MDF Omniwheel Uses No Metal or Plastic

What’s better than a caster? An omniwheel. These wheels are like a big wheel with little wheels at different angles that can roll in any direction. [Sonodera] built an omniwheel out of laser cut MDF. MDF–or Medium Density Fiberboard–makes up all the parts of the wheel. There’s no plastic or metal at all.

[Sonodera’s] wheel is more of a passive design like a caster. It would be possible to drive the wheel through the center in two directions, but the right-angle rollers are passive.

We’ve seen several robots with omniwheels before. In fact, this tripod-inspired robot also has passive rollers and the three-legged design takes advantage of them (the so-called Kiwi drive). Some schemes combine multi-directional wheels with conventional wheels (usually the standard wheels are in the center). There are other multi-directional wheel designs out there, including the Mecanum wheel. You can see a video of the MDF wheel in action, below.

Clearly the Best Way to Organize SMD Parts

Have some plexiglas (acrylic) leftovers lying around? Well, they could be put to good use in making this SMD organizer. It comes in handy if you deal with a lot of SMD components in your work. No longer will you waste your time trying to find a 15K 1206 resistor, or that BAS85 diode… or any other component you can think of soldering on the PCB. The basic idea is fairly straightforword, which helped keep this short.

2SMD resistors are packed in thick paper tapes that don’t bend easily, and thus need larger containers than other components, which are packed mainly in flexible PE tapes. The first version of this organizer was built with a 96mm diameter space for resistors and 63mm diameter for other components, but it seems that there is no need for such large compartments. If I were to make it again, I would probably scale everything down to about 80% of it’s current size.

The best way to join all plexiglass parts is to use four M4 threaded rods. There is also a 1.5mm steel rod which holds SMD tape ends in place and helps to un-stick the transparent tape which covers the components. At the top of the organizer there is a notch for paper, used for components labels. Most SMD components are packed in 8mm wide tapes, making the optimal compartment width 10mm. It is not easy to cut the 10mm thick acrylic and get a neat edge – instead, you could use more layers of thin sheets to make the spacers. Using 5mm acrylic you can combine more layers for any width of tape, which contains wider components, like SMD integrated circuits. The only thing that you have to be careful about, is to keep the distance between the thin steel rod and acrylic, which is marked as “2-4mm” on the drawing. It is good if this space is just a few tenths of a millimeter wider than the thickness of SMD tapes.

smd_orthoThe CorelDraw file that can be used for laser cutting the acrylic parts, is available for download. If you scale the profiles, don’t forget to readjust the hole diameters and some other dimensions which have to remain intact. If you have 5mm acrylic pieces, you should probably use two layers of acrylic for every tape (red parts on the drawing). The barrier layers would be made of thin acrylic — for instance 2mm (the blue parts). Edge layers (green) are once again 5mm thick, and there are also the end pieces (yellow), glued to the previous borders and used to “round up” the whole construction and to protect your hands from the threaded rods and nuts.

While you’re building this for your bench, make a vacuum picking tool for SMDs out of a dispensing syringe with a thick needle. It’s a common trick for hackers to use an aquarium air pump, just turn the compressor unit by 180°, so that it creates vacuum instead of blowing the air outside. This process is described by R&TPreppers in the video below.

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Pack Your Plywood Cuts with Genetic Algortihms

Reading (or writing!) Hackaday, we find that people are often solving problems for us that we didn’t even know that we had. Take [Jack Qiao]’s SVGnest for instance. If you’ve ever used a laser cutter, for instance, you’ve probably thought for a second or two about how to best pack the objects into a sheet, given it your best shot, and then moved on. But if you had a lot of parts, and their shapes were irregular, and you wanted to minimize materials cost, you’d think up something better.

SVGnest, which runs in a browser, takes a bunch of SVG shapes and a bounding box as an input, and then tries to pack them all as well as possible. Actually optimizing the placement is a computationally expensive proposition, and that’s considering the placement order to be fixed and allowing only 90 degree rotations of each piece.

Once you consider all the possible orders in which you place the pieces, it becomes ridiculously computationally expensive, so SVGnest cheats and uses a genetic algorithm, which essentially swaps a few pieces and tests for an improvement many, many times over. Doing this randomly would be silly, so the routine packs the biggest pieces first, and then back-fills the small ones wherever they fit, possibly moving the big ones around to accommodate.

