We mentioned Ben’s “Loop the Lake” project a few weeks ago, and yes.. he made it back! In fact, he was at Maker Faire Milwaukee talking about his adventure, and he just did an interview with Wisconsin Public Radio about the trip.
Thank you again to Van McNeil and WISN 12 for their interest in Doors Open Milwaukee 2015! Historic Milwaukee has done a phenomenal job promoting and organizing this event for the last five years. If you haven’t had a chance to visit any of the 175+ buildings available this weekend, there’s still time Sunday from 10 AM to 5 PM. Be sure to check the full list of participants at the official Doors Open website:
Ben Nelson may be just a little bit obsessed with electric vehicles. Over the years he’s built an electric car and electric motorcycle, and he’s even got an electric riding lawnmower. He wanted to show the power of electric vehicles, so he decided to have his own “DIY Road Rally” and ride his Vetrix all the way around Lake Michigan.
All way way around the lake!? That’s 1,000 miles with no gasoline. He’ll be charging up a lot, but he knows where, when, and how to charge up.
People often say that electric vehicles are only good for short trips around the city, but Ben aims to prove them wrong. He’s also planning a full-length documentary film about his adventure…
The Singing Pumpkin controller continues along. This new spin of the board corrects the previous flub-up of the reversed amplifier pin-out as well as adds USB and RS-485 to the mix. There are some minor errors on the board, but nothing that has prevented 90% of the board function from being validated. I need to check the recv direction on the USB, the Arduino-style reset pulse, and the RS-485 transceiver. With that I’ll be able to work on generalized firmware and PC software.
This is your invitation to get out and explore Milwaukee! We’re just one of +150 buildings that will be open to the public on Saturday, September 19th and Sunday, September 20th between 10 a.m.-5 p.m. It’s free to attend and members will be present to answer questions and give tours.
If you visit, please enter at the north side of our building which is on Otjen Street. While you’re in the area, be sure to check out the rest of our neighborhood. There’s plenty of restaurants and shops within walking distance from the ‘Space.
MagneTag is a project I started about four years ago, when I first joined Milwaukee Makerspace. My goal was to create an electronic scoring system for physical tag games. As a paintball enthusiast I really enjoy the action and tactical nature of the sport. I was looking for a method that wasn’t messy or painful and 100% reliable .
In order to accomplish this goal, I employed the mystical power of magnets. It’s a scientific fact that magnets are awesome. I knew that the invisible forces created by magnets could be used to create electrical signals, the technology has been around since Maxwell wrote down his famous equations of electromagnetism. So I set out to build a wearable system that could electronically detect magnets, be they in some projectile, or embedded in an a foam gladiator weapon, or whatever.
To an experienced engineer, this might not seem like a huge challenge, but when I embarked on this project I could barely operate an Arduino. I didn’t really understand what I was getting myself into. Now, I have an above average understanding of the principles of electromagnetism because I have a two degrees in physics, but in trying to make my idea a reality, I now understand that theory does not get you very far on its own. Making things is freakin’ hard, and you have fail many times before you begin to really understand how much you don’t know. When it comes to making, there is no substitute for experience. And I learned this the hard way, over and over again. Persistence removes resistance. In the end I succeeded and created something even better than I had imagined.
Milwaukee Makerspace is an awesome place. I’ve had so much help from some brilliant members, and the tools we have access to are invaluable. I even met my business partner Jason at MMS. Without this place, MagneTag would have just been a cool idea I had one time. It never would have become a real thing.
This week marks a significant milestone in the history of our project: we are launching MagneTag on Kickstarter! We are going to put our game out there into the world and see if people really like it. Check out the launch video below, as well as a behind the scenes video, most of which takes place at Milwaukee Makerspace!
Chocolate printer progress continues. This week was devoted to the print cooling system. The chocolate will come out the extruder nozzle in a semi-molten state. It needs to solidify by the time the next layer of chocolate gets deposited on it, and I’d prefer it doesn’t drip or sag, so it needs to be chilled right after extrusion. The current plan is to blow chilled air over the chocolate just after it leaves the extruder. The chilled air will come from a foam insulated box containing a block of dry ice. There will be a blower pushing air into the box and a hose delivering the chilled air/CO2 to the print.
