One-man SMD Assembly Line Shares A Lot Of Tips About Doing It Right

Need to use that antiquated hardware that can only be connected via a parallel port? It might take you some time to find a computer that still has one of those, or you could try out this USB to Parallel port converter. It’s not limited to working with printers, as the driver builds a virtual parallel port that you should be able to use for any purpose. But what we’re really interested in here isn’t the converter itself, but the build process. [Henrik Haftmann] posted a three-part series of videos on the assembly process, which you can watch after the break.

The build is mostly surface mount soldering with just a handful of components that need to be hand soldered. The first of his videos shows him stenciling solder paste onto the boards. From what we can see it looks like he built a nice jig for this using scrap pieces of copper-clad which match the thickness of the PCB, and hold it and the stencil securely in place. There’s a bunch of other tips you can glean from the videos, like the image seen above. It’s a clamp that holds the PCB and USB jack together while they are soldered.

If you’re ever thinking of assembling a bunch of boards you should set aside thirty minutes to watch them all.




[Thanks Panikos]

33 thoughts on “One-man SMD Assembly Line Shares A Lot Of Tips About Doing It Right

  1. Unfortunately USB is a packet protocol, and the speed at which the packets move is not reliable. There is too much jitter to use this for many higher speed io tasks. A PCI parallel port for $15 will work if you have a desktop.

    1. But USB is deterministic. if you connect it directly to a host port so that you have all the bandwidth for your port converter I think you can be pretty sure that it’ll work with very low latency to change and predictably.

      1. If most people would follow half of those rules a lot of time would be saved for people who actually have to read email and reply to it.

        I once emailed 2 questions to a customer of mine which couldn’t be replied with a simple yes or no. His top posted reply was “OK, John, I agree, go ahead”… When confronted with this he told me that he top posted to save time… Sure, he saved a lot.

    1. He rejects mails with spelling mistakes, but I noticed a few grammatical errors on his email page:

      “these rules are to go without saying”

      “Do you have read this thoroughly?”

      “these rules are applicable for the vast of email users”

      I’d email him to tell him, but I’d be afraid that I’d violate one of his rules.

      1. He allows spelling and grammar errors. Just not too many.

        I have something like this set up as a responder for people who are too inept to understand basic email etiquette. More or less it states that if you want me to read your message, make it readable before resending it.

        As for the videos, I thought they were quite entertaining. Could’ve used a change in music, though.

    2. I think he’s absolutely right.
      If you’ve been around the internet for over 10 years, these rules are normal and quite self-explanatory. No one wants to read badly written e-mails without knowing what people are referring to; more often than not, spelling mistakes are a sign of laziness and experience shows that people aren’t only lazy when it comes to spelling, the actual content will suffer as well. So it’s absolutely understandable. I think it’s rather nice to actually write these rules, because I myself wouldn’t read e-mails which don’t pass his criteria if I got more than one e-mail a day.

      Also, he’s a nice guy, responds really quick and his answers to questions about his stuff are quite helpful.

      1. Absolutely right, couldn’t agree more! Even if it makes me look like a bastard, I can’t stand it when people can’t even be bothered to write things coherently, it’s a goddamned waste of my time to read it AND it pisses me off.

        On a less serious note…of course he responds quickly; only 2-3 emails a week make it through his ‘filter’. ;P

      1. There really is no reason to send people unrequested 1 MiB attachments.
        HTML e-mails suck big time. They don’t flow properly and if some clown sends you everything in 24-pt yellow Comic Sans, you have to put up with it. So why do you need html e-mails? Isn’t it all about the text, the actual content, and not about how you’d like to look it on another person’s computer?

        Many people do exactly the same as him, the only exception being he sais up front what requirements he’s having for e-mails, whereas other persons would just delete the e-mail unread.

      2. I’m sorry bandwidth concerns have not been resolved completely, at least affordable bandwidth concerns anyway. I have a 1.5 M wireless connection to the internet, that’s affordable now, but I could be busted back to slow rural dialup connection at any time because of finances. Even an internet connection via satellite, isn’t a technological possibility for some, even if they could afford it

    1. It is to help the components align with their footprints. Surface tension will generally pull the parts into their correct position but sometimes they might need a little nudge to “jump” into place.

  2. I am not sure my hands are quite that steady anymore. But may have to give it a go sometime anyway.

    As avrpunk said there are many potential issues using USB to Parallel. However, I am sure there are a lot of things it would work for quite well too. It all depends on the application requirements.

  3. Kudos for this guy’s ingenuity (I particularly liked the through-hole to SMD part conversion process). He must either really love this kinda of stuff or have *tons* of time to spare. The friendly folks in Shenzhen would happily do the assembly for quite less than a buck per board (I’m assuming he wants to make at least a hundred of these).

    Unless the USB controller on the board does some pretty magical processing and buffering to de-jitter the USB 2.0 stream, this doesn’t sound very promising for all but very simple use-cases. Don’t try to use this if you need a parallel port to control something like a CNC machine. Maybe an old, slow printer?

    A PCI card or a PCMCIA parallel for (for a laptop) are a much better and more reliable solution. I’m not sure about PCI-E cards.

    1. I think what you’re seeing there is the mindset behind the “legendary German quality,” which has been long lost in industrial production.
      One defining moment of this is populating the LEDs–he built a jig to position them at exactly the same height so they’ll barely fit through the case’s holes. That’s just beautiful, but of course, it’s a total waste of time. You could also just place them on the PCB, solder, you’re done. At first I was mildly confused at his weird choice of connectors–there are through-hole DB25 and SMD Mini-USB connectors, so why the weird connectors and lots of time taken to prepare them? But then the answer hit me: Like this, everything will be in the middle of the case and it’s stable as hell, so these connectors can take a great deal of stress without breaking off or otherwise losing contact.
      It’s hard to understand he doesn’t use cheap and quick methods of production, but I think that would sacrifice “quality,” even if the level of quality so attained would probably still suffice.
      Also, as you can clearly see, it’s just a hobby. He sells these for a ridiculously small markup, even moreso if you look at the effort and time he spends assembling these things.

  4. If you’re gonna watch these vids, turn your sound down. the song gets annoying after the 3rd time through it.

    Other than that I thought it was an excellent walkthrough..

  5. I can think of a few things I would do to improve the work flow. (when you are self-assembling products, each step is money and time lost)

    Toaster oven to reflow a dozen boards at once.

    I’d suggest a thinner PCB so you don’t have to bod the DB connector.

    And, There’s got to be a better way of soldering the USB connector then the time consuming jig he’s using. That made me cringe a little.

    And the email thing. Yea.

  6. If you watched all 3 videos completely you should know that you might actually be dead :O, it’s the only explanation for your patience.


    This does make all handmade products suddenly seem cheap though.

    1. I must concur. The assembly process is way too elaborate. He must spend at least forty minutes making each component(including programming and testing). He can’t be making that much money.

      And yes this is of course for use with printers. As far as anyone thinking of using this for real time control from their quad core computer, they are idiots; it’s like trying to drive nails with a jackhammer. Microcontrollers are the DOS PC of old. Program the dedicated microcontroller to do all the real time stuff and communicate with a PC through asynchronous USB commands. Those old machines didn’t have microcontrollers but if they were made today they would.

      So what would really be cool and worthy is if he were were making a system on a chip reprogrammable interface computer. Something like a 128KB 25mhz computer. Just enough for program and buffer space.

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