Laser Cut Miter Joints

polyhedraEvery project deserves its own laser cut enclosure, of course, but the most common method of joinery – an overabundance of mortises and tenons, and if you’re lucky, a bit of kerf bending – is a little unsightly. Until tastes in industrial design change to accommodate this simple but primitive method of joining two laser cut panels together at an angle takes hold, the search will continue for a better way to cut acrylic and plywood on a laser cutter. The folks at Just Add Sharks might have a solution to this problem, though: miter joints with a laser cutter.

Instead of the slots and tabs of the usual method of constructing laser cut enclosures, miter joints produce a nearly seamless method of joining two perpendicular panels. The key, of course, is cutting a 45° bevel at the joint and gluing or fastening the pieces together. Just Add Sharks is doing this with a laser cut jig that holds a plywood or acrylic piece at a 45° angle to the laser beam. Yes, it’s only one cut per pass, but after adjusting the depth of cut to 1.4 times the thickness of the material, miter joints are easy.

Using a laser for miter joints isn’t limited to 45°, either. There are a few examples of an octahedron and icosahedron. Of course fastening these mitered panels together will be a challenge, but that’s what clamps and glue are for.

Better Lasing With Pulses

laser

The folks at the Lansing, Michigan hackerspace built themselves a 40 Watt laser cutter. It’s an awesome machine capable of cutting plywood and acrylic, and is even powered by a RAMPS board, something normally found in 3D printers. They wanted a little more power out of their 40 Watt tube, though, and found pulsing the laser was the best way to do that.

Unlike the fancy Epilog and Full Spectrum Laser machines, the Buildlog.net 2.x laser cutter found in the Lansing Hackerspace didn’t use Pulse-Per-Inch (PPI) control until very recently. When a laser tube is turned on, the output power of the laser is much higher – nearly double the set value – for a few milliseconds. By pulsing the laser in 2-3 ms bursts, it’s possible to have a higher effective output from a laser, and has the nice added benefit of keeping the laser cooler. The only problem, then, is figuring out how to pulse the laser as a function of the distance traveled.

To do this, the laser cutter must accurately know the position of the laser head at all times. This could be done with encoders, which would require a new solution for each controller board. Since laser cutters are usually driven by stepper motors controlled with step and direction signals, a much better solution would be to count these signals coming from the CNC computer before it goes to the RAMPS driver, and turn the laser on and off as it moves around the bed.

A few tests were done using various PPI settings, each one inch long, shown in the pic above. At 200 PPI, the laser creates a continuous line, and at higher PPI settings, the lines are smoother, but get progressively wider. The difference between PPI settings and having the laser constantly on is subtle, but it’s there; it’s not quite the difference between an axe and a scalpel, but it is a bit like the difference between a scalpel and a steak knife.

It’s an impressive build for sure, and something that brings what is essentially a homebrew laser cutter a lot closer to the quality of cutters costing thousands of dollars. Awesome work.

 

Customized iPad LCD Screen Clips onto Macbook as a Slick Second Screen

Macbook with iPad second screen

Last year, [Ben] found a good deal on iPad 3 LCD screens. He couldn’t resist buying a couple to play around with. It didn’t take him long to figure out that it’s actually quite simple to use these LCD screens with any computer. This is because the LCD panels have built-in Apple Display port interfaces. This means that you can add your own Display Port connector to the end of the LCD’s ribbon connector and just plug it into a computer. You’ll also need to hook up a back light driver, which [Ben] was able to find pre-made for around $35.

The hack doesn’t stop there, though. [Ben] wanted to have a nice, finished product. He laser cut an acrylic bezel for the LCD screen that was a perfect fit. He then milled out a space for the LCD to fit into. The acrylic was thick enough to accommodate the screen and all of the cables. To cover up the back, [Ben] chose to use the side panel of a PowerMac G5 computer case. He chose this mainly for aesthetics. He just couldn’t resist the nice brushed aluminum look with the giant Apple logo. It would be a perfect match to his Macbook.

