Blinkenlights For Your Parallel Port

May 13, 2020 by Tom Nardi 24 Comments

Most modern equipment is connected over USB, and generally speaking we’re all the better for it. But that’s not to say there aren’t some advantages to using serial and parallel ports. For example, the slower and less complex protocols can be a bit easier to debug when devices aren’t communicating, which [Jeremy Cook] demonstrates in his latest project.

Looking to troubleshoot some communications problems he was having between his computer and CNC router, [Jeremy] came up with a handy little gadget that will allow him to visualize data passing through each pin of the parallel port in real-time. Even from across the room he can tell at a glance if communication is active, and with a keen eye, determine if he’s getting bi-directional traffic or not.

From a technical standpoint, this is a pretty simple project. The custom PCB is essentially just a pass-through, with an array of 3 mm LEDs and matching 10K resistors hanging off the data lines. But [Jeremy] found it to be an excellent excuse to brush up his KiCad skills. As he explains in the video after the break, this project certainly won’t impress the folks that do PCB design on a daily basis; but if you’re still learning the ropes, these are precisely the kind of projects you should be looking for.

Before any of you say it in the comments, we already know devices like this are available commercially for a few bucks. But that’s hardly the point. Things would be awfully slow around these parts if we disregarded any project that had a commercial alternative.

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Open Source Pick And Place Has A $450 BOM Cost

May 11, 2020 by Mike Szczys 49 Comments

Give your grizzled and cramped hands a break from stuffing boards with surface mount components. This is the job of pick and place machine, and over the years these tools of the trade for Printed Circuit Board Assembly (PCBA) have gotten closer to reality for the home shop; with some models diving below the $10,000 mark. But if you’re not doing it professionally, those are still unobtanium.

The cost of this one, on the other hand, could be explained away as a project in itself. You’re not buying a $450 shop tool, you’re purchasing materials to chase the fever dream of building an open source pick and place machine. There are two major parts here, an X/Y/Z machine tool that can also rotate the vacuum-based parts picker, and the feeders that reel out components to be placed. All of this is working, but there’s still a long road to travel before it becomes a set and forget machine.

The rubber hits the road in two ways with pick and place machines: the feeders, and the optical placement. The feeders are where [Stephen Hawes] has done a ton of work, all shown in his video series that began back in January. The stackup of PCBs and 3D-prints hangs on the front rail of the gantry assembly, is adjustable for tape widths, and uses an interesting PCB encoder wheel and worm-gear for fine-tuning the feed. [Stephen’s] main controller board, a RAMPS shield for and Arduino Mega that runs a customized version of Marlin, can work with up to 32 of these feeders.

So far it doesn’t look like he’s tackled a vision system, although the Bill of Materials does include “Downwards Camera”, confirming this is a planned feature. Vision is crucial in commercial offerings, with at least one downward camera for precise board positioning, and often an up-facing camera as well to ensure component position and orientation (if not multiple cameras for each purpose). Without these, the machine would be dead reckoning and that can lead to drift over the size of the board and the duration of the placement run as well as axial misalignment. Adding vision shouldn’t be a ground-up effort though, as [Stephen] chose to use OpenPnP to drive the machine and that project already has vision support. This will be much simpler to add when compared to the complexity of the feeders.

[Stephen] admits that much work still needs to be done and he would love to have help dialing in the performance of the feeder design, and fleshing out features on the road to perfection. Although we suspect that as in the early days of bootstrapping 3D printers, a project like this can never be truly finished. At least it’ll make his next run of LED glowties a lot easier to fabricate.

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Iron Pipe Makes A Great Workbench

May 11, 2020 by Jenny List 41 Comments

It’s a frequently encountered problem in any workshop; how do you make a bench? And once you’ve made a bench, how do you put it on wheels to move it about? [Eric Strebel] needed a cart for his laser cutter, so he designed his own in an unexpected material: malleable iron pipe.

The attraction of iron pipe is its ready availability and ease of assembly. [Eric] created a sturdy table complete with a worktop made from a solid door in a very short time. T pieces and joiners were used, along with a hefty set of flanges for the tabletop itself. The casters are the expanding stem variety, with a compressed rubber insert expanding to hold them securely in place.

The result as can be seen in the video below is a really neat trolley for the cutter, followed quickly by another workbench. It would be interesting to know more about this material, parameters such as its wall thickness and lateral strength, because in a table without any cross-bracing it becomes important to avoid an untimely collapse.

The most common material for benches seems still to be wood, indicating that for such a technophile community we can be surprisingly conservative in our choices. Sometimes though, benches are made from the most surprising things.

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No More Floppy Drives For This Agilent Scope

May 10, 2020 by Al Williams 28 Comments

When [kiwih] picked up an Agilent 54621A scope, he was amused that it had a floppy disk. At one time, it was high-tech to use a disk to transfer scope data to your computer. Today, not so much. However, on the back was a serial port. Surely it was possible to read data from there. It is, and what results is a nice walkthrough of finding the port’s info and interfacing with it using Python.