That’s a lot of computational work, but the end result is amazing. SVGnest packs shapes better than we could ever hope to, and as well as some commercial nesting software. Kudos. And now that the software is written, as soon as you stumble upon this problem yourself, you have a means to get to the solution. Thanks [Jack]!

Laser Cut-and-Weld Makes 3D Objects

Everybody likes 3D printing, right? But it’s slow compared to 2D laser cutting. If only there were a way to combine multiple 2D slices into a 3D model. OK, we know that you’re already doing it by hand with glue and/or joints. But where’s the fun in that?

LaserStacker automates the whole procedure for you. They’ve tweaked their laser cutter settings to allow not just cutting but also welding of acrylic. This lets them build up 3D objects out of acrylic slices with no human intervention by first making a cutting pass at one depth and then selectively re-welding together at another. And they’ve also built up some software, along with a library of functional elements, that makes designing these sort of parts easier.

There’s hardly any detail on their website about how it works, so you’ll have to watch the video below the break and make some educated guesses. It looks like they raise the cutter head upwards to make the welding passes, probably spreading the beam out a bit. Do they also run it at lower power, or slower? We demand details!

Anyway, check out the demo video at 3:30 where they run through the slice-to-depth and heal modes through their paces. It’s pretty impressive.

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Laser-cut Cardboard Planetary Gearset is Pretty, but Useless

[Shane] made a project that speaks directly to our heart — combining laser cutting, cardboard, and gears. How could it be any better? Well, it could do anything. But that’s quibbling. It’s fun enough just to watch the laser-cut cardboard planetary gears turn. (Video after the break.)

It was made on a laser cutter using the gear extensions for generating gears in Inkscape, everybody’s favorite free SVG editor.

In his writeup, [Shane] touches on all of the relevant details: all of the gear pitches need to be the same, and the number of teeth in the sun gear (in the center) needs to equal the number of teeth in the ring (outside) divided by the number of planets (orbiting, in the middle). So far so good.

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Full-Color Edge-Lit Laser Cut Acrylic

Edge-lit art has been around for a very long time, and most people have probably come across it in a gift shop somewhere. All it takes is a pane of transparent material (usually an acrylic sheet) with the artwork etched into the surface. Shine a light into the sheet from the edge, and refraction takes over to light up the artwork. However, this technique is almost always limited to a single pane, and therefore a single color. [haqnmaq] wanted to take this idea and make it full-color, and has written up a great Instructables tutorial on how to accomplish this.

If you want to make something like this yourself, the only thing you really need is a laser cutter and some basic electronics equipment. The process itself is so straightforward that it’s surprising that it isn’t more common. You start by taking a photo of your choice and use an image editor to break it up into three photos, one for red, one for green, and one for blue. Each of those photos is then etched into an acrylic pane with a laser cutter. When the panes are positioned in front of each other and edge-lit with their respective LEDs, a full-color image comes to life.

This isn’t the first edge-lit artwork project we’ve featured, but it definitely has the highest fidelity. Because [haqnmaq’s] technique uses three colors, you can use his tutorial to reproduce any photo you like. You could even take this a step further and create animated photos by adding more panes and lighting them up in the correct sequence!

Wii-Motified Laser Cutter refocuses for Contoured Cutting

Still laser cutting all of your parts in 2D? Not the folks over at [Just Add Sharks]. With a few lines of code and an in-tact Wii-Mote, they’ve managed to rig their laser cutter to dynamically refocus based on the height of the material.

The hack is cleanly executed by placing the Wii-Mote both at a known fixed distance-and-angle and within line-of-sight of the focused beam. Thankfully, the image-processing is already done onboard by the Wii-Mote’s image sensor, which simply returns the (x,y) coordinates of the four brightest IR points in view. As the beam moves over the material, the dot moves up or down in the camera’s field-of-view, triggering a refocus of the laser as it cuts. Given that the z-axis table needs to readjust with the contour, the folks at [Just Add Sharks] have slowed down the cutting speed. Finally, it’s worth noting that the Wii-Mote was designed to detect IR LEDs, not a 10600-nanometer laser beam, but we suspect that the Wii-Mote is receiving colors produced by the fluorescing material itself, not the beam. Nevertheless, the result is exactly the same–a dynamically refocusing laser!

Now that [Glowforge] has released a continuously-refocusing laser cutter implemented with stereoscopic cameras, it’s great to see the community following in their footsteps with a DIY endeavor. See the whole system in action after the break!

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