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December 17 2014
With some inspiration from the potential snow storm last week, I endeavored to test my emergency preparedness for heating my apartment when the power is out. I never did lose power, but the test was successful and I am happy to know that if I did lose power in the winter, I can keep warm at home.
I attached an inverter to a marine battery, then plugged in my Rinnai heater and it ran just fine. The Rinnai does buzz a bit loudly, but that's because the inverter does not produce a "true-sine-wave" signal. I tested the setup with a box-fan attached to the inverter as well and it worked fine.
With the fan and the heater both running on LOW the draw was 115W. Some quick and super dirty math approximations tell me that the battery (if fully charged) will run this about 11 hours. This would be longer if the box-fan isn’t running (less power would be used).
105 Amp hours (sticker value, full charge)
105 Amp hours x 12v = 1260 watt hours (approximate average voltage)
1260 watt hours / 115 watts = ~11 hours
Of course, the inverter can be run from any 12V source. My Honda Civic has an alternator with a faceplate rating of 70Amps. Some quick math tells me how much power this can potentially provide.
70 Amps x 12 Vdc = 840 Wattsdc
I believe the inverter is well within the ability for the alternator to run. So the car could potentially run the inverter as a generator as long as there is gasoline in the tank.
Check out the rest of the info and pictures at my blog.
I november deltok HackBergen i Sparkio Build Night.
Instructables håper vi kan levere 2 instructables av ting vi har laget som involverer Core med Internet Button Shield, og fristen for innlevering er 5 januar 2015.
Så hvis noen av dere har en prosjekt på gang, som bare trenger ferdigstilles – ta kontakt, så gjør vi det sammen!
Hvis vi leverer, så er det mye større sjanse for å få være med i tilsvarende build nights i fremtiden..
December 15 2014
Often laser cut parts gt attached at 90 degree angles, using finger joints, or screws and t-slots, but there may be times when you want to stack pieces of wood and have them aligned…
Pegs might be the answer!
Here’s a few photos of the pegs I’ve been experimenting with. For these pieces I don’t have a lot of room to have multiple pegs at opposing angles, but I can see where that might be useful. For these pieces the peg is really just for assembly alignment when gluing it all together.
December 14 2014
I installed the Y-axis screw drive in MegaMax using the old NEMA-23 stepper motor. A couple really good things came from this:
1) I can now adjust the bed leveling screws from the underside of the bed using thumbwheels instead of a screw driver. I know, I know, everyone else in the world has been able to do this from day 1…
2) Unlike everyone else in the world, with fully supported linear guide rails, the print bed does not move in any direction but along the Y axis. In the old scheme, with the end-supported round guide rails, the rails would flex and the bed would move up and down when applying pressure to it (sometimes even the screw driver pressure to adjust the bed leveling screws). Now, if the bed moves at all in the vertical direction it’s because the bed plate (1/4″ aluminum) itself is flexing!
A couple bad things were also discovered:
1) The vibration and noise problem I was hoping to solve has not been solved. It has been made worse, though the character of the noise is improved to musical tones instead of just harsh buzzing and rattling.
2) Several failed test prints at ever decreasing jerk, acceleration, and speed settings have demonstrated that the old motor simply doesn’t have enough torque to drive the screw reliably at reasonable printing speeds.
Further research into the first problem indicates that the vibration and noise are inherent in using steppers, and worse in MegaMax than in machines that use NEMA-17 motors because of the higher detent torque in the NEMA-23 size motors. Detent torque is the little bump-bump you feel when you turn the motor shaft by hand. The solution to the problem is to use a good driver for the motor and a higher voltage power supply. The little A4988 chips in the Pololu drivers on the RAMPS board are very unintelligent- all they do is provide microstepping. They work OK for NEMA-17 size motors because of the speeds and low detent torques in those motors. When used with NEMA-23 motors the driver limitations become apparent – as they have in MegaMax- lots of noise and vibration.
Good stepper drivers are DSP based and automatically sense resonance and damp it electronically. They use phase controlled sine wave currents to drive the motors smoothly. Fortunately, DSP stepper drivers for NEMA-23 size motors are pretty cheap. Here’s video of the DM542a driver pushing a NEMA-23 motor around. I have ordered a DM542a driver.
The best power supply for stepper drivers is not a switcher, and running steppers from a switching supply will often result in a dead power supply. I will be building a simple, unregulated transformer, rectifier, and filter cap supply to go with the new driver.