Normally, you’d use the included BenchLinkXL software to grab data from the port, but that software is so old it would not run under Windows 10 or Wine. Searching didn’t turn up much on the serial port, but it did locate a manual for a similar Agilent scope. That manual wasn’t too helpful since it assumed you were connecting via a LAN or USB. However, it did make reference to an older model that was also similar and that was the key to finding a manual that did explain the serial port protocol.

The command set looks suspiciously like SCPI — Standard Commands for Programmable Instruments — which is a layer on top of the GPIB protocol. Many scopes speak that language, so that’s not surprising. That also means if you are in the mood to communicate with an SCPI scope, you might find the code useful, even if you don’t use a serial port or have this exact Agilent model.

SCPI has a lot of uses. For example, try talking to your scope. The cheap Rigol and similar scopes usually have SCPI and you can control and read them using the same kind of techniques.

No Corners Were Cut On This Arduino Circle Cutter

May 8, 2020 by Tom Nardi 9 Comments

Hackers always have their eye out for a good deal, so when [Gadget Reboot] saw a good price on square stickers he had to pull the trigger. There was just one problem: his logo is a circle. He could have rectified the problem with a pair of scissors on a lazy afternoon, but we think building an elaborate circle cutting machine was a much better use of his time.

But this project isn’t just for the Giotto wannabes. Even if you don’t find yourself in need of an infinite supply of perfect paper circles, the video after the break provides an excellent case study in getting stepper motors to do your bidding; whatever that might be. [Gadget Reboot] walks the viewer through the design and construction of a dual stepper motor controller that could be used for a multitude of tasks.

With an onboard Arduino Pro Micro, OLED display, and rotary encoder, this controller just needs some custom software to make your CNC dreams come true. [Gadget Reboot] is even using low-cost optical endstops in this build, which are a great non-contact way of making sure your machine doesn’t go out of bounds. That’s particularly important when the machine happens to be wielding a razor blade.

If you’re a thoroughly modern hardware hacker who prefers using a web browser to twiddling knobs, then perhaps you’d be interested in the WiFi enabled stepper motor controller we covered recently.

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Wooden Sheet Metal Press Tools Make Steel Toecaps

May 7, 2020 by Jenny List 28 Comments

If you have ever looked closely at a typical mass-produced automobile, you will be familiar with pressed-steel panels. Complex curves can be repeated thousands of times over, by putting a sheet of steel between shaped tooling in a press and applying huge force. The same work that would take a skilled panel beater weeks to do by hand, in a second. It’s something [Stuff Made Here] tackled when he wanted to wear a set of Crocs in the workshop, and needed to make the tooling to produce them in his hydraulic press. The resulting video which we’ve posted below the break shows his learning curve, and along the way is a handy primer in sheet metal pressing.

We watch as he discovers the properties of sheet metal under the stress of pressing, how it wrinkles and folds, and how the tool needs careful design and the sheet needs to be securely clamped in place to prevent this. The big surprise is that his tooling is made from CNC-machined wood, while we’re sure that it would wear given repeated use it seems that the forces on the tool are not such as to destroy this material. In the end he’s produced a multi-part tool including both halves of the press tool, a machined guide for the moving part, and a set of substantial sheet metal plates to constrain the material. The steel toecap application may not be everyone’s first idea when it comes to sheet metal forming, but we’re sure this technique could find application in many other projects. It’s a territory into which we’ve edged in the past, but never with pressings this complex.

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Scopetrex Is A Game Console… For Your Oscilloscope!

May 7, 2020 by Jenny List 35 Comments

You’ve always wanted a game console at your bench, but maybe you haven’t had space for a monitor or TV set? Wouldn’t it be useful if the screen you do have on your bench could also play games? [Tube Time] has fixed this problem, with Scopetrex, a vector graphic console for your oscilloscope. In fact, it’s better than just a console, because it’s a clone of the legendary Vectrex, the vector-based console with built-in CRT screen from the 1980s.

The board itself is a slightly enhanced version of the original, offering not extra functionality but the ability to substitute some of the parts for more easily found equivalents. It gives full control over display size and brightness, can use the cheaper 6809E processor and AY-3-9810 sound chip if necessary, and only needs a single 5 volt supply. There’s also a custom controller board, which is handly Vectrex-compatible. All you will need to play Vectrex games on your ‘scope once you’ve built this board, are a copy of the Vectrex ROM, and some games.

The Vectrex holds an enduring fascination for our community, and has appeared here many times. Particularly memorable is a CRT replacement, and then of course there’s the never-released mini Vectrex prototype.

Thanks [Justin List] for the tip.