How To Nail A Technical Presentation

December 29, 2016 by Zoe Skyforest 49 Comments

Whether you’re an engineer, a maker, a hacker or a baker, at some point you’ll want to share your work with other people. Perhaps it’s a meeting at work to discuss process improvements, or a talk at a conference discussing some research you’ve done into hacking a new embedded platform. Or maybe you’ve developed a brand new cooking profile for rye breads that cuts energy usage in half. Whatever it is, there are techniques you can use to help you communicate effectively to a room full of people, and have fun doing it. Unlike some, I actually enjoy getting up in front of a crowd to present my work, so I’ve written this article to share with you some tips that can help you make a technical presentation that everyone will love — including you!

Editor’s Note: We planned the art for this article before the passing of Carrie Fisher. Leia certainly knew how to give a compelling technical presentation. We publish this in memory of a great actress.

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In Defense Of The Electric Chainsaw

December 28, 2016 by Jenny List 94 Comments

Here at Hackaday we are a diverse bunch, we all bring our own experience to the task of bringing you the best of the hardware scene. Our differing backgrounds were recently highlighted by a piece from my colleague [Dan] in which he covered the teardown of a cordless electric chainsaw.

It was his line “Now, we’d normally shy away from any electric chainsaw, especially a cordless saw, and doubly so a Harbor Freight special“. that caught my eye. I’m with him on cordless tools which I see as a cynical ploy from manufacturers to ensure 5-yearly replacements, and I agree that cheap tools are a false economy. But electric chainsaws? Here on this small farm, they’re the saw of choice and here’s why.

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Liar’s 3D Printing: Multiple Colors With One Extruder

December 27, 2016 by Al Williams 12 Comments

Good 3D printers now have multiple hot ends. You ought to be able to print in different colors or print support material. However, a lot of us don’t have multiple hot ends. Turns out, you don’t have to have multiple hot ends to print in multiple colors. To accomplish that you need a lot of patience and the willingness to tell bald-faced lies. Don’t worry, though, you’ll only be lying to some computer hardware and software, so that doesn’t count.

You may have seen people talk about putting a pause between layers to switch from one color to another. That works, but it limits your options. For example, if you want to put some colored text on a different colored background, you have to either have the text poke out, or it has to be “under” the background. It can’t be flush if you only have a single extruder and hot end. My method is a lot more trouble, but it can generate good results.

Keep in mind, with hobby-grade printers, multiple color printing has a lot of problems even if you do have multiple extruders. This isn’t a panacea. But you can get results on par with a similar printer that has multiple heads.

Bottom Line Up Front

Here are a few pictures of test prints that use this technique. A Monoprice Mini printer with the stock extruder and hot end created them using different PLA filament. On the left is a test cube, with a color spot in the middle of the layers (as well as some spots on the top surface you can’t see). To the right is a plate with my call sign in a contrasting color. It is hard to tell in the picture, of course, but there is one surface. The text is at the same height as the yellow surface.

I didn’t spend a lot of time making these prints since I was more focused on perfecting the methodology. The layer heights aren’t very fine, the infill is sparse, and the print speed was fast. However, you could invest time into making better-looking prints. You can also use the usual techniques that you use with a “real” multi-extrusion printer (such as priming towers, ooze shields, etc.).

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200 Years Of The Stirling Engine

December 27, 2016 by Manuel Rodriguez-Achach 56 Comments

In the early years of the nineteenth century, steam engines were at work in a variety of practical uses. However, they were still imperfect in many ways. One particular problem were the boilers, that had a tendency to explode, causing injuries and fatalities. Reverend Dr. Robert Stirling, a Scottish clergyman, was concerned about the death toll from exploding boilers. Based on previous work by George Cayley (known for his pioneering work on aeronautics), Stirling filed his patent for a safer engine in 1816. That makes this year the bicentenary of this engine. The Stirling engine has the highest theoretical efficiency of any thermal engine. It is also a relatively simple machine. Unlike other types of engines, there are no valves, and that makes the mechanical design much simpler.