Next came the question of how to determine how much torque is needed to properly drive the Y-axis. A bit of research took me here: Motor size calculator. You just select the scheme for which you want to size the motor, enter the appropriate data, and it magically tells you how much torque you need to do the job. When I ran the numbers on MegaMax, it told me that I need about 350 oz-in of torque (about double the torque of the motor I have). I did a quick search and found a Chinese made (of course) 425 oz-in motor for $50. Also on order…
The motor mount I am using is designed for a NEMA-34 size motor with which I use an adapter plate to allow the NEMA-23 motor to fit. Since I’m buying a new motor anyway, why not just get a NEMA-34 motor? It turns out that the best stepper for the job is generally the smallest motor that can provide the necessary torque. A NEMA-34 motor could provide much more torque but the detent torque and rotor inertia would work against smooth and fast operation, and require a bigger power supply.
The ATmega2560 and RAMPS boards will be replaced by a SmoothieBoard. It has a much faster processor, much better connections for motors/external drivers, etc. It currently lacks an easy way to add an LCD controller, so I may have to connect to a computer to start prints up (it has ethernet and a built in web server so it can be accessed from any computer on the network). When a clean way to add an LCD controller becomes available, I’ll add it. SmoothieBoard review
December 13 2014
I want to document some of my travels in a better manner. After looking around for a few map design inspirations, I came across the following example from a trek across Iceland.
So, I decided to create a map myself. I downloaded the following .SVG map of Scotland from Wikimedia.
Using Inkscape, I deleted other countries, external water bodies, and remote islands. I thought about a unified border color but I ended up really liking the representation of water versus land boundaries.
Looking better already! Now, I did not want to sit down and manually trace my journey. Since this file doesn’t contain any geographical information, my best bet was to somehow get my path in a vector format and manipulate it into the same scale, plane, etc., as map above.
I started by recreating the trip in Google maps engine. The train and bus journeys were easy to plot – it’s just like looking up directions in Google maps. Plotting a hike was a little bit more complex since I did not record my GPS location. I was lucky to find a .KML file from a better prepared hiker through a Google search and imported it into Google maps engine without any issues. I exported the .KML file when I was done.
The file was saved as a zipped .KML (.KMZ ) file so I used Google Earth to save it as a .KML. This is starting to sound like an ad for Google. I swear I am not a shill – Ask Jeeves is a much better search engine, see!
The .KML file was processed into an .SVG using my new best friend, Indie Mapper.
Since I only cared about the lines, I deleted the description and points using the menu on the left. Remember kids, always, and I mean always, read documentation. I spent a whole day scaling, rotating, skewing, bargaining, manipulating nodes, punching walls, trying to match the path output to the map from above. If I had simply read on the Wikimedia page, that the map had a Equirectangular projection and was scaled 170% in the N/S direction, I wouldn’t be writing this at 4AM in the morning. You can change the projection within Indie Mapper. Scaling was easily done in Inkscape later.
Export the file as a .SVG.
Yay! on three everyone yell, Compatible! Compatible! Compatible! Make sure you are alone.
Upon path import, the first step was to scale the height only by 170% to match the map’s relative coordinates. Then, the height and width were scaled proportionally till they “looked right.” I compared the relative location of the path to ocean and lakes (I really should say “Lochs”) in Inkscape versus Google maps so make sure everything looked right. Since I had the right relative dimensions, it only look a couple of minutes and Voila!
I manually colored the hike in green and motorized travel in red. If I decide to laser cut this file, I’ll vector “burn” the border and water bodies on lower power versus the path. I’ll keep playing around with the design and maybe add day hikes as well but I am happy with the results for now!
December 12 2014
December 11 2014
December 09 2014
December 08 2014
Scotland is a place that, for the average American, provokes strong reactions. Single malt Scotch whisky. Haggis. And bagpipes. At least in America, the thought of 3D printed bagpipes may inspire fear in some people. Bagpipes were considered weapons of war, and commonly thought to be banned following the unsuccessful Jacobite Rising of 1745. (The Act of Proscription 1746 doesn’t directly mention them, though.) Personally, I’m quite a fan of pipe music, as well as other Scottish folk music, such as the Corries, and the music of Nova Scotia, especially Mary Jane Lamond.
I bought a Highland bagpipe practice chanter years ago, only to discover that the angle I had to hold it to keep my fingers in the right position was torture on my wrists. I figure it would be more comfortable to play when attached to an actual bag. But acquiring a full set of Highland bagpipes wasn’t terribly practical, and that would probably lead to my neighbors breaking down my door and coming after me with torches and pitchforks should I try to practice indoors. Or at least they’d complain to the condo association. So I forgot about that for a while.
