Electronifying A Horror Fraught Hydraulic Press

April 18, 2017 by Brian Benchoff 38 Comments

[Josh] is replacing the springs in his car’s suspension. He wanted to know the travel rates of these springs, but apparently, this is a closely guarded trade secret in the industry. One company did manage to publish the spring rates, but they weren’t believable. Instead of taking this company’s word, [Josh] built a spring tester.

The theory behind a spring tester is pretty simple: apply a force to a spring, measure it, then measure how much the spring has traveled. Or compress a spring an inch or so, measure the force, and compress it some more. Either gets you the same data.

This spring tester is built around a Harbor Freight hydraulic press. Yes, the spring is completely captured and won’t fly out of the jig if you look at it wrong. The bottom of the press contains a few load cells, fed into an ATmega8, which displays a value on an LCD. For the displacement measurement, a ruler taped to the side of the press will suffice, but [Josh] used a Mitutoyo linear scale.

What were the results of these tests? You shouldn’t buy coils from Bilstein if these results are correct. The rates for these springs were off by 70%. Other springs fared better and won’t bind when going over bigger bumps. That’s great work, and an excellent application of Horror Fraught gear.

The Surface Area To Volume Ratio Or Why Elephants Have Big Ears

April 18, 2017 by Manuel Rodriguez-Achach 48 Comments

There are very few things that are so far reaching across many different disciplines, ranging from biology to engineering, as is the relation of the surface area to the volume of a body. This is not a law, as Newton’s second one, or a theory as Darwin’s evolution theory. But it has consequences in a diverse set of situations. It explains why cells are the size they are, why some animals have a strange morphology, why flour explodes while wheat grains don’t and many other phenomena that we will explore in this article.

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Making Tension Based Furniture

April 18, 2017 by Michael Uttmark 21 Comments

[Robby Cuthbert,] an artist and designer based out of Fort Collins, Colorado is creating stable cable tables that are simultaneously a feat of engineering and a work of art.

[Cuthbert’s] tables are held together by 1/16″ stainless steel cables that exert oppositional tensions that result in a structurally stable and visually appealing coffee table. In his video, [Cuthbert] leads us through his process for creating his tables, step by step. [Cuthbert] starts by cutting out bamboo legs on his CNC mill. He then drills holes in each leg for cables and mounts each leg on his custom table jig. Then, he attaches the stainless steel cabling taking care to alternate tension direction. The cables are threaded through holes in the legs and affixed with copper crimps. After many cables, he has a mechanical structure that can support his weight that also looks fantastic. All in all, [Cuthbert’s] art is a wonderful example of the intersection of art and engineering.

If we’ve whet your appetite, fear not, we have featured many tension based art/engineering hacks before. You might be interested in these computer-designed portraits or, if the thought of knitting by hand gives you the heebie-jeebies, the Autograph, a string art printer might be more your style.

Video after the break.

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Brazil Wins The Raspberry Pi Overclocking Olympics

April 18, 2017 by Adil Malik 20 Comments

[Alex Rissato] proudly reports that he now holds the record for highest benchmark score on HWBOT (machine translation); something he sees not only as a personal achievement but admirably, of national pride. Overclocking a Raspberry Pi is not as simple as achieving the highest operational clock rate. A record constitutes just the right combination of CPU clock, memory clock, GPU clock and finally the CPU core voltage. If you’ve managed to produce that special sauce, the combination must be satisfactorily cooled and most importantly be stable enough to pass an actual performance benchmark.

[Alex] realized that the main hurdle to achieving the desired CPU clock was the internally generated and hence restricted, CPU core voltage; This is externally LC filtered and routed back to the CPU on a stock Pi. [Alex] de-soldered the filter on the PCB and provided the CPU with an externally generated core voltage.

Next, the cooling had to be tended to. Air cooling simply wouldn’t cut it, so a Peltier based heatsink interface had to be devised with the hot side immersed in a bucket of salt water. All of this translated to a comfy 16C at a clock speed of 1600 MHz.

Was all the effort justified? We certainly think it was! Despite falling short of the Pi zero CPU clock rate record, currently set at 1620MHz, [Alex] earned the top spot in the HWBOT Prime overclocking benchmark. Brazil can now certainly add this to its trophy cabinet, arguably overshadowing the 129 Olympic medals.