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Member Since: May 20, 2008

Country: United States


After 20 years in embedded software and hardware engineering and management, finally went back to school and finished my last 40 credits to get a BS in Computer Science from Colorado Technical University, class of 2007.

Was an EE in the 1980's then embedded software engineer, then engineering management in software/hardware/systems - phone and cell data communications and power management. Now disabled and unable to work.

I have a wide variety of interests. These include radio control planes, heli and multicopters, valve (tube) based electronics, autonomous robotics, 4 legged locomotion, Internet Of Things, photography and video production, alternative energy and power conversion, and climate science.

  • My dad used to say that the best way to lose your shirt is to go into a business that you don't understand. I think Galileo is a perfect example of that.

  • I can't see why that wouldn't work, but many of the newer hot ends do not use PTFE because it is limited to temperatures under approximately 235C. If you want to print the higher temperature materials like some of the nylons, and certainly polycarbonate, you don't want any plastic in your hot end. That's the basis for hot ends like the Magma and Hexagon hot end, neither of which contain any plastic.

  • If you go to the LulzBot site they do not specify what materials can be printed with the Flexystruder. In the installation instructions, at the end they do say "now insert your favorite flexible filament." If I were going to buy one of these I would probably call them and ask them first.

  • Unlike PLA or ABS, Ninjaflex is very soft so it is not capable of supporting itself under compression if unsupported. The extruder needs to contain the filament immediately after the driving element (i.e., bearing on knurled shaft) all the way to the heated nozzle. Some print heads are designed with a significant open gap and while this is not a problem with stiffer materials, it is a showstopper for Ninjaflex. This is also why extruders that use Bowden tubes to separate the filament driver from the hot end do not work well with this material. It's so soft it binds in the tube. The Flexystruder is designed to accept the limitations of this new material. Another advantage of this tool head is that it is free of polymer parts so it can handle very high temperatures. I would guess it is capable of 260C or more. However, all-metal extruders like this tend to allow the filament to soften or melt before it gets to the nozzle which causes jamming. The only way to stop this is to keep the upper part of the hot end cool. The fins help, but a variable speed fan is a better solution to allow different materials and feed rates. Though fans have their problems as well - differential air temperature in the build volume. and difficulty in getting the build platform to stay hot due to air flowing over the glass.

  • I've been involved with Linux as a user/developer/embedded engineer since the 90's but I still find the Pi a fascinating bit of tech since it's so cheap you can do things with it that previously would not have made economic sense. I picked up a copy of this book for a young friend of the family who was looking for something the help him get past the newbie stage, and while I did not read the book in detail I took a close look at the TOC and read a few of the example projects.

    This book covers configuration tasks not obvious to someone starting out, like setting up SSH, configuring a static IPv4 address, configuring the Pi to run headless, etc. Of course you can find this information online - you can find almost everything online - but the information is presented here in a cohesive way and at a high level of quality. Most important it avoids the need to search through piles of howto articles to find what you need. It also solves the "where do I start" problem that plagues many people transitioning from linux users to linux hackers ("hackers" in the context of the book). The project ideas are numerous and cover a pretty wide range, and can be easily modified for other uses.

    At 400 printed pages and $20 I think the book provides a good value for its intended audience. That is, those that have got past the shiny-new-toy stage, but who are not comfortable modifying config files or driving I/O without some guidance.

    Disclaimer: I have no professional relationship with Sparkfun, the book's publishers, or anyone else relevant to this post. I just liked the book. YMMV.

  • More than 20 years ago Microchip published an I/O app guide, a little 3x5in. sized printed pamphlet (remember those?) that was included with the development boards. Most of Microchip's business was low pin count parts back then, so I/O was at a premium. This guide showed how to get more bang from each I/O - using one I/O to drive 2 LEDs, PWM for DAC output, etc. This is very similar to one of those app note circuits except as I remember that one used a simple voltage divider rather than a current source. Funny how nothing ever really changes.

  • The BMP180 can trade off power and response time for accuracy via its different modes essentially by oversampling. And as @BradLevy said, accuracy is not the same as resolution. But for many applications you would be more interested in resolution and relative accuracy (ie, after self-calibration) than absolute accuracy. Altitude hold on a multicopter is one example.

    You can get close to 0.25m relative accuracy (noise) for altitude hold and low altitude altimeter applications with this device, though if you're trying to use it as a barometer for absolute pressure its at least an order of magnitude less accurate.

    Also: you can't use this for high altitude rocketry or near space balloon applications as it is only specified to 9000m ASL.

  • There is a Rev 2 of this board now available that has the Wifi module onboard rather than as a USB dongle. It seems to be identical otherwise as it runs the same OS code. I would guess they just mapped the onboard Wifi so it appears to be USB connected but if anyone knows for sure please comment.

    Does anyone know if SF is going to sell these, and if so, when? They are only a few dollars more than the Rev 1 version and appear to be available now on competitive websites.

  • Pull too hard, break connector. Don't pull hard, connector lasts for months like mine. Physics is a bit*h

No public wish lists :(