I am building a machine that will dispense and mix ingredients to make a single cookie. The benefit is that each cookie on the sheet can have its own recipe, and the baker can sample all of the cookies to better understand how ingredient variations will affect taste and texture. In this video, I talk about the butter dispenser.
The folks at Meta Mate gave me the idea for customer-rating via QR code.
http://www.metamate.cc/
Tuesday, March 5, 2013
Hacking a milligram balance (scale) with a Parallax Propeller microcontroller
For an upcoming project, I'd like to develop a dispensing system that can measure out a desired mass of material. The idea would be to use a microcontroller, dispensing valve, and electronic balance to provide feedback. I already have an American Weigh Scales miniPro-100, and decided to hack it so that my microcontroller can discover how much mass is on the balance. It can then regulate the dispensing valve appropriately.
The balance contains a Cirrus CS5530 24-bit ADC. I tapped the clock and data lines and found bursts of data that occurred at 7.5Hz. The clock is about 150KHz. I used a Parallax Propeller running assembly in one of its cores to capture the data stream and load it into my main program.
The balance contains a Cirrus CS5530 24-bit ADC. I tapped the clock and data lines and found bursts of data that occurred at 7.5Hz. The clock is about 150KHz. I used a Parallax Propeller running assembly in one of its cores to capture the data stream and load it into my main program.
Monday, February 11, 2013
Cleaning a high-vacuum Penning gauge (cold cathode vacuum gauge)
My high-vacuum Penning gauge has been having some problems lately. The last time that I "fixed" it, I used lead solder to create a crushable metal seal between the parts of the gauge body. Eventually the rosin leaked out and probably caused contamination within the gauge.
I bought some Indium wire on eBay to replace the metal seals after cleaning the gauge with a bead blaster, sandpaper on glass, and lots of alcohol swabs.
Proper explanation of Penning Gauges:
http://www.thinksrs.com/downloads/PDFs/ApplicationNotes/IG1hotapp.pdf
I bought some Indium wire on eBay to replace the metal seals after cleaning the gauge with a bead blaster, sandpaper on glass, and lots of alcohol swabs.
Proper explanation of Penning Gauges:
http://www.thinksrs.com/downloads/PDFs/ApplicationNotes/IG1hotapp.pdf
Monday, January 21, 2013
Rheoscopic coffee table
I've received a few questions about my coffee table, which I built in 2006. I used fairly standard woodworking techniques (floating tenons, breadboard ends) with maple, walnut, and bloodwood for contrasting colors. I didn't use any stains or colored finishes -- all of the color is from the wood's natural appearance.
The table has a 30" diameter disc that contains about 2 gallons of water mixed with Pearl Swirl fluid. This fluid is essentially very fine glitter that becomes suspended in the water, and will show flow currents as the water moves within the disk. I positioned the disc on a 24" diameter lazy susan bearing for low-friction rotation. When the disc suddenly changes rotational speed, there will be turbulence in the water, which causes the rheoscopic fluid to show fluid vortices and eddies that are part of the turbulence.
The outer metal ring was custom-built by a shop that specializes in metal rings (see sources below). All of the other parts were bought from McMaster, eBay, and Steve Spangler Science for the Pearl Swirl fluid.
I got the idea for this table after see a tornado visualization exhibit at the Carnegie Science Center in Pittsburgh. The Exloratorium has an orb filled with a similar fluid to show flow patterns similar to those on a rotating planet with an atmosphere.
The main pieces are: 3/8" thick glass top, aluminum ring with L cross-section, a 3/4" thick O-ring with square cross-section and a 1/2" thick PVC plastic bottom. There are a bunch of screws that pull the aluminum ring down onto the glass, which pushes onto the O-ring, which pushes on the PVC bottom. There is no glue used anywhere in the disk. The overall diameter is about 32".
The disk holds about 2 gallons of liquid, and weighs a total of 80 lbs (just a good estimate -- I never measured it). There are two threaded fill-holes with plugs on the bottom, and the whole thing sits on a 24" lazy susan bearing.
These are my sources:
Glass top
http://www.glasstopsdirect.
3/8" thick tempered $85 shipped
Outer metal ring
http://www.nmfrings.com/rings/
Custom 2" x 2" x 3/16" thick, angle-in, "L" cross section, 32" outer dia
about $150 shipped
O-ring
http://www.mcmaster.com/
3/4", square cross-section, O-ring cord stock -- I made a scarf joint
to make this into a ring, about $40
Bottom plate
http://www.mcmaster.com/
1/2" thick gray PVC plastic $100
Fluid
http://www.
$20
Get some food coloring too
Screws, cushioning rubber, stuff to wire-brush the aluminum ring:
http://www.mcmaster.com
$30
lazy susan bearing
eBay -- search for "aluminum lazy susan"
12" will not work, you need to find a 24" dia bearing on eBay
$50
The table has a 30" diameter disc that contains about 2 gallons of water mixed with Pearl Swirl fluid. This fluid is essentially very fine glitter that becomes suspended in the water, and will show flow currents as the water moves within the disk. I positioned the disc on a 24" diameter lazy susan bearing for low-friction rotation. When the disc suddenly changes rