This Saturday I continued with the commissioning of my unified singing pumpkin controller. I got all the sub-systems working except for the power amplifier. In the picture above, on the left is the pumpkin controller. On the right is a (normal) Arduino amplifier shield using the same amp chip. That shield works. If you look carefully you can see that the chip pins are mirrored between the two boards.
Mirroring pins is an innocent enough mistake. It happens to everyone once in a while. The problem is that I made the EXACT same mistake on the first round of that amplifier shield. (Notice the R2 on the right hand silk?) Apparently I fixed that problem manually without correcting my library symbol. That was many months ago and I forgot about it, thus resulting in a repeat of the same error on the unified pumpkin controller. Dumb mistake! It would have taken 10 mins at most to fix the symbol.
Don’t be like me, fix your symbols the moment you notice the mistake! You may not get back to it for a while and may not remember there was a problem.
A few years ago I made animatronic singing pumpkins using an Arduino Uno, a Wave shield, a 16-channel servo/pwm controller, and some DC-DC power converters, all from Adafruit. I designed a single PCB that unified all of that and included a 15W amplifier. Today I completed assembling that board and began its commissioning. I used solder paste and a mylar stencil cut on our laser. Its the first time I have ever soldered a TSSOP package with no shorts.
Anyway, I managed to forget to bring a microSD card, but the program loaded into the AVR OK and is running. All the various power supplies are outputting the correct voltage. 6 volts for the servos, 5 volts for the AVR, and 3.3V for the microSD card and buffer chip. The amplifer gets the raw 12 volts. So, I’m hopeful that over the next week I’ll be able to bring the board completely online.
I found this nice vase on Thingiverse and printed it at 75% scale a couple weeks ago.
75% scale vase looks fine from this angle…
It came out pretty good except for the area near the bottom where it was overhanging. 3D printers don’t handle overhangs without support material very well. I tried reslicing with support material added, but didn’t like the way it looked in either Cura or Slic3r so I didn’t try to print it again.
Overhang caused poor print quality for the first 6-8mm of the vase.
Then I tried printing it upside down- the overhang is much smaller.
100% scale vase printing upside down.
About 12 hours later, here’s the result: perfect!
The two vases, bottoms up- the 100% scale vase is perfect!
Hopefully a few crafters out there will appreciate the measures we’ve taken to protect tools that have been loaned to the group. Deterring misuse is only one feature of this upcycled sheet metal enclosure. It’s also incredibly stylish! A padlock could easily be added in the future, but surely it won’t come to that.
In following the internet chatter about the FTDI bricked-chip dust up some months ago I came across mention of a Silicon Labs USB-Serial chip, the CP2110, that worked a bit different. The device enumerates as a regular HID device and uses a standard OS driver rather than a manufacturer specific one. Being a HID device, there is no COM port. Instead you link a library into your application that knows how to engage the standard HID driver to talk to the chip in a serial-like fashion. In effect, this moves the driver from the OS to your application.
So I grabbed some of the chips and made up an OSHPark board that implemented the minimum passives and broke out the pins. Tonight, during Builder’s Night Out, I finally got around to soldering it up. The worst part about the CP2110 is that it is a 4mm x 4mm QFN with a 0.5mm pin pitch. I used the space’s 50W laser to make a solder paste stencil out of some of the giant roll of 3 mil mylar we have. My first go at it with one pass of the solder paste squeegee didn’t put down enough paste on the QFN and my second go with 3 or 4 passes in orthogonal directions put down too much solder paste. There is probably a middle ground there.
Anyway, I used the space’s Zallus reflow toaster oven to reflow that second paste attempt and wound up with a number of the QFN pins shorted together. (I should have wiped the paste off and looked for that middle ground.) To fix the shorts I used the space’s hot air rework gun to pull the QFN chip off. That allowed me to solder wick the pads to a point free of shorts and then use the hot air gun once again to put the chip back. I over heated and burnt the tantalum caps and the LEDs in that rework process. So I used the hot air gun to remove those components and then hand soldered replacements back on to the board.
The moment of truth came when I plugged the freshly soldered board into my laptop’s USB port. I fully expected it to say “over current limit”, but to my delight it happily installed the HID driver! I’m looking forward to trying out the link library.
This a follow up post to this one. I’ll list a few more ongoing classes and collaborative build efforts at our space.
This class is required before working in the ceramics and pottery area. It teaches you the general rules of housekeeping and basics of materials used in this process. Class details here.
Polymer Clay Basics
This class is designed to give you an overview of the Polymer Clay process. This medium can be used to make a wide variety of small accessories and jewelry pieces.
Felisha has been introducing the addicting process of wood turning to many makers. The beginner class covers tools, sharpening, turning spindles, basic work holding strategies, and finishing. By the end of the class each person will have completed a bottle stopper! Students actually learn on Felisha’s professional machine at Our Daily Salt. Class details here.
Trash to Cash
Tom had an ingenious scam idea to clean the makerspace. He shows you how to take a pile of junk and determine what has value and how to take it to the scrap yard and get cash for it! The money made from recycling is used to improve the space.
Keep your eyes open for more classes on the mailing list!
If I could summarize a makerspace with one phrase, it would be a, “place to share you skills.” This post lists a few ongoing classes and collaborative build efforts at our space.
Held for the first time last night, Marvin was excellent enough to teach Electronics 101 based on the lectures found here. A lot of our class attendees have can built circuits using existing schematics but don’t always understand the theory. This class hopes to bridge some of that gap. The class will be held every other Monday for the next 3 months. Next class should be on March 2nd at 7PM.
Lance and Chris have taught two Arduino 101 classes in the last 3 months on Saturday mornings using the excellent Digilent chipKIT Uno32 boards donated by Microchip. Details are on the wiki. The class starts from what an Arduino is, helps you with IDE installation, and you upload your first program to blink an LED! Watch out for upcoming 101 classes. I have heard whispers of an 102 offering as well…
Blacksmithing: Make your own Trivet
This class first describes, “What the Hell is a Trivet?” Then over 3 hours Dan walks a beginner through safety, forge operation, and basic blacksmithing. In addition to these awesome skills, you end up with a unique gift for a loved one. More details here.
Glass Etching Workshop
This multi-skill collection class is one of my personal favorites. After Pete’s initial class offering, Lexie has taken on the torch. In this class, you learn how to cut your mask in vinyl. You learn the software and hardware skills required to operate a vinyl cutter. You transfer the vinyl to a glass mug and sand blast the exposed areas. You end up with a beautiful product that also makes a great gift. Class details here.
Tesla Coil Build Club
A few members will start meeting on the second Sunday of each month to make a Singing Solid State Tesla Coil. The build will be based on this style. We’re all looking forward to see what they come up with.
I will list a few more classes in another post. Not to mention, there is so much learning, teaching, and collaboration that goes on every single day. So come on down and learn from us or teach us something.
September 26-27 at Wisconsin State Fair Park, the same weekend as Harvest Fair. Admission is free. Maker Faire Milwaukee's Call for Makers is now open.
Connect with Milwaukee Makerspace
Join our public mailing list to talk with Milwaukee Makers about projects, techniques and more.
Check out some behind the scenes info on our wiki.