Just for info, Centronics interface is very slow for 3D printer. It could work (as 2D plotters work), but people make figures faster, and 3D made things even worse.
3-D printers are much lower bandwidth than conventional 2-D printers, and the conventional Centronics parallel port could handle up to "75,000 characters per second", according to https://en.wikipedia.org/wiki/Parallel_port#Centronics. The total amount of data in a print is larger, but typically the 3-D printer is only processing 1–10 commands per second, compared to about 100 for a dot-matrix printer.
But the point I was trying to make was that dot-matrix printers predated the availability of microcontrollers, or even microprocessors, and you needed cheap microprocessors to make hobbyist 3-D printers.
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.
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.
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).
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, as I mentioned in 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 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-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?
> 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.
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.
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
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.
I usually state: for use opportunity, you must run business.
Well, must admit, this is not only way, but most effective.
Also possible to use opportunity in educational environment or at community or in government organization. But from organizational science, all of these are just special type of business - educational business, or business owned by community , or business owned by government.
And yes, many people are practically running business, but don't think it is business. And this is very serious problem for economy, because they use this opinion "not a business" as consideration to avoid vital business transactions, and thus killing opportunities.
Yes, I agree, providing more info you become more vulnerable.
No, at concurrent market appear more priority matters.
You sure hear about Queueing theory, and may be you know, when execution unit wait for something, this time subtracted from max performance, and in worst case EU could wait 100% of time, so performance will be zero, no matter how fast EU could run ideal case.
How this apply to economy - business do many things without guarantees, only based on trust ("business is all about trust" - you could make big table with this phrase and hang it on the wall as icon).
In low tech business, typical to invest large resources to stored things, so people could just pay money and got product immediately, and do not wait until it will arrive from fields.
In high tech business appear additional dimensions, investments made into r&d and into prototypes of products, before mass production.
Services are just genuine trust, as in many cases you cannot know if service suitable for you before use it, so you should buy small amount of service or service business should spent some amount of it's resources to make gifts to try.
Any way, in many cases, need significant amount of borrowed money to start business or to scale business, and the more trust have subject, the cheaper will be borrow for him.
Statism is usually considered State as intermediary, who in theory should guarantee deals and even borrow cheap money, but this scheme is very limited and vulnerable for not good enough persons, because State itself must got resources somewhere to store them and to have something to share. If state have no spare resources it cannot guarantee anything. Not good persons use lot of tricks to force people to give their resources to State, and in extreme case just use violence to pick up resources from their owners (sure, this is bad for trust and killing free market).
Ideal business as I said before, called for trust. For example exists Islamic banking, which is extremely similar to idea of Venture Fund, and invented because for Muslims prohibited to give money for percents. So they create business with acceptor of money and got share in this business, and involve in this business to control that money will be spent wise.
And the last I should say - some people think, business could grow on internal money, just constantly withdraw some small amount from money circulation and reinvest these money into business grow.
Well, this scheme is working, but exists one problem - many business opportunities are limited in time, exists sort of time window (you could read more on this in ballistics or in space science, they use term as usually exists positions of planets, most energy effective). You could use such opportunity only if you will do things fast enough, so create your product or service before time window closed.
And grow on internal resources is very slow, usually it is just few percents faster then inflation, but to finish inside good time window in many cases need large investments, tens percents of turnaround or even more than turnaround, so without cheap borrowed money business will lost opportunity.
But to borrow money need to show clear enough organization; you may hear about Due Diligence, but I think you are not know, that Due Diligence is usually much more strict and deeper than tax reporting. So conclusion - to have more success in using business opportunities, you must share much more information than to just deal with state regulations.
Things looking even worse if we look on insurance and on finance transactions - typically insurance and finance transactions fees are depend on trust, so very high probability, semi-hidden business will constantly lose few percents of turnaround, and will be even more limited in using opportunities.
More detailed on this you could read in books from Acemoglu, Mises, Elinor Ostrom.
> a few 555s to drive your motors aren't going to make the difference between feasibility and infeasibility
It depends on current market of considered niche. For some cases, market price is so low, every additional hole or trace on PCB could kill economy; for others, could include something like SGI or Cray as controller (mean, something severe overpriced) and it will be still profitable.