Then in spring of 2014 I saw the Dreaming Pipes Kickstarter posted by Donald Lindsay of Glasgow. He was creating a 3D printed chanter with a customized extended range for the Scottish smallpipes, which are, as their name suggests, smaller, and designed to be played indoors. But he was also creating plans for a full set of smallpipes modeled off a 17th century design that could be 3D printed, with a laser cut bellows. And he was also designing 3D printed Highland bagpipe drones. I’ve got access to four 3D printers and a laser cutter at Pumping Station: One. It looked like fun to build. So I backed it.
The project did run behind schedule, but at last I started receiving STLs and instruction videos for building the smallpipes. I posted on the PS:One list to see if anyone was interested in doing a group build, and one other member joined in.
The first decision: ABS or PLA. Both will work. ABS is more easily “machined” after printing, e.g. you can ream out holes to exact dimension more easily. But PLA allows for printing finer details and may be less brittle for the thinner walled sections of the pipes. So I’m opting for PLA and using the LulzBot TAZ3 printer.
Before printing any actual parts, I need to determine whether the printer will extrude the right inner and outer diameter. Donald sent along test files. After getting PLA (unfortunately, all we had on hand were weird colors, so I opted for orange) loaded and the printer heating, I checked online for the recommended settings. This printer has a 0.35mm nozzle, and the recommended Slic3r settings are 180C extruder, 50C bed, 0.14mm layers, no support, 100% infill. Unfortunately, Slic3r crashed on the test print. Apparently the rings were spaced too close together. Elizabeth helped me break the STL file into separate objects and move them farther apart on the build plate. This worked.
The next step was to measure them with a micrometer and send the results to Donald. I used a micrometer to attempt to measure the inner and outer diameters of the four rings. This was more difficult than it sounds. They seemed to spread out a bit and make a lip where they touched the glass build plate, so I tried to ignore the lip on the OD measurement. I’m also concerned the thinner ones might be flexing a little bit when I measure them with the micrometer. I tried to take 3 different measurements of each:
ID: 3.89, 3.90, 3.91 OD: 12.50, 12.52. 12.62
ID: 6.91, 6.92, 6.96 OD: 12.70, 12.76, 12.80
ID: 10.96, 10.97, 11.04 OD: 14.24, 14.27, 14.34
ID: 10.92, 10.96, 10.97 OD: 17.20, 17.24, 17.31
According to Donald, the first piece is the bore itself. No problem there. The second is the reed socket and should be 6.75 mm. But the reed has rubber wrapped around it, so it should still fit. The third and forth correspond to the tuning chamber, and they should all be uniform. This might be a possible problem if the slide doesn’t fit nicely, but I won’t know that until the drone is built. I can also try sanding it if I run into trouble, or using an insert of thin walled brass hobby tubing. So it looks like we’re ready to start printing smallpipes drones.
These also require reeds. Donald recommends purchasing from Pipe Dreams Reeds in Glasgow. They also sell the necessary beeswax coated hemp used to make a seal between parts of the pipes. So I contacted them regarding what reeds I should buy. I heard back, and it seems there may be some confusion between the original prototype smallpipes and the current version, so they’re getting in touch with Donald. Once they get back to me, I plan on placing an order for two sets of reeds for the three drones.
MegaMax has been and continues to be my main project for the last 2+ years. I am currently working on some upgrades that will make him more Mega and even more Max. The Y axis is being converted from belt drive to screw drive and the round guide rails are being replaced with linear guides and bearing blocks. The X-axis will also get converted to linear guide and bearing block and change from 5mm pitch belt to 2 mm pitch belt drive. I feel confident saying that once these modifications are complete the flaws/errors in prints will be due primarily to the nature of liquid plastic squirting through a nozzle, not positioning system errors.
I recently updated my web site with a sort of historical look at the project, including all the mistakes I’ve made along the way and the often failed attempts at correcting them. Here is the page that shows how it all started, how it has ended up, and where it is going. http://mark.rehorst.com/MegaMax_3D_Printer/index.html
Don’t ask me why I do this- I have no choice.
December 07 2014
NERP is not exclusively Raspberry Pi, the small computerand embedded systems interest group at Pumping Station:One in Chicago. NERP meets every other Monday at 7pm at Pumping Station:One, 3519 N. Elston Ave. in Chicago.
Andrew Kilkenny is a professional embedded Android kernel hacker. At NERP on Monday he will introduce Android as an emebedded OS. He’ll show functional demos, then after the meeting have a hands-on Android compilation festival. If you want to partcipate in the hands-on part, clear out some space on your hard drive for Eclipse and the Android Libraries!
