Dog-Or-Catapult Controls The Speed Of The Feed

[NathanKing] has a cute, rambunctious pupper who eats way too fast for her own good. He’s tried various distribution methods intended to get her to slow down, but she’s just too excited to eat. [Nathan]’s latest solution is to launch the food piece by piece using a catapult. The dog loves the gamified feeding method, which is sort of like one-way fetch. She gets a bit of exercise, and everyone is amused for the half hour it takes to fling 1.5 cups of food one piece at a time.

Electronics-wise, this food flinger doesn’t use much more than three servos and an Arduino Uno. Servo #1 pulls the arm back until it hits a limit switch. Servo #2 holds the arm down , and servo #3 rotates the food tube until it drops a unit of kibble into the spoon. Then servo #2 lets the arm go, and the tasty morsel flies about 30 feet (10 meters).

[Nathan] doesn’t offer step-by-step instructions, but there is more than enough detail to replicate this project. He used what he had on hand, such as scrap aluminium from another project for the frame. Future plans include swapping out the 6V lantern battery for rechargeable AAs, and downsizing to a Nano. We’ve fetched a couple of videos for you and thrown them in after the break. Go get ’em, reader!

Pets need plenty of water, especially during the summer. Here’s a no-sweat automatic watering solution we saw a few years ago.

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Hackaday Prize Entry: 3D Printed Linear Actuator Does 2kg+

The rabbit hole of features and clever hacks in [chiprobot]’s NEMA17 3D Printed Linear Actuator is pretty deep. Not only can it lift 2kg+ of mass easily, it is mostly 3D printed, and uses commonplace hardware like a NEMA 17 stepper motor and a RAMPS board for motion control.

The main 3D printed leadscrew uses a plug-and-socket design so that the assembly can be extended easily to any length desired without needing to print the leadscrew as a single piece. The tip of the actuator even integrates a force sensor made from conductive foam, which changes resistance as it is compressed, allowing the actuator some degree of feedback. The force sensor is made from a 3M foam earplug which has been saturated with a conductive ink. [chiprobot] doesn’t go into many details about his specific method, but using conductive foam as a force sensor is a fairly well-known and effective hack. To top it all off, [chiprobot] added a web GUI served over WiFi with an ESP32. Watch the whole thing in action in the video embedded below.

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Shapeoko 2 Mods: Dust Mitigation and Limit Switches

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Not long ago the Shapeoko 2 came out. In case you missed it, the Shapeoko 2 is the 2nd generation bench-top CNC Router of the namesake. All axes roll on Makerslide and v-wheels. The X and Y axes are belt driven, power is transmitted to the Z axis by lead screw.

As with most products, there will be people who must hack, mod or upgrade their as-received item.  If you are a regular Hackaday reader, you are probably one of those people. And as one of those people, you would expect there have been a few individuals that have not left this machine alone.

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Chinese 3020 CNC Machine Gets Some Upgrades

If you frequent any CNC Forums out on the ‘web you’ll find that these Chinese 3020 CNC routers are generally well received. It is also common opinion that the control electronics leave something to be desired. [Peter]’s feelings were no different. He set out to make some improvements to his machine’s electronics such as fixing a failed power supply and adding PWM spindle control and limit switches.

[Peter] determined that the transformer used in the power supply was putting out more voltage from the secondary coil than the rest of the components could handle. Instead of replacing the transformer with another transformer, two switch mode power supplies were purchased. One powers the spindle and the other is for the stepper motors. So he wasn’t guessing at the required amperage output of the power supplies, [Peter] measured the in-operation current draw for both the steppers and spindle motor.

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Hall effect limit switches for a 3D printer

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We’re used to thinking of limit switches as a mechanical device that cuts the motor connection before physical damage can occur. [Anthony] decided to try a different route with this project. He built this set of no-contact limit switches using a hall effect sensor. The small black package sticking out past the end of the protoboard is the sensor. It is used to detect a magnetic field.

[Anthony] chose to use an Allegro A3144 sensor. Apparently it is no longer in production but was easy to find for a song and dance on eBay. When thinking about the design he decided to add two LED indicators, one lights when the switch is open and the other when it has been tripped. This would have been easy to do with just one LED, but he needed to add more parts to get both working. In the lower left corner of the protoboard you can see the configurable gate device (74LVC1G58) he added to monitor the hall effect sensor and switch the output and LEDs accordingly.