Up Your CAD Game With Good Reference Photos

May 6, 2016 by Gerrit Coetzee 28 Comments

I’ve taken lots of reference photos for various projects. The first time, I remember suffering a lot and having to redo a model a few times before I got a picture that worked. Just like measuring parts badly, refining your reference photo skills will save you a lot of time and effort when trying to reproduce objects in CAD. Once you have a model of an object, it’s easy to design mating parts, to reproduce the original, or even for milling the original for precise alterations.

I’m adding some parts onto a cheap food dehydrator from the local import store. I’m not certain if my project will succeed, but it’s a good project to talk about taking reference photos. The object is white, indistinct, and awkward, which makes it a difficult object to take a good photo for reference use in a CAD program. I looked around for a decent tutorial on the subject, and only found one. Maybe my Google-fu wasn’t the best that day. Either way, It was mostly for taking good orthogonal shots, and not how to optimize the picture to get dimensions out of it later.

There are a few things to note when taking a reference photo. The first is the distortion and the setup of your equipment to combat it. The second is including reference scales and surfaces to assist in producing a final model from which geometry and dimensions can be accurately taken. The last is post-processing the picture to try to fight the distortion, and also to prepare it for use in cad and modeling software.

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3D Printing Hailstone Molds For Science

May 6, 2016 by Kristina Panos 8 Comments

Hollywood would have you believe that tornadoes are prevalent in the Midwest. We’re much more likely to see hail in the springtime—balls of slushy ice that pelt our roofs and dimple our cars. [Dr. Ian Giammanco] and his wife and fellow scientist [Tanya Brown-Giammanco] have been studying hail at the Insurance Institute for Business and Home Safety’s research lab since 2012. In 2013, their team created over 9,000 artificial hailstones and fired them at a mock-up of a house in the first indoor full-scale hailstorm.

As fun as it sounds to shoot balls of ice at different things, they did it to better understand the humble hailstone and the damage it can do to insurable goods. Those hailstones from a few years ago were created manually by injecting molds and freezing them. Recently, [the Giammancos] and have taken a more advanced approach to creating artificial hail so they can study the physical characteristics. They scan actual hailstones in order to create models of them. Then they make a 3D-printed mold and use it in a hail-making machine that uses diffused carbon dioxide to mimic the layering that occurs when natural hailstones are formed.

While it would be nice to be able to control hail, the next best thing is mitigating the damage it causes. The better that scientists understand hail, the better materials will become that can withstand its impact. Perhaps someone can perfect a shape-shifting building material and make it resistant to hail.

Fail Of The Week: ESP8266 Heats Temperature Sensor

May 6, 2016 by Elliot Williams 61 Comments

[Richard Hawthorn] sent us in this interesting fail, complete with an attempted (and yet failed) clever solution. We love learning through other people’s mistakes, so we’re passing it on to you.

First the obvious-in-retrospect fail. [Richard] built a board with a temperature sensor and an ESP8266 module to report the temperature to the Interwebs. If you’ve ever put your finger on an ESP8266 module when it’s really working, you’ll know what went wrong here: the ESP8266 heated up the board and gave a high reading on the temperature sensor.

Next came the clever bit. [Richard] put cutouts into the board to hopefully stop the flow of heat from the ESP8266 module to the temperature sensor. Again, he found that the board heats up by around four degrees Celcius or nine degrees Farenheit. That’s a horrible result in any units.

What to do? [Richard’s] first ideas are to keep hammering on the thermal isolation, by maybe redoing the board again or adding a heatsink. Maybe a daughterboard for the thermal sensor? We can’t see the board design in enough detail, but we suspect that a flood ground plane may be partly to blame. Try running thin traces only to the temperature section?

[Richard]’s third suggestion is to put the ESP into sleep mode between updates to reduce waste heat and power consumption. He should be doing this anyway, in our opinion, and if it prevents scrapping the boards, so much the better. “Fix it in software!” is the hardware guy’s motto.

But we’ll put the question to you ~~electronics-design backseat drivers~~ loyal Hackaday readers. Have you ever noticed this effect with board-mounted temperature sensors? How did you / would you get around it?

Fail of the Week is a Hackaday column which celebrates failure as a learning tool. Help keep the fun rolling by writing about your own failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.