The Android Operating system has revolutionized the embedded world. Originally developed for your phone, the Android Open Source Project (AOSP) enables the adaptation of the cell-phone oriented operating system into any product you can dream of. You can find Android in Airplane In-Flight-Entertainment Systems, in Washing Machines, and in Refrigerators. Any embedded system with an LCD screen can benefit from Android’s advanced Graphical User Interface (GUI) tools by rapidly developing Android Applications using the stock development environment. Join us for NERP where we explore how to use embedded Android on the BeagleBone Black (BBB) and Minowboard MAX. We’ll load the software, hop in on a command line, and twiddle some bits! We’ll also go over Android software architecture and practical applications of embedded Android. Following the NERP session there will be a guided demonstration on downloading and installing the AOSP and eclipse tools. A computer with Ubuntu (12.04 or 14.04) and lots of hard drive space will be needed to build the AOSP.
Find NERP and Pumping Station:One at
NERP – Not Exclusively Raspberry Pi
NERP is Not Exclusively Raspberry Pi, the small computer and embedded systems interest group at Pumping Station One in Chicago. (Chicago’s oldest and finest hackerspace.) NERP…
Monday, Dec 8, 2014, 7:00 PM
Doors open at 6:30pm. The next meeting is December
NERP is free and open to the public.
Ed Bennett ed @ kinetics and electronics com
Tags: electronics, embedded, NERP, Open Source,
raspberry pi, hackerspace, Beagle Bone, Element14, Pumping
Station One, IoT, Android
December 04 2014
Vi minner om juleverkstedet vårt, som holdes nå på lørdag 6/12 fra 11-15.
Dette blir på biblioteket, i andre etasje. Ikke i Digitalt verksted, men lesesalen til venstre når man kommer opp trappa.
Hvis du ikke har et julete prosjekt, ta med et annet prosjekt.
December 03 2014
A student from a local university reached out to us earlier this year to create a light based object for a class project. I volunteered to help her and after many iterations, we decided to build a diffused RGB Lamp.
The finger-jointed acrylic body was designed using makercase.com and laser cut.
I used the addressable RGB LED strip from Adafruit, called Neopixels, to provide the lighting effects. The LED strip was wrapped around a PVC pipe in a spiral so it could provide light on all four (4) sides. The spiral spacing gets tighter near the top to either to vary the lamp density for a cool effect or I got lazy since this was done at 1AM on a Monday morning – I’ll let you decide.
A Teensy 3.1 controls the strip using the Adafruit Neopixel library. Two (2) sets of three (3) rechargable NiMH batteries were used. At full charge, a bank provided 3.82 Volts. While the micro controller was running happily, the LEDs were noticeably dim. While the vellum paper diffused the lights effectively, the distance to the acrylic was relatively small, so brighter LEDs would have decreased the desired gradient effect anyway.
We cut the vinyl logo and border using a Silhouette CAMEO. The final design had to be mirrored since it would be adhered to the inside of the acrylic case using transfer paper. The text on the top did not cut very well so we’ll re-cut that bit with more optimized fonts. After seeing the results, I think I’ll create a lamp for myself as well.
We are delighted to partner with Dún Laoghaire-Rathdown Arts Office on some specially developed workshops for Soundings. These workshops are themed around radio and light-based communications, and take inspiration from Dun Laoghaire both as a sea port and as an important place in the history of radio transmissions. They are family-based, hands on, and mix old and new technologies so that participants will make something fun to take home. The workshops are lend by Jeffrey Roe and Sinead McDonald. In addition to the workshops Jeffrey’s ad Sinead’s Guzman Box will be on display. It will play a selection of historical radio pieces directly into the listener’s head. Details of the workshops are below.
Build a Skull Radio with TOG
Saturday 13th December 2014: 11.30am – 1.30pm
Have you ever wanted to listen to music without using your ears? Turn your own head into a speaker? The skull radio allows you to listen in total silence, by sending sound waves through your teeth! Join Jeffrey and Sinead and assemble a specially designed kit that allows you to hear sounds directly, using vibration.
*Age: 10 +
Crystal radio assembly
Saturday 17th January 2015: 11.30am – 1.30pm
AM radio is the oldest form of radio transmission and is still broadcast all over the world. In this workshop you’ll learn how to build your own AM crystal radio set using basic components and household items. TOG will bring along a short range microbroadcast transmitter on the day so you will be assured of a strong signal.
*Age: 10 +
Stealth Communications – Using light and sound to send encoded messages
Saturday 24th January 2015: 11.30am – 1.30pm
Ever wonder how ships communicated with each other and land before radio was invented? Before we could transmit voice signals? You can play the smuggler by building kits using buzzers and LED lights, and learn how to send encoded or silent messages to each other over long distances.
*Age: 10 +
All of these workshops take place in new Lexicon Library in Dun Laoghaire. They are free to the public but require pre booking.
To book email firstname.lastname@example.org or call (01) 271 9531
December 02 2014
- Carrot Cake
- Apple Jam
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