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Crafternoon: Forget Potatoes, We’re Making Stamps with Lasers

No, that’s not Heisenberg without his hat. It’s [Jens], and he laser-cut a stamp of his face out of EVA foam. He made the laser cutter himself, which we covered a couple of months ago.

Let’s take a brief interlude to discuss your beautiful eyeballs. Keep them safe, okay? If you’re going to play with lasers, be smart and protect yourself according to the wattage and wavelength. Alright, back to business.

[Jens] started by making a stencil from a photo using this tutorial. He added a frame and supports around his face to keep everything where it should be. [Jens] then turned to Inkscape to generate the g-code using the laser plugin and then proceeded to cut his countenance into EVA foam.

After gluing the foam to a wood backing, he cut off the supports. Now it’s ready to stamp. You could use a brayer if you have one or maybe your wife’s rolling pin to apply whatever ink or paint you want to use. [Jens] loaded up his stamp with a sponge.

Etching designs into denim with a laser cutter

JeansEtchLaser

Finding new uses for your tools and equipment can be very exciting. [Foamy] wrote in to tell us about a blog post by [qbotics] that demonstrates etching designs into denim with a laser cutter. What a cool unexpected use for a laser cutter!

According to the Epilog laser cutter’s website, “we have engraved everything from denim to acrylic with fantastic results”. This inspired the author of “Science with denim” to try engraving jeans. After some experimentation,  [qbotics] found that setting the 75W laser cutter to 15% power at 100% speed worked best. The results are quite impressive; the engraved pattern looks like naturally faded jeans. Amazing.

In the past, we have seen lasers engrave everything from calculators to wood. We would be curious to see if some of the DIY laser cutters could engrave denim as well. Give it a try and tell us about it!

A 3-Axis Paper Cutting Mini Laser

LaserCutter

Laser are awesome, and so are projects that use lasers. A recent Instructable by [kokpat] gives an overview of how to create a fully functional laser paper cutter using CDROM stepper motors and an Arduino.

What is special about this build, is that it showcases how easy it can be to build a 3-axis mechanical system used for laser cutters, CNC machines, and 3D printers. Using a stepper stage that consist of a motor screw with a nut slider based carriage, the mechanical system can be put together quite easily and cost effectively. Luckily, from an electronics and software perspective, everything is quite standardized with the proliferation of the RepRap and similar machines. Simply pick any three stepper drivers, find the most pertinent firmware, and voilà! You’re done! Well, almost. Don’t forget a 100mW violet laser!

We have seen a ton of really cool laser cutters before, but this has to be one of the cheapest. See the laser cutter in action after the break.

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Retrotechtacular: Shedding Light on Holograms

This week’s Retrotechtacular is a 1972 introduction to holography produced by the fine folks at Encyclopædia Britannica. It details quite admirably what holograms are and how they’re made.

Holograms are quite different from photographs, though both are recorded on film. Holography is based on the additive effects of waves: two crests of equal amplitude create a larger crest, while a crest and a trough of equal amplitude cancel each other out, causing an interference effect. The video demonstrates the concept nicely with water ripples and explains that the same effect happens with sound waves and light waves.

Lasers are the key to the intense and spectrally pure light required for holography. Incandescent light consists of too many wavelengths to be effectively split into two identical light wave sources. To create a hologram, a laser is split with an optical device into two beams. One beam is focused directly on the object being recorded and is called the object beam. The second beam is directed away from the scene through a series of mirrors and shone directly onto a film emulsion.

The film records the interference between the waves of the two beams. It appears to be blank after development, but upon close inspection reveals stripes of light and dark. When the exposed film is placed in the path of only the reference beam, the interference patterns recorded on the film split the beam back into two, recreating the scene. With the aid of a screen for projection, the hologram can be seen showing the original object in 2D. Another big difference between photographs and holograms is that even a small portion of a hologram can reproduce the entire scene, but a piece of a photograph is just that.

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Adding a Manual Z-axis To Your Laser

DSC07543 (Custom)

[Martin Raynsford] sells lasers, and laser cuts stuff for a living — we’re kinda jealous. Anyway, laser cutters from China are great, but sometimes lack certain functionality, so he decided to add his own z-axis feature!

The main laser cutter he uses has a very slow z-axis, and it’s also difficult to control — a job can’t be paused to adjust the height offset, the datum must be set every time manually, and you have to be in the very top level of the menu in order to do anything with it! With this in mind, [Martin] decided to add his own z-axis control, completely separate from the laser’s on board control system.

He’s using an Arduino Pro Mini to control the stepper motor with PWM. His new controller has four buttons — fast and slow, in each direction. He’s used the original end stops to protect the axis, and he’s also added a feature to set a datum by holding down both fast and slow buttons at the same time. It ended up being a very cheap upgrade to his system, and he’s also shared the source for anyone looking to recreate it.

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Homebrew Phase Laser Rangefinder

laser

Just when you thought ARM micros couldn’t get any cooler, another project comes along to blow you away. [Ilia] created a phase laser rangefinder (.ru, Google translatitron) using nothing but a laser diode, a pair of magnifying glasses, a few components and an STM32F4 Discovery dev board.

The theory behind this build is using a laser’s phase to determine how far away an object is. By modulating the laser diode’s output at a few hundred Mhz, the reflection from the laser can be compared, giving a fairly reasonable estimate of how far away the target is. This method has a few drawbacks; once the reflection is more than 360 degrees out of phase, the distance ‘loops around’ to being right in front of the detector.

The laser diode used does not have any modulation, of course, but by using an STM32F4 ARM chip, [Ilia]was able to modulate the amplitude of the laser with the help of a driver board hacked out of a 74HC04 chip and a few resistors. Not ideal, but it works.

The receiver for the unit uses a photodiode feeding into the same microcontroller. With an impressive amount of DMA and PLL wizardry (the STM32F4 is really cool, you know), the phase of both the transmission and reflection can be compared, giving a distance measurement.

It’s all an impressive amount of work with a hacked together set of optics, a cheap dev board, and a few components just lying around. For any sort of application in a robot or sensor suite this project would fall apart. As a demonstration of the theory of phase laser rangefinding, though, its top notch.

You can check out a video of [Ilia]‘s rangefinder below. Be sure to full screen it and check out the distance measurement on the LCD. It’s pretty impressive.

Thanks [Володимир] for the link.

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A Cheap Honeycomb Table Replacement for your Laser

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CO2 lasers make use of a honeycomb table which allows you to support parts you are cutting — without cutting into the bed too much. Unfortunately they are a consumable part, so they will eventually wear out, and they aren’t that cheap. [Claptrap] came up with an excellent alternative.

A few months ago, his radiator blew in his station wagon, and it had to be replaced. He was about to throw it out when he realized the similarity of the radiators cooling fins, to that of his honeycomb table… He cut it down to size, pressure washed it (though he notes you should probably wash it first before cutting) and put it in place. It works great!

The only caveat we have is that you should probably flush the radiator with a water pump first — you don’t want to be heating up any residual radiator fluid inside the radiator channels!

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