Once the LCD panel was looking nice, [Ben] still needed a way to securely fasten it in the right place. He knew he’d want it next to his Macbook, so why not attach it directly to the Macbook? [Ben] got to work with his 3D printer and printed up some small plastic clips. The clips are glued to the iPad screen’s acrylic bezel and can be easily clipped on and off of the Macbook screen in seconds. This way his laptop is still portable, but he has the extra screen real estate when he needs it. [Ben] also printed up a plastic clip that turns the iPad’s USB power connector and the Display Port connector into one single connector. While this is obviously not required, it does effectively turn two separate plugs into one and makes the whole project that much more slick.

The Laser Cutter Attachment For A 3D Printer

cheapo If you already have a 3D printer, you already have a machine that will trace out gears, cogs, and enclosures over an XY plane. How about strapping a laser to your extruder and turning your printer into a laser cutter? That’s what [Spiritplumber] did, and he’s actually cutting 3/16″ wood and 1/4″ acrylic with his 3D printer.

[Spiritplumber] is using a 445nm laser diode attached directly to his extruder mount to turn his 3D printer into a laser cutter. The great thing about putting a laser diode on an extruder is that no additional power supplies are needed; after installing a few connectors near the hot end, [Spiritplumber] is able to switch from extruding to lasing by just swapping a few wires. The software isn’t a problem either: it’s all just Gcode and DXFs, anyway.

There’s an Indiegogo for this, with the laser available for $200. Compare that to the Chinese laser cutters on eBay, and you can see why this is called the L-CHEAPO laser cutter.

A Huge, Lightweight Wooden Quadrotor

quad_1

[Robert] once built a quadcopter frame by sawing laminate floor tile. It worked, we’re taking the lack of pictures of this build as evidence of how ugly it was. His latest design used a much better looking material – laser cut plywood – and the finished product is very strong and lightweight, even compared to commercial frames made with glass or carbon fiber and epoxy.

Although the design went smoothly thanks to some Solidworks skills, actually cutting the frame from 3mm birch ply resulted in a few issues. The cheap laser cutter used for cutting include some bottom of the line software called LaserWorksV5. There is a kerf compensation feature, called ‘sew compensation’ in the software’s native Chinglish. The software would always crash whenever it tried to calculate the compensation for circles. [Robert] spent two hours figuring this problem out, and in the end needed to break out a piece of sand paper to get a nice interlocking fit.

The completed frame bolts together without any glue at all, and the best part about it is the weight – only 167 grams. Compare that to a similarly sized glass fiber frame, and [Robert]’s shaved at least 200 grams off his finished build.

Ikea Desk Laser Cutter Combo

Abandoned DIY Laser Cutter installed in Ikea Desk

Craigslist can be a good source for finding someone else’s abandoned projects. Besides being extremely jealous, you’ll agree that [Mike’s] find is atypical of the normal Craigslist listings. He scored a 75% complete group of laser cutter parts for $500. That included the XY frame, stepper motors, Gecko motor drivers, optics, and 40 watt CO2 laser tube. He paired the laser parts with another Craigslist find, a $15 desk. A few more parts and 3 weeks of tinkering later, [Mike] had a working DIY mutant Ikea Desk Laser Cutter.

The laser cutter has a 23 x 14 inch work envelope and is controlled via Mach3. The X Axis of the frame had a little bit of wobble in it so [Mike] added a THK linear rail and bearing to stiffen it up. To add a little bit of mistake proofing to the laser, [Mike] put a water flow sensor in the laser tube cooling system. The laser will not turn on unless water is pumping to cool the laser tube. Wrecking your laser tube by accident would be a total bummer!

Continue reading “Ikea Desk Laser Cutter Combo”

Augmented Laser Cutter Removes Design Technology Barriers

augmented laser

Laser cutters, 3D printers, CNC routers — they’re all great technology in the right hands, but unfortunately the learning curve sometimes puts would-be makers at a distance.  [Anirudh] from MIT’s Media Lab is attempting to break down at least one of those barriers with his augmented laser cutter system called, Clearcut.

The system consists of a webcam, a projector, and a semi transparent work space on top of the laser cutter. By placing objects on the surface, the webcam can identify them, duplicate them with the projector, and then laser engrave them. In addition to the “copy and paste” idea of this, you can also use infrared emitting pens to physically draw your design on the work surface to be engraved. It starts to bridge the gap between complex CAD and pencil and paper, something anyone is capable of.

Continue reading “Augmented Laser Cutter Removes Design Technology Barriers”