Gone fishin’

Fishing in Minecraft isn’t exactly difficult. Once you craft a fishing rod, it’s mostly a question of waiting for something to bite, and right-clicking to reel it in, then right-clicking a second time to cast the line back out again. It makes “easy” look difficult.

Unfortunately, until you acquire a fully-enchanted fishing rod (or at least Lure III), it’s also about as engaging as watching paint dry, but still requires at least a good part of your attention, to avoid missing any fish.

Yes, it’s a sterile, isolated pool. No, that doesn’t matter. #minecraftlogic

Fishing in Minecraft does, however, have in-game advantages. There’s lots of stuff in there — some of which (including important “treasure” enchantments such as Mending) can’t easily be found in other ways. And it’s fun to see what new rare items have been added in recent versions of the game.

Fortunately, the fishing algorithm is simple enough that it can be readily automated:

  • Wait for a loud sound (the “fish” biting);
  • Right-click the mouse;
  • Wait about 250ms;
  • Click it again to re-cast;
  • Wait about two seconds to re-arm.

The Arduino Leonardo is an Arduino board specifically designed to allow the easy generation of mouse and keyboard input to a PC. With a few lines of C++ code, the Leonardo (attached via USB) can emulate a mouse and send right or left clicks and/or mouse movement commands.

A short sketch and attached microphone sensor later, and the Leonardo is on duty in front of one of the speakers, listening for the sound of a strike. Now the fish catch themselves.

The microphone sensor is from one of those cheapo sensor kits on Amazon.
I forget which one, but it doesn’t really matter.

It’s a temporary project (and the $30 or so cost for the Leonardo is a bit expensive for a dedicated Minecraft fishing robot) — but it’s a fun example of what can be done on a whim with even very simple microcontroller electronics. Technologies like USB have many layers of complexity. They make lots of things possible, but are inherently complex to use, out of the box. Progress speeds up when those technologies are packaged in easy-to-use modules.

Civilization advances by extending the number of important operations which we can perform without thinking about them.

–Alfred North Whitehead

Posted in Analog, Arduino, Audio, C, Digital, Games, Minecraft | Leave a comment


Talk about a curb alert.

A friend of a friend had a 3D printer which needed some repairs, so he was planning to put it out on the curb. He contacted me at my friend’s suggestion and gave it to me to fix up. (Thanks, Dan and Grandin!)

Large printer is large. (Banana for scale.)

The printer turned out to be a “Mankati Fullscale XT Plus” printer. (Yeah, I hadn’t heard of Mankati, either.) They may not have great name recognition (and it appears they may be out of business at this point), but they built a very solid printer. Not to mention a rather large one. 36kg doesn’t sound like much, but this thing is a beast. The build volume is insane for a hobbyist / consumer 3D printer — 260x260x300mm. (Yes, the Z axis is the largest.) This is over 20 liters — something like 2.3 times the size of my next-largest printer. It’s insane — and it can get away with it because it’s mostly enclosed, and …

Similar to Ultimaker-style machines, the XT Plus uses a CoreXY scheme, where the print head moves in X and Y, and the bed moves in Z. This has the advantage of moving the actual part hardly at all, while the (more secure) print head moves around rapidly. I’ve wanted to play with one for a while. It should certainly cut down on bed adhesion problems.

CoreXY means the print head moves in X and Y, and the part in Z.
This greatly reduces stresses on the part base due to shaking in Y.

Like pretty much all CoreXY machines, the XT Plus uses a Bowden extruder setup, with two NEMA-17 extruder steppers mounted neatly on the back case. These drive all-metal geared extruders which look as professional as anything I’ve seen on a 3D printer. From the extruders, the filament follows a Bowden tube to the print head, which rides on a set of Cartesian rails at the top of the printer.

The Bowden tubes are fed by two solid metal geared extruders.

The gantry appears to be a machined block of aluminum, with feedthrough holes for the filament and mounting holes for the hot ends and fan shroud. Like the rest of the mechanics, it looks and feels very solid.

When I got the printer, the left hot end had been disassembled, possibly because one of the wires to its thermistor had broken, causing the printer to throw an error. A quick solder job and some shrink tubing solved that.

It was at about this point that I noticed that this was a 3mm filament machine. I’m a 1.75mm shop — 1.75mm extruders, 1.75mm throats, 1.75mm nozzles … so 3mm hardware might as well have been built by aliens. At least it came with two reels of filament. I just had to hope I wouldn’t find any serious problems with the hot end, or I’d be ordering hardware before printing anything (hey, still an awesome deal.)

There’s nothing wrong with 3mm filament — and several reasons to prefer it. The vast majority of hobbyist 3D printers use 1.75mm, however, so it’s much easier to find parts for that format. It’s kind of like shopping for Beta videotapes, after VHS won the format war. They may be better quality, but your selection is lacking.

Fortunately, the hardware was all in good shape. After reassembly, the hot end was back up and extruding.

Extruder #1 is up and running. (Extruder #2 may get converted to 1.75mm.)

