Automated Cat Feeder Leaves Little To Chance

We often like to say that if something is worth doing, then it’s worth overdoing. This automatic cat feeder built by [krizzli] is a perfect example of the principle. It packs in far more sensors and functions than its simple and sleek outward appearance might suggest, to the point that we think this build might just set the standard for future projects.

The defining feature of the project is a load cell located under the bowl, which allows the device to accurately measure out how much feed is being dispensed by weight. This allows the feeder to do things such as detect jams or send an alert once it runs out of food, as well as easily adjust how much is dispensed according to the animal’s dietary needs. To prevent any curious paws from getting into the machine while it’s doling out the food, the lid will automatically open and close during the filling process, complete with optical sensors to confirm that it moved as expected.

All of the major components of the feeder were printed out on a Prusa i3 MK3S, and [krizzli] says that the feed hopper can be scaled vertically if necessary. Though at the current size, it’s already packing around a week’s worth of food. Of course, this does depend on the particular feline you’re dealing with.

In terms of electronics, the feeder’s primary control comes from an ESP8266 (specifically, the Wemos D1 Mini), though [krizzli] also has a Arduino Pro Mini onboard so there’s a few more GPIO pins to play with. The food is dispensed with a NEMA 17, and a 28-BYJ48 stepper is in charge of moving the lid. A small OLED on the side of the feeder gives some basic information like the time until the next feeding and the dispensed weight, but there’s also a simple API that lets you talk to the device over the network. Being online also means the feeder can pull the time from NTP, so kitty’s mealtime will always be on the dot.

Over the years we’ve seen an incredible array of automatic cat feeders, some of which featuring the sort of in-depth metrics possible when you’ve got on onboard scale. But we can’t help but be impressed with how normal this build looks. If nothing else, of all the feeders we’ve seen, this one is probably the most likely to get cloned and sold commercially. They say it’s the most sincere form of flattery.

Auto-Trickler Gently Doles Out Powder To Assist Reloading

Do you even trickle?

[Eric] does, and like everything else about reloading, trickling is serious business. Getting an exact charge of powder to add to a cartridge is not a simple task, and very tedious when done manually. This smartphone-controlled auto-trickler is intended to make the job easier, safer, and more precise.

Reloading ammunition is a great way for shooters to save money and recycle the brass casings that pile up at the end of a long day at the range. It can be a fairly simple process of cleaning the casings, replacing the spent primers, adding the correct powder charge, and seating a new bullet. It’s all pretty straightforward, but the devil is in the details, especially with the powder charge. A little too much can be a big problem, so tricklers were invented to allow the reloader to sneak up on the proper charge. [Eric]’s auto-trickler interfaces to a digital powder scale and uses a standard cell phone vibration motor to gently coax single kernels of powder from a hopper until the proper charge has accumulated. It’s easier to understand by watching the video below.

The hardware behind the trickler is pretty standard — just a Raspberry Pi Zero to talk to the smartphone UI via Bluetooth, and to monitor and control the scale via USB. [Eric] has made all the code open source so that anyone can build their own auto-trickler, which we applaud; he did the same thing with his rifle-mounted accelerometer. This project might have applications far beyond reloading where precision dispensing is required.

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Let Your Pi Make A Pie Chart For Your Pie

March 14th is “Pi Day”, for reasons which should be obvious to our more mathematically inclined readers. As you are not reading this post on March 14th, that must mean we’re either fashionably late to Pi Day 2019, or exceptionally early for Pi Day 2020. But in either event, we’ve got a hack for you that celebrates the day using two things we have it on good authority most hackers overindulge in: food and needless complexity.

This project comes from [Mike MacHenry], and it’s just as straightforward as it looks. Put simply, he’s using a load cell connected to the Raspberry Pi to weigh an actual pie and monitor its change over time. As the pie is consumed by hungry hackers, a pie graph (what else?) is rendered on the attached screen to show you how much of the dessert is left.

One might say that this project takes a three dimensional pie and converts it to a two dimensional facsimile, but perhaps that’s over-analyzing it. In reality, it was a fun little hack [Mike] put together just because he thought it would be fun. Which is certainly enough of a motive for us. More practically though, if you’re looking for a good example for how to get a load cell talking to your non-edible Raspberry Pi, you could do worse than checking this out.

We’ve also got to give [Mike] extra credit for including the recipe and procedure for actually baking the apple pie used in the project. While we’re not 100% sure the MIT license [Mike] used is actually valid for foodstuffs, but believe it or not this isn’t the first time we’ve seen Git used in the production of baked goods.

Every Shop Needs A Giant Wooden Utility Knife

Generally speaking, we don’t cover that many woodworking projects here at Hackaday. What’s the point? It’s bad enough that wood reminds us of the outside world, but it hardly ever blinks, and forget about connecting it to Wi-Fi. This doesn’t seem to bother you fine readers, so we have to assume most of you feel the same way. But while we might not always “get” large woodworking projects around these parts, we’re quite familiar with the obsession dedication required to work on a project for no other reason than to say you managed to pull it off.

On that note, we present the latest creation of [Paul Jackman], a supersized replica of a Stanley utility knife made entirely out of wood. All wooden except for the blade anyway, which is cut from 1/8″ thick knife steel. That’s right, this gigantic utility knife is fully functional. Not that we would recommend opening too many boxes with it, as you’re likely to open up an artery if this monster slips.

We can’t imagine there are going to be many others duplicating this project, but regardless [Paul] has done a phenomenal job documenting every step of the build on his site. From cutting the rough shape out on his bandsaw to doing all painstaking detail work, everything is clearly photographed and described. After the break there’s even a complete build video.

