More Acetone-vapor Polishing Experiments

March 2, 2013 by Mike Szczys 42 Comments

acetone-vapor-polishing-experiments

If you’re thinking of trying the acetone-vapor polishing process to smooth your 3D printed objects you simply must check out [Christopher’s] experiments with the process. He found out about the process from our feature a few days ago and decided to perform a series of experiments on different printed models.

The results were mixed. He performed the process in much the same way as the original offering. The skull seen above does a nice job of demonstrating what can be achieved with the process. There is a smooth glossy finish and [Christopher] thinks there is no loss of detail. But one of the three models he tested wasn’t really affected by the vapor. He thinks it became a bit shinier, but not nearly as much as the skull even after sending it through the process twice. We’d love to hear some discussion as to why.

There is about eight minutes of video to go along with the project post. You’ll find it after the jump.

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Soluble Support Structure Can Be Used With Any Extruder-based 3D Printer

March 1, 2013 by Mike Szczys 34 Comments

One of the issues with extruder-based 3D printing is that it can be very difficult to print objects that have voids in them. You simply must have something to deposit the soft material on until it has a chance to harden. [Matt] found a solution which should work for any extruder-based printer (with one caveat we’ll get to in a minute). He prints a support structure out of HIPS then later dissolves it using Limonene. The image on the left shows the object soaking for 24 hours. The final project is seen beside it.

The only real problem with this technique is that it requires a second extruder. Since printers build objects by layers, switching material in a single print head isn’t an option. HIPS stands for High-Impact Polystyrene. It extrudes at the same temperature as the ABS (235C) and adheres well to a heated bed kept at 115C. ABS will be unaffected by the hydrocarbon solvent Limonene, except for the residual smell of citrus.

Automated PH Control

February 23, 2013 by Eric Evenchick 25 Comments

Controlling the pH level of a solution is usually a tedious task. Adding an acid or base to the solution will change the pH, but manually monitoring the levels and adding the correct amount isn’t fun. [Reza] rigged up an automated pH controller to keep a solution’s pH steady.

The build uses an Arduino with a LCD shield, screw terminal shields, and [Reza]’s own pH shield attached. A peristaltic pump is used to pump the pH down acid into the solution. This type of pump isolates the fluid from the pump parts, preventing contamination of the solution. The pump is controlled using a PowerSwitch Tail, allowing the Arduino to control the flow of fluid.

An Omega pH probe is used to read the pH level. [Reza]’s open source firmware has support for calibrating the probe to ensure accurate readings. Once it’s set up, the screen displays the pH level and the current state of the system. The pump is enabled when the pH rises out of the desired range.

After the break, check out a video walk through of the device.

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Building A Tool To Measure Melting Point

February 8, 2013 by Mike Szczys 5 Comments

melting-point-apparatus

When working with chemical reactions it may be necessary to test the purity of the components you’re using. This is especially true with hobby chemists as they often acquire their raw materials from the hardware store, garden center, or pool supply. [Ken] figured out how to get around the $500 price tag of a commercial unit by building this DIY melting point test apparatus.

In this image he’s using a thermocouple to monitor the temperature of the melting surface, but mentions that you can do this with an inexpensive dial thermometer and will still have great results. That melting surface is the hexagonal head of a bolt which he drilled out to provide a concave surface for the test compound. Inside the PVC pipe is the heating element from a 40W hot glue gun. He wrapped it in fiberglass fabric which is sold in the plumbing supply to protect the area around pipe joints during soldering. The rotary light dimmer feeds the electricity to the element, allowing for adjustments to the ramping speed.

Making High Concentrations Of Hydrogen Peroxide At Home

February 3, 2013 by Brian Benchoff 88 Comments

Hydrogen peroxide – the same stuff you can pick up from a drug store or beauty supply store – is one of those very interesting chemicals that belongs on every maker’s cabinet. At concentrations of about 30%, it’s perfect for etching PCB boards, and at even higher concentrations – about 70% – it can be used as rocket fuel. Unfortunately for the home hacker, it’s very difficult and expensive to obtain peroxide in concentrations above 3% or so. That’s alright with [Charlie], though, because he’s come up with a way to concentrate peroxide and measure the concentration once he’s done.

There are a few YouTube videos of kitchen chemists concentrating peroxide by heating it on a stove to just under 100°C. Because hydrogen peroxide boils at 150°C, they’re simply boiling off the water and increasing the concentration of peroxide. This is a qualitative method, and you’ll never know what concentration you’re getting. [Charlie] rigged up a small-scale with a pipette to measure the weight of his concentrated peroxide per unit of volume, giving him the density of his concoction and thus the concentration.

We have to note that concentrated peroxide is dangerous stuff, but the results of [Charlie]’s lab work aren’t much more dangerous than what hair stylists work with every day. If you’re going for high-test peroxide, good job, that’s awesome, but do be aware of the risks.

Mr. Tea Is A Hot Plate And Magnetic Stirrer In The Same Enclosure

January 30, 2013 by Mike Szczys 17 Comments

mr-tea-stir-and-hot-plate

Not being a coffee drinker [Hunter Scott] wanted a way to make tea while lurking in his workshop. Well it’s not exactly rocket science, as all you need is water at the right temperature and a vessel in which the tea can be steeped. But we do commend him on not only building a nice little hot plate enclosure, but rolling a magnetic stirrer into the other side of the box.

You heard us right, the stirrer is not combined with the plate, but resides on the underside of the same PSU enclosure. The plate itself is from a unit he bought at the store and cannibalized. The light switch dimmer lets him adjust the heat it puts out. When not hot, he can flip it over and use the stir plate. This consists of a hard drive magnet attached to a PC fan. For the stirrer itself he encased a neodymium magnet in some thermoplastic. The magnetic combination works well together with a demonstration which shows it stirring water through the base of a tea-cup.

An Arduino Hydrogen Blimp… Oh The Humanity!

January 19, 2013 by Mike Szczys 48 Comments

arduino-hydrogen-balloon

This sort of flying contraption seems more suited for indoor use. Well, except for the fire hazard presented by building an Android controlled hydrogen blimp. The problems we often see with quadcopters come into play when a motor wire comes loose and the thing goes flying off in a random direction. Loosing a motor on this airship will be no big deal by comparison.

Because the build relies on the buoyancy of the gas, light-weight components are the name of the game. The frame of the chassis is built from balsa wood. It supports two tiny DC motors which are almost indistinguishable in the image above. An Arduino nano and wireless receiver monitor commands from the transmitter and drive the propellers accordingly.

You may have noticed that we categorized this one as a chemistry hack. That’s because [Btimar] generated the hydrogen himself. He used an Erlenmeyer flask with a spout for the chemical reaction. After placing several heat sinks and other scraps of solid aluminum in the flask he poured on the lye solution. This generates the H2 but you need to keep things cool using ice to keep the reaction from getting out of control. We’re going to stick with helium filled blimps for the time being!

See this beast flying around [Btimar’s] living room in the clip after the break.

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