Turning A Pair Of Syringes Into A Tiny Water Pump

July 31, 2022 by Danie Conradie 6 Comments

There is something inherently fascinating about tiny mechanical devices, especially when you’re used to seeing much larger versions. This is the case with [Penguin DIY]’s tiny centrifugal water pump built from 5 ml syringes.

The pump is powered by a small 8 mm diameter brushed DC motor, likely the same type that is used for small toy-grade quadcopters. The tiny impeller is a section of the syringe’s original plunger, with its cross-shaped body acting as the impeller blades. [Penguin DIY] first experimented with the original plunger seal to protect the motor from water, but it quickly melted from friction with the spinning shaft. Silicone sealant was used instead, and the motor shaft was covered with a layer of oil to prevent the sealant from sticking to it. Then the blob of sealant was flattened with a translucent plastic disc to allow clearance for the impeller.

A hole was drilled in the side of the syringe where the impeller sits, and a nozzle cut from the tip of another syringe was glued in place as the outlet. It’s notoriously difficult to get anything to stick to polypropylene syringes, but [Penguin DIY] says in the comments he was able to find an “organic superglue” that worked. With the motor and impeller inserted, the remaining space was also sealed with silicone.

This tiny pump packs a surprising amount of power, and was able to empty a 1.5 l bottle in about one minute with enough pressure to send the jet of water flying. There are still some issues that need to be addressed, though. With the motor completely sealed, it could burn itself quite quickly. A commenter also mentioned that it might suck water into the motor past the shaft after a hot run, as the air inside the motor cools and contracts. Even so, this little pump might be practical for applications that only require short runs, like watering potted plants. If you need more power you could always 3D print a larger pump.

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Large Format 3D Printer Is A Serious Engineering Challenge

July 27, 2022 by Danie Conradie 14 Comments

When you want to build a large format 3D printer, you can’t just scale up the design of a desktop machine. In an excellent four-part build series (videos after the break), [Dr. D-Flo] takes us through all the engineering challenges he had to contend with when building a 3D printer with a 4x4x4 ft (1.2 m cube) print volume.

For such a large print volume you won’t be printing with a 0.4 mm nozzle. The heart of the printer is a commercial Massive Dimension MDPH2 pellet extruder, capable of extruding ~1 kg of plastic per hour through 1.5 mm to 5 mm nozzles. To feed the extruder, [Dr. D-Flo] used a Venturi vacuum system to periodically suck pellets from a large hopper. The system is driven by compressed air, which can introduce moisture back into the carefully dried pellets. To reduce the humidity levels, the compressed air passes through a series of vertical aluminum tubes to allow moisture to condense and drain out the bottom.

At 8.4 kg, it needs a powerful motion platform to move it. [Dr. D-Flo] went with a stationary bed design, with the extruder pushed around by seven high torque NEMA23 motors on a large gantry built from C-beam aluminum extrusions. A machine this size needs to be very rigid with well-fitting parts, so [Dr. D-Flo] made heavy use of CNC machined aluminum parts.

To allow dynamic bed leveling, [Dr. D-Flow] made use of a Quad Gantry Leveling (GQL) scheme. This means that each of the four Z-actuators will dynamically adjust its position based on inputs from the leveling probe. The avoid stressing the corner mountings that hold the X-Y gantry to the Z carriage plates, he used radial spherical bearings at the mounting points to allow a few degrees of play.

The build plate consists of an aluminum plate bolted onto the base in 25 positions with springs for adjustability. A massive 6000 watt 220 V heating pad sticks to the bottom, while the actual printing surface is a large sheet of borosilicate glass. One major concern was the deflection of the build plate when heated to working temperature, but with all the adjustment options [Dr. D-Flo] was able to get height variation down to about 0.25 mm. This is within the acceptable range when printing with layer heights of 1 mm or more.

We’ve featured large scale 3D printers in the past, but none are quite as big the University of Maine’s building-sized 3D printer that can print a motorboat in one piece.

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Omnidirectional Walker With Wheeled Feet

July 26, 2022 by Danie Conradie 4 Comments

[James Bruton] is on a quest to explore all the weird and wonderful methods of robot locomotion, and in his latest project created an omnidirectional walker that can move in any direction instantaneously.

The walker actually makes use of three independent four-legged Strider mechanisms, connected in a triangle at 120deg. Wheels are attached to the bottom of each leg, oriented at a right angle to the leg’s plane of motion to allow the foot to slide. Varying the relative speed and direction of each of the mechanisms lets the robot move in any direction, similar to his ball-wheeled robot. Each strider mechanism uses a single motor and looks similar to Strandbeest walkers, but it lifts its feet to traverse rougher terrain. [James] demonstrates this with some obstacles, and found that moving in such an orientation that all three sets of legs provide the best results.

[James] planes to build a larger rideable version, but we think he should mount a chest of Sapient Pearwood to carry all his stuff and name it The Luggage.

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Automated Hotend Swapping For Less Wasteful Multicolor Printing

July 24, 2022 by Danie Conradie 16 Comments

Multicolor printing on FDM machines can be tricky to get working flawlessly, and purging hotends when changing colors can end up wasting a lot of filament and material. To solve this problem for the popular Prusa i3 and Ender 3 printers, [BigBrain3D] developed the Swapper3D, an automated system that swaps the entire hotend when the material is changed, eliminating the need for purging almost entirely. Video after the break.

The Swapper3D works very similarly to the tool-changing systems on CNC machines, and is just as satisfying to watch. A large circular carousel on the side of the machine holds up to 25 hotends, and in practice, a pair of robotic arms pop out the previous hotend, cut the filament, and load up the specified hotend from the carousel. This means you can have a separate hotend for each color or type of filament. Since most existing hotends also integrate the heating element, [BigBrain3D] created a special hotend assembly that can be robotically removed/inserted into the heater block.