A couple weeks ago I got a blower from American Science and Surplus and this week I got it running by using a model airplane ESC and servo tester to drive its brushless DC motor. It appears to be capable of blowing much more air than I’ll need. There are many unknowns yet to test. How much chilled air/CO2 will it take to solidify the chocolate after it leaves the extruder? How long will a block of dry ice last when used this way? Will ice build-up inside the chiller box adversely affect its performance?
I designed and printed three parts for this system- a mount to attach the blower to a foam box up to 1.5″ thick, a hose coupler to allow delivery of the chilled air/CO2 to the print, and a hole saw to cut holes to fit the other two parts. The printed parts fit as if they were designed for the job!
This week I tried out a new DC-DC converter, the RT8293BHGSP, for my singing pumpkin controller. The issue I had with the old converter was that it was pretty expensive to get a 100uH coil that was rated for 4 or 5 amps. The most recent spin of the board only has about a 1.5 amp coil on it. This new converter runs at a little over 1Mhz as opposed to ~300kHz for the old converter. As such it can use a much lower value coil (10uH) that can be obtained in the 4 to 5 amp range for a reasonable price and with a reasonable package size.
This tester board seemed to work pretty well. It got plenty warm pushing around 2 amps, so it may need a heat sink. Still I’m pleased to have a solution that lets me get all the way up to the 3 amp limit of the converter.
My last post showed how I made a plunger for a 3.5 liter syringe. Today’s post is the results of the first ever test of that syringe assembly including the plunger. The goal of the test was to determine if the syringe pusher would be able to push very thick, viscous paste (sort of like melted chocolate) out of the 1/4″ syringe nozzle. It was also a test of the ability of the previously made silicone plunger to maintain a seal even against whatever pressure develops inside the syringe as it is pushing.
I mixed about 1 liter of extra thick pancake batter to a consistency that I thought would be much thicker than molten chocolate (pancake batter is much cheaper than chocolate) and shoveled it into the syringe, then bolted on the pusher and hooked it up to a power supply:
Looking back, I probably should have loaded the syringe from the other end.
Syringe loaded with super thick pancake batter.
Here’s the actual test. It gets especially interesting about 1 minute in:
The syringe continued drooling after power was removed due to air that was trapped inside the syringe. As the plunger pushed, the air was compressed. When the motor stopped the compressed air continued to push out the batter. I will have to be careful to eliminate air bubbles in the material when it comes time to use this in a printer.
It only took a couple minutes to clean out the syringe after the test was done.
The pusher did its job much better than expected, and the plunger held up just fine, too. I feel confident that this device will be able to extrude chocolate. Now the real work begins…
My latest project is a 3D printer that will produce chocolate objects. Like many other chocolate printers, it will include a syringe to dispense the chocolate. Unlike those other printers, the syringe in my printer will have 3.5 liter capacity to enable printing large objects.
The syringe is made from PVC pipe using mostly standard fittings. One piece that wasn’t standard was the plunger that fits inside the syringe tube and pushes on the chocolate contained therein. I had to design and fabricate the plunger. PVC pipe isn’t perfectly smooth or perfectly round inside, so I needed something compliant enough to ride out the pipe’s bumps and constrictions while maintaining a seal. The seal needed to be tough, yet safe for use with food because it will be in contact with the chocolate inside the syringe. I found some food-grade silicone casting material and ordered it.
While waiting for the silicone to arrive, I designed a 3D printable core for the plunger and a mold and jig. The core fits on the end of a linear actuator that will provide the push. The jig centered the core a few mm above the bottom of the mold. The mold was tapered and the widest part -the bottom- was a few mm larger diameter than the pipe, and several mm larger diameter than the core. The silicone envelops the core and is locked in place by holes that connect top and bottom side of the core. The plunger squeeze-fits into the pipe to maintain the seal against the uneven inner surface of the pipe.
Mold, jig, and core for syringe plunger
Mold, jig, and core for syringe showing core inserted into jig.
Mold, jig, and core assembled for silicone over-molding.
I measured and mixed the silicone, coated the core with it and then set the core and jig in/on the mold and let it cure for 24 hours. Then I removed the jig and broke the now silicone covered core out of the mold. Result: a perfect, tight fit inside the syringe tube.
Core in mold with silicone.
Finished plunger removed from the mold. The mold had to be broken off by design.
Plunger mounted on linear actuator.
The assembled syringe.
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.
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