Better 3D Printing through Magnets

Just like Goldilocks found some porridge too hot and some too cold, 3D printers often have beds that don’t stick well enough or stick too well. A few weeks ago I switched two of my three printers to use magnetic beds and thought I’d share with you how that worked out. Spoiler alert: like most things it has its plusses and minuses.

It isn’t a secret that 3D printing is not a plug-and-play operation, especially at the price most of us are willing to pay for printers. There are lots of variables to get right: temperature, speeds, bed leveling, and a bunch of other things. However, one of the things that vexes many people is the relationship between getting that first layer to stick and being able to get the print off the bed when you are done. It is hard to find a happy medium. If the first layer won’t stick, you print is doomed. If the first layer sticks too well, you are likely to damage the part or your fingers getting it removed. I switched to BuildTak surfaces long ago, and many people like PEI. But it is sometimes hard to get a big part removed. A few weeks ago, I took the plunge and bought some magnetic build surfaces for two of my printers. These were “no name” inexpensive affairs from Ali Express.

The idea is simple. There are two sheets that look like a rubberized plastic and have magnetic properties. One piece has some 3M adhesive on the back. The other has one surface that resembles BuildTak. Once you glue down the one sheet you leave it alone. Then you put the other sheet on top and print on it. When you are done, you can pull the sheet out and flex it to pop the print off. That’s the theory, anyway. Continue reading “Better 3D Printing through Magnets”

An Integrated Electromagnetic Lifting Module for Robots

The usual way a robot moves an object is by grabbing it with a gripper or using suction, but [Mile] believes that electromagnets offer a lot of advantages that are worth exploring, and has designed the ELM (Electromagnetic Lifting Module) in order to make experimenting with electromagnetic effectors more accessible. The ELM is much more than just a breakout board for an electromagnet; [Mile] has put a lot of work into making a module that is easy to interface with and use. ELM integrates a proximity sensor, power management, and LED lighting as well as 3D models for vertical or horizontal mounting. Early tests show that 220 mW are required to lift a 1 kg load, but it may be possible to manage power more efficiently by dynamically adjusting drive voltage depending on the actual load.

[Mile]’s focus on creating an easy to use, integrated solution that can be implemented easily by others is wonderful to see, and makes the ELM a great entry for The Hackaday Prize.

Beverage Holder of Science

The folks at [K&J Magnetics] have access to precise magnetometers, a wealth of knowledge from years of experience but when it comes to playing around with a silly project like a magnetic koozie, they go right to trial and error rather than simulations and calculations. Granted, this is the opposite of mission-critical.

Once the experimentation was over, they got down to explaining their results so we can learn more than just how to hold our beer on the side of a toolbox. They describe three factors related to magnetic holding in clear terms that are the meat and bones of this experiment. The first is that anything which comes between the magnet and surface should be thin. The second factor is that it should be grippy, not slippy. The final element is to account for the leverage of the beverage being suspended. Say that three times fast.

Magnets are so cool for anything from helping visualize gas atoms, machinists’ tools, and circumventing firearm security features.

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Mechanisms: The Reed Switch

Just about everywhere you go, there’s a reed switch nearby that’s quietly going about its work. Reed switches are so ubiquitous that you’re probably never more than a few feet away from one at any given time, especially at home or in the car. You might have them on your doors and windows as part of a burglar alarm system. They keep your washing machine from running when the lid is open, and they put your laptop to sleep when you close the lid. They know if the car has enough brake fluid and whether or not your seat belt is fastened.

Reed switches are interesting devices with a ton of domestic and industrial applications. We call them switches, but they’re also sensors. In fact, they only do the work of a switch while they can sense a magnetic field. They are capable of switching AC or DC at low and high voltages, but they don’t need electricity to work. Since they’re sealed in glass, they are impervious to dirt, dust, corrosion, temperature swings, and explosive environments. They’re cheap, they’re durable, and in low-current applications they can last for about a billion actuations.

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Printed It: Do More with Lockable Ball And Socket Helping Hands

In one hand you hold the soldering iron, in the other the solder, and in two more hands the parts you’re trying to solder together. Clearly this is a case where helping hands could be useful.

Magnifying glass with helping hands
Magnifying glass with helping hands

Luckily helping hands are easy to make, coolant hoses will do the job at under $10. Attach alligator clips to one end, mount them on some sort of base, and you’re done. Alternatively, you can steal the legs from an “octopus” tripod normally used for cell phones. So why would you 3D print them?

One reason is to take advantage of standardized, open source creativity. Anyone can share a model of their design for all to use as is, or to modify for their needs. A case in point is the ball and socket model which I downloaded for a helping hand. I then drew up and printed a magnifying glass holder with a matching socket, made a variation of the ball and socket joint, and came up with a magnetic holder with matching ball. Let’s takea  look at what worked well and what didn’t.

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Roll Your Own Magnetic Encoder Disks

[Erich] is the middle of building a new competition sumo bot for 2018. He’s trying to make this one as open and low-cost as humanly possible. So far it’s going pretty well, and the quest to make DIY parts has presented fodder for how-to posts along the way.

One of new bot’s features will be magnetic position encoders for the wheels. In the past, [Erich] has used the encoder disks that Pololu sells without issue. At 69¢ each, they don’t exactly break the bank, either. But shipping outside the US is prohibitively high, so he decided to try making his own disks with a 3D printer and the smallest neodymium magnets on Earth.

The pre-fab encoder disks don’t have individual magnets—they’re just a puck of magnetic slurry that gets its polarity on the assembly line. [Erich] reverse-engineered a disk and found the polarity using magnets (natch). Then got to work designing a replacement with cavities to hold six 1mm x 1mm x 1mm neodymium magnets and printed it out. After that, he just had to glue them in place, matching the polarity of the original disk. We love the ingenuity of this project, especially the pair of tweezers he printed to pick and place the magnets.

Rotary encoders are pretty common in robotics applications to detect and measure wheel movement. Don’t quite recall how they work? We’ll help you get those wheels turning.

via Dangerous Prototypes

Making A Motorized Turntable Portable

[Robin Reiter] needed a better way to show off his work. He previously converted an electric TV stand into a full 360-degree display turntable, but it relied on an external power supply to get it spinning. It was time to give it an upgrade.

Putting his spacial organization skills to work, [Reiter] has crammed a mini OLED display, rotary encoder, a LiPo 18650 battery and charging circuit, a pair of buck converters, a power switch, and an Arduino pro mini into the small control console. To further maximize space, [Reiter] stripped out the pin headers and wired the components together directly. It attaches to the turntable in question with magnets, so it can be removed out of frame, or for displaying larger objects!

When first powered on, the turntable holds in pause mode giving [Reiter] time to adjust the speed and direction. He also took the time to add an optical rotary encoder disk to the turntable and give the gearing a much needed cleaning. Check out the project video after the break!

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