I initially tried printing one of the test pieces on the included SD card — a model couch sized as if for a dollhouse. I selected the 250u resolution one, and the printer started to do its thing. Everything looked OK except the #2 nozzle was dragging across the print, tearing up whatever had just been laid down.

Walk before you run, I figured, and once the hot end had cooled down, I removed the second hot end. A second try at the built-in couch model produced a good print at a surprisingly high speed.

The next thing I wanted to try was to get Simplify3D to talk to it. I had read that USB communication wasn’t possible (even though the printer has a visible USB port), and that prints had to be copied via SD card.

Apparently you can’t believe everything you read on the Internet, because S3D had no problems at all recognizing the printer and sending it commands. I was initially concerned about managing profiles and printer settings, since the Mankati is so different from either of my other printers, but creating a new S3D process solved that nicely. I wasn’t initially sold on the whole idea of processes — but I’m convinced.

Now that I had S3D set up to talk to the printer, the next obvious step was to print a 3DBenchy. Other than some horrendous stringing (to be expected on a Bowden running non-Bowden slicer settings), it turned out pretty well.

Next, I tried a high-resolution test: Wild Rose Builds’ interlocking cube puzzle, at 100u resolution. This took several hours even at 70mm/sec and high acceleration, but turned out nicely, with very smooth, even walls.

So, the verdict: It’s big, it’s heavy, it’s loud, and it’s certainly weird, but it’s mechanically a very big, solid, fast, capable machine — and those are some of the hardest (most expensive) things to get right in 3D printers. It’s too bad Mankati is out of business — but as modular as 3D printers are and as solidly built as this one is, at least this particular printer should be around for a while.

Posted in 3D Printing, Reviews, Tools | Tagged , , , , | Leave a comment

Apollo 11

Fifty years ago today, humans did something pretty cool. We managed to land two of us on the Moon and then bring them back home safely. Half a century later, it’s still an impressive accomplishment — and one which we haven’t duplicated since that era.

Follow the descent from Lunar orbit to Tranquility Base in “real time” (plus exactly fifty years) by starting the following video clip at 19:59:42 UTC today (July 19, 2019). This is equivalent to 15:59:42 EDT for the U.S. East Coast; 14:59:42, 13:59:42, and 12:59:42 respectively for CDT, MDT, and PDT. (If you’re from one of those enlightened areas that don’t use Daylight Subverting Time, you’re probably smart enough to understand UTC, too.)

Start this video at eighteen seconds before 4PM Eastern on 2019-07-20
to follow along “live” exactly fifty years later.

(Spoiler alert: They almost run out of fuel, but they make it okay.)

Posted in Aviation, Current Events, Nostalgia | Leave a comment

Reverse Shoplifting

Engineers love gadgets. Sometimes, we even anthropomorphize them a bit and get attached to pieces of vintage gear that we don’t really use anymore. The lure of the New And Shiny is strong, yes, but there’s something about the glow of vacuum tubes, too.

For many of us, though, it’s somehow okay if we know that a beloved piece of gear — or even just a nostalgic example of 1980s-era DIP memory — is going to a good home. It’s easier to part with a vintage Tektronix ‘scope if it means that a new electronics hobbyist will be able to use it to see the angry pixies in the wires. At least it’s not going into the trash.

Reusing vintage gear is what hamfests are all about. Even if you’ve been in the hobby for decades, a good hamfest will mean you’ll see at least one piece of gear that takes you a moment to identify — and probably, several new variations on tools you didn’t know existed. Field strength meters powered by the radio signals they monitor. Analog computers, designed to calculate how much feed to give your dairy cattle (I really hope that’s still in a box around here somewhere). Hopefully-declassified military surplus gear. It’s all fascinating.

The downside is that, for most people, space is limited. At some point, cubic-meters-in must not exceed cubic-meters-out. Hamfests provide the best way to rehome surplus gear — but sometimes, nobody is looking for the particular boat anchors that you brought to offload. After a few trips back and forth, you wish they weren’t taking up space — but you just don’t have the heart to put that vintage HP signal generator in the trash. What To Do?

The solution — Reverse Shoplifting — is one of the coolest, if somewhat dubious, Chaotic Good traditions I’ve come across. In the course of wandering around a hamfest, it’s not unusual to see an interesting item for sale and want to take a closer look. (That’s why you’re there in the first place, after all!) So you set down the random piece of gear you were ostensibly carrying back to your car after having purchased it, and take a look at what the seller has on the table. Maybe you even buy it. After all, it got your attention.

In the confusion, it’s not unheard of to forget the item you were originally carrying, and absentmindedly wander off, leaving it there. Perhaps this is the Universe’s way of telling you that your boat anchor had found its new owner. Perhaps entropy will decrease a tiny bit more slowly when a piece of gear gets another shot at usefulness instead of heading to a landfill.

Or maybe, you think to yourself as you slip away as nonchalantly but quickly as you can, you’ll actually have room in the car for that antenna tower the guy in the cube van was selling.

This post is dedicated to the memory of my Elmer: Frank H. Gentges AK4R/K0BRA.
Thanks for teaching me not just the nuts and bolts, but the lore, too.

Posted in HOW-TO, Humor, Lore, Nostalgia | Leave a comment