The Swapper3D is designed to be used with existing filament changers like the Prusa MMU and the Mosaic Palette. Using these systems involves a lot of purging, to the point where you sometimes end up using more filament during purging than you need for the actual part. On one five-color demo print, the Swapper3D reduced the print time by 45% and the filament used by a massive 86%. It also helps to eliminate problems like stringing and color fading in multicolor prints. With those advantages, it looks like the Swapper3D might be a worthwhile upgrade if you do a lot of multi-color printing, even though it adds quite a bit of complexity to the printer.

For larger, more expensive machines, swapping the entire toolhead is becoming more popular, with even E3D stepping into the fray.

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Stackable 3D-Printed Gearbox For Brushless Motor

July 24, 2022 by Danie Conradie 11 Comments

Affordable brushless motors are great for a variety of motion applications, but often require a gearbox to tame their speed. [Michael Rechtin] decided to try his hand at designing a stackable planetary gearbox for a brushless motor that allows him to add or remove stages to change the gear ratio.

The gearbox is designed around a cheap, 5010 size, 360 KV, sensorless motor from Amazon. Each stage consists of a 1:4 planetary gear set that can be connected to another stage, or to an output hub. This means the output speed reduces by a factor of four for each added stage. Thanks to the high-pressure angle, straight-cut teeth, and fairly loose clearances, the gearbox is quite noisy.

To measure torque, [Michael] mounted the motor-gearbox combo to a piece of aluminum extrusion, and added a 100 mm moment arm to apply force to a load cell. The first test actually broke the moment arm, so a reinforced version was designed and printed. The motor was able to exert approximately 9.5 Nm through the gearbox. This number might not be accurate, since sensorless motors like this one can not provide a smooth output force at low speeds. As [Michael] suggests, adding a sensor and encoder would allow for better testing and low speed applications. Check it out in the video after the break.

We’ve featured a number of [Michael]’s projects before, including a bag tracking corn hole board, and a 3D printed linear actuator. Continue reading “Stackable 3D-Printed Gearbox For Brushless Motor” →

Turn Drone Into A Large Propeller To Increase Hover Efficiency

July 24, 2022 by Danie Conradie 42 Comments

Multirotor drones are significantly more popular than conventional helicopter designs for many reasons, which do not include efficiency. Making use of the aerodynamic effects behind this, [Nicholas Rehm] was able to significantly increase the efficiency of his experimental tricopter by turning it into one large spinning propeller.

Since aerodynamic drag is proportional to velocity, a small, high-RPM propeller will require more power to produce the same thrust as a large, low-RPM propeller. With this in mind, [Nicholas] built a tricopter that can rotate all three long arms together using a single servo, giving it very aggressive yaw control. By attaching a wing to each of the arms, it becomes a large variable pitch propeller powered by tip thrusters.

To measure the efficiency of the craft, a small lidar sensor was added to allow accurate PID altitude control. While keeping the drone at a constant altitude a few feet off the ground, [Nicholas] measured the power draw of the motors in a hover, and then let the drone spin around its yaw axis up to almost 5 rev/s.

At a spin rate of 4 rev/s, the power draw of the motors was reduced by more than 60%. Even compared to the drone without the added weight of the wings, it still used 50% less power to maintain altitude.

Since [Nicholas] hadn’t yet implemented horizontal position control while spinning, the length of each test run was limited by the wind drift. He plans to solve this, and also do some testing of the drone in horizontal flight, where the added airfoils will also increase efficiency.

We’ve featured a few of [Nicholas]’ flying machines here on Hackaday, including a foam F-35 VTOL and a cyclocopter. Most of his aircraft run his open source dRehmFlight flight stabilization, created specifically for hacking.

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Farm Data Relay System: Combine LoRa And 2.4 Ghz Networks Without WiFi Routers And Cloud Dependence

July 2, 2022 by Danie Conradie 25 Comments

Setting up a wireless sensor network over a wide area can quickly become costly, and making everything communicate smoothly can be a massive headache, especially when you’re combining short range Wi-Fi with long range LoRa. To simplify this, [Timm Bogner] created Farm Data Relay System which simplifies the process of combining LoRa, 2.4Ghz modules and serial communications in various topologies over wide areas.

The FDRS uses a combination of ESP32/8266 sensor nodes for short range, and LoRa nodes for long range. The ESP nodes use Espressif’s connectionless ESP-NOW peer-to-peer protocol on which allow multiple ESP boards to communicate directly without the need for a Wi-Fi router. The ESP modules can have one of 3 roles, nodes, repeaters or gateways, and gateways and repeaters share the same code. Nodes take sensor inputs, and are configured to each have a unique READING_ID.

Relays just retransmit ESP-NOW packets to extend the network range, while gateways convert packets between ESP-NOW, MQTT over Wi-Fi, LoRa or serial messages as required. Repeaters and gateways each have a unique UNIT_MAC for addressing. The code that handles communication for the ESP devices is simple and well documented, so you only need to set a few configuration values, and then can focus your efforts on the code required for your specific application.

The hub of the system is a Raspberry Pi running Node-RED which acts as the final MQTT gateway and connects to the ESP MQTT gateways. This means that all the action happens in the local network, without being dependent on an internet connection and cloud service. However, it can still send and receive data over the internet using MQTT or any other protocol as required. Node-RED makes it particularly easy to build custom automations and interfaces.

In the video after the break, Andreas Spiess, the man with the Swiss accent, who also has a hand in the project, goes over all the features, setup and caveats.

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