The most interesting part has to be all of the little internal mechanisms, each one carefully reproduced at perfect scale from different woods depending on the requirements of the component. For example [Paul] mentions he choose white oak for the spring due to its flexibility. Even the screw to hold the knife closed was made out of a block of wood on the lathe.

For whatever reason, people seem to enjoy building scaled up replicas of things. We’ve seen everything from LEGO pieces to gold bars get the jumbo treatment. We suppose it’s easier than the alternative: building very tiny versions of big things.

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3D Printers Get A Fuel Gauge: Adding A Filament Scale To OctoPrint

It seems a simple enough concept: as a 3D printer consumes filament, the spool becomes lighter. If you weighed an empty spool, and subtracted that from the weight of the in-use spool, you’d know how much filament you had left. Despite being an easy way to get a “fuel gauge” on a desktop 3D printer, it isn’t something we often see on DIY machines, much less consumer hardware. But with this slick hack from [Victor Noordhoek] as inspiration, it might become a bit more common.

He’s designed a simple filament holder which mounts on top of an HX711 load cell, which is in turn connected to the Raspberry Pi running OctoPrint over SPI. If you’re running OctoPrint on something like an old PC, you’ll need to use an intermediate device such as an Arduino to get it connected; though honestly you should probably just be using a Pi.

On the software side, [Victor] has written an OctoPrint plugin that adds a readout of current filament weight to the main display. He’s put a fair amount of polish into the plugin, going through the effort to add in a calibration routine and a field where you can enter in the weight of your empty spool so it can be automatically deducted from the HX711’s reading.

Hopefully a future version of the plugin will allow the user to enter in the density of their particular filament so it can calculate an estimate of the remaining length. The next logical step would be adding a check that will show the user a warning if they try to start a print that requires more filament than the sensor detects is currently loaded.

This is yet another excellent example of the incredible flexibility and customization offered by OctoPrint. If you’re looking for more reasons to make the switch, check out our guide on using OctoPrint to create impressive time lapse videos of your prints, or how you can control the printer from your mobile device.

Linear Clock Is A Different Way To Look At Time

There are usually two broad user interfaces for clocks. On the one hand you’ve got the dial clock, the default display for centuries, with its numbered face and spinning hands. The other mode is some form of digital clock, where the current time is displayed directly as alphanumeric characters. They’re both useful representations of time, but they both have their limits.

Here’s a third model — the linear clock. [Jan Derogee] came up with it thanks to the inspiration of somewhat dubious run-ins with other kinds of clocks; we feel like this introductory video was made with tongue firmly planted in cheek. Whatever the inspiration, we find this idea clever and well executed. The running gear of the clock is just a long piece of M6 threaded rod and a stepper motor. A pointer connected to a nut rides on the rod, moving as the stepper rotates it. There are scales flanking the vertical rod, with the morning hours going up the left side and afternoon hours coming down the right. The threaded rod rotates one way for twelve hours before switching to the other direction; when the rotation changes, the pointer automatically swivels to the right scale. For alarms, [Jan] has brass rods running along each scale that make contact with the pointer; when they encounter a sliding plastic insulator to break the contact, it triggers an alarm. An ESP8266 controls everything and plays the audio files for the alarm.

Unusual clocks seem to be a thing with [Jan]. His other builds include this neat phosphorescent clock and YouTube subs counter, which is sure to turn heads along with this clock.

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Hackaday Links: March 4, 2018

Guess what’s happening next weekend? The SoCal Linux Expo. SCALE is in its 16th year, and is the second greatest convention happening this year at the Pasadena Convention Center. The first, of course, is AlienCon this summer, with a special guest appearance by the guy with the hair on Ancient Aliens. What’s cool at SCALE? Tons of stuff! Tindie and Hackaday will have a booth, you’ll be able to check out the new stuff from System 76, and this is where I first picked up my most cherished possession, a Microsoft (heart) Linux sticker. NEED A TICKET? Cool, use the code ‘HACK’ to get 50% off!

[Muth] over on hackaday.io has been working on a very, very, very cool high voltage display. It’s a ИГГ1-64x64M, or a Gazotron, or something. What is it? It’s a two-color (green and red) 64×64 pixel VFD bitmap display. You want the king of all vacuum-based displays? Here you go. Progress on driving this display is slow, but it’s happening, and it will result in the coolest clock ever created.

Need a pick and place machine? Don’t want to shell out thousands for a Neoden? Here’s an Indiegogo campaign for the Open Placer, a machine that works with OpenPNP software. It’s got vision and a 295x195mm working area.

A few months ago, news came from Havana that the US embassy was under attack. Staffers at the US embassy in Cuba were feeling sick and apparently suffered neurological damage. Explanations ranged from poisoning to some sort of non-lethal weapon. Now, there might be a banal explanation. Researchers at the University of Michigan think it could simply be two ultrasonic sensors placed just the right distance apart. Acoustic interference happens, and that inaudible 35kHz signal becomes a maddening audible signal.

Last week, we had a great talk with OSH Park about PCBs. These Hack Chats are getting out of control, but at least we have a transcript. The biggest takeaway? They’re out of jellybeans, but OSH Park is working on new stickers.

Open Hardware Summit is the greatest con for all things Open Hardware. This year, it’s going to be in Boston. The Summit will be held on September 27th, 2018 at MIT Stratton Student Center. If you’d like to get there a week and a half early, the MIT ham flea market is the third Sunday of the month.