! And in particular I'm interested in how to make do in environments full of prohibitive regulations that make it difficult to do anything, because I live in Argentina.
      - simne 2y ago
        What I learn in Usenet and on early forums, to avoid discuss country regulations, so I will not promise to support this branch of discussion. But well, as you ask, for about prohibitive regulations, we in Ukraine made (and making) two things. First, we are practically motherland of anarchy, and was few multiple years periods, when country live without government and without regulations. You could read about deregulation in books of https://en.wikipedia.org/wiki/Daron_Acemoglu https://en.wikipedia.org/wiki/Daron_Acemoglu and https://en.wikipedia.org/wiki/Ludwig_von_Mises https://en.wikipedia.org/wiki/Ludwig_von_Mises https://en.wikipedia.org/wiki/Murray_Rothbard https://en.wikipedia.org/wiki/Murray_Rothbard also I myself like Ostrom, Elinor (1990). Governing the Commons: The Evolution of Institutions for Collective Action. Second, when government become powerful, we read prohibitive as it is - we just avoid made business in prohibitive niches. Because of this appear paradox, government and armed forces said that country need rockets, they even allocated large budgets to buy rockets from private companies, but nobody make rockets as they are prohibited. In some cases, possible to make virtual business or semi-abroad - it is possible to create business in US or in EU (or other countries with adequate regulations) and hire people remote. As conclusion, I mean, the best way to deal with prohibitive regulations is just flee abroad, to country with more adequate regulations, and you could from abroad support deregulation struggle if you wish. But if it is hard to flee, you could try to open business abroad. For other opportunities I writing email.