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Ask Hackaday: Computing Square Roots On FPGA?

December 26, 2016 by Elliot Williams 33 Comments

Hackaday reader [nats.fr] wrote in with some code from a project that resizes a video stream on the fly using an FPGA. Doing this right means undoing whatever gamma correction has been applied to the original stream, resizing, and then re-applying the gamma. Making life simpler, [nats.fr] settled on a gamma of two, which means taking a bunch of square roots, which isn’t fast on an FPGA.

[nats]’s algorithm is pretty neat: it uses a first-stage lookup to figure out in which broad range the value lies, and then one step of Hero’s algorithm to refine from there. (We think this is equivalent to saying he does a piecewise linear interpolation, but we’re not 100% sure.) Anyway, it works decently.

Of course, when you start looking into the abyss that is special function calculation, you risk falling in. Wikipedia lists more methods of calculating square roots than we have fingers. One of them, CORDIC, avoids even using multiplication by resorting to clever bitshifts and a lookup table. Our go-to in these type of situations, Chebyshev polynomial approximation, didn’t even make the cut. (Although we suspect it would be a contender in the gamma=1.8 or gamma=2.2 cases, especially if combined with range-reduction in a first stage like [nats.fr] does.)

So what’s the best/fastest approximation for sqrt(x) for 16-bit integers on an FPGA? [nats.fr] is using a Spartan 6, so you can use a multiplier, but division is probably best avoided. What about arbitrary, possibly fractional, roots?

Hackspace U

December 26, 2016 by Jenny List 58 Comments

No Timmy, we're not preparing you for a life of mindless drudgery! PD, via Wikimedia Commons. — No Timmy, we’re not preparing you for a life of mindless drudgery! PD, via Wikimedia Commons.

It’s funny, how obsessed we are with qualifications these days. Kids go to school and are immediately thrust into a relentless machine of tests, league tables, and exams. They are ruthlessly judged on grades, yet both the knowledge and qualifications those grades represent so often boil down to relatively useless pieces of paper. It doesn’t even end for the poor youngsters when they leave school, for we are now in an age in which when on moving on from school a greater number of them than ever before are expected to go to university. They emerge three years later carrying a student debt and a freshly-printed degree certificate, only to find that all this education hasn’t really taught them the stuff they really need to do whatever job they land.

A gold standard of education is revealed as an expensive piece of paper with a networking opportunity if you are lucky. You need it to get the job, but in most cases the job overestimates the requirement for it. When a prospective employer ignores twenty years of industry experience to ask you what class of degree you got twenty years ago you begin to see the farcical nature of the situation.

In our hackspaces, we see plenty of people engaged in this educational treadmill. From high schoolers desperately seeking to learn something other than simply how to regurgitate the textbook, through university students seeking an environment closer to an industrial lab or workshop, to perhaps most interestingly those young people who have eschewed university and gone straight from school into their own startups.

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Creating A PCB In Everything: KiCad, Part 3

December 23, 2016 by Brian Benchoff 19 Comments

This is the third and final installment of a series of posts on how to create a PCB in KiCad, and part of an overarching series where I make the same schematic and board in dozens of different software tools. A few weeks ago, we took a look at making a schematic in KiCad, and more recently turned that schematic into a board ready for fabrication.

For our KiCad tutorials, we’ve already done the basics. We know how to create a PCB, make a part from scratch, and turn that into a board. This is the bare minimum to be considered competent with KiCad, but there’s so much more this amazing tool has to offer.

In part three of this KiCad tutorial, we’re going to take a look at turning our board into Gerbers. This will allow us to send the board off to any fab house. We’re going to take a look at DRC, so we can make sure the board will work once we receive it from the fab. We’re also going to take a look at some of the cooler features KiCad has to offer, including push and shove routing (as best as we can with our very minimalist board) and 3D rendering.

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