CNC Milling Is More Manual Than You Think

November 27, 2017 by Elliot Williams 43 Comments

I was in Pasadena CA for the Hackaday Superconference, and got to spend some quality time at the Supplyframe Design Lab. Resident Engineer Dan Hienzsch said I could have a few hours, and asked me what I wanted to make. The constraints were that it had to be small enough to fit into checked luggage, but had to be cool enough to warrant taking up Dan’s time, with bonus points for me learning some new skills. I have a decent wood shop at home, and while my 3D printer farm isn’t as pro as the Design Lab’s, I know the ropes. This left one obvious choice: something Jolly Wrencher on the industrial Tormach three-axis CNC metal mill.

A CNC mill is an awesome tool, but it’s not an omniscient metal-eating robot that you can just hand a design file to. If you thought that having a CNC mill would turn you into a no-experience-needed metal-cutting monster, you’d be sorely mistaken.

Of course the machine is able to cut arbitrary shapes with a precision that would be extremely demanding if done by hand, but the craft of the operator is no less a factor than with a manual mill in making sure that things don’t go sideways. Dan’s good judgment, experience, and input was needed every step of the way. Honestly, I was surprised by how similar the whole procedure was to manual milling. So if you want to know what it’s like to sit on the shoulder of a serious CNC mill operator, read on!

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Make A Cheap Muon Detector Using Cosmicwatch

November 27, 2017 by Steven Dufresne 13 Comments

A little over a year ago we’d written about a sub $100 muon detector that MIT doctoral candidate [Spencer Axani] and a few others had put together. At the time there was little more than a paper on arxiv.org about it. Now, a few versions later they’ve refined it to the level of a kit with full instructions for making your own under the banner, CosmicWatch including PCB Gerber files for the two surface mount boards you’ll need to assemble.

What’s a muon? The Earth is under constant bombardment from cosmic rays, most of them being nuclei expelled from supernova explosions. As they collide with nuclei in our atmosphere, pions and kaons are produced, and the pions then decay into muons. These muons are similar to electrons, having a +1 or -1 charge, but with 200 times the mass.

This pion-to-muon decay happens higher than 10 km above the Earth’s surface. But the muons have a lifetime at rest of 2.2 μs. This means that the number of muons peak at around 10 km and decrease as you go down. A jetliner at 30,000 feet will encounter far more muons than will someone at the Earth’s surface where there’s one per cm² per minute, and the deeper underground you go the fewer still. This makes them useful for inferring altitude and depth.

Muon detector

How it works

How does CosmicWatch detect these muons? The working components of the detector consist of a plastic scintillator, a silicon photomultiplier (SiPM), a main circuit board which does signal amplification and peak detection among other things, and an Arduino nano.

As a muon passes through the scintillating material, some of its energy is absorbed and re-emitted as photons. Those photons are detected by the silicon photomultiplier (SiPM) which then outputs an electrical signal that is approximately 0.5 μs wide and 10-100 mV. That’s then amplified by a factor of 6. However, the amplified pulse is too brief for the Arduino nano and so it’s stretched out by the peak detector to roughly 100 μs. The Arduino samples the peak detector’s output and calculates the original pulse’s amplitude.

Their webpage has copious details on where to get the parts, the software and how to make it. However, they do assume you can either find a cheap photomultiplier somewhere or buy it in quantities of over 100 brand new, presumably as part of a school program. That bulk purchase makes the difference between a $50 part and one just over $100. But being skilled hackers we’re sure you can find other ways to save costs, and $150 for a muon detector still isn’t too unreasonable.

Detecting muons seems to have become a thing lately. Not too long ago we reported on a Hackaday prize entry for a detector that uses Russian Geiger–Müller Tubes.

Introducing The Mobility Unlimited Challenge

November 27, 2017 by Jenny List 10 Comments

If you take a walk across the centre of your city, you will find it to be a straightforward experience with few inconveniences. The occasional hold-up at a pedestrian crossing perhaps, or maybe a crowd of people in a busy shopping area. If however you take the same walk in the company of a wheelchair user you are likely to encounter an entirely different experience. The streets become a nightmare of obstacles to avoid and inaccessible areas requiring a detour, and suddenly what had been a pleasurable experience becomes a significant effort. Despite building and planning code updates to improve the situation, and millions of dollars invested in ramps, lifts, and other improvements, there remain so many problems to be addressed. Meanwhile legislators and the general public imagine that something has been done, the accessibility box has been ticked, and they can move on to the next thing that captures their attention.

The paralympian athlete [Tatyana McFadden] is an ambassador for the Toyota Mobility Foundation’s Mobility Unlimited Challenge, a global competition with the aim of improving mobility for people with disabilities. She’s written a piece introducing the challenge from her informed point of view as a wheelchair user, and makes the point that the basic design of a chair has not significantly changed since the 1930s. Her sentence: “There may be more hype around Bitcoin, but innovators could have far more impact if they turned their attention to how they can make the freedom to move available to all.” is one to make those of us with an interest in technology stop and think. To introduce the challenge they’ve released a glossy video, and we’ve placed it below the break.

As part of this year’s Hackaday Prize, we had an Assistive Technologies section that attracted some fantastic entries. That demonstrates that our community has plenty of people with the required skills, experience, and ideas to make a difference, and we hope that some of them might be among the entries for the Mobility Unlimited competition. If it excites your interest, we’d like to urge you to give it a second look.

A word of warning though – take care to avoid the Engineer Saviour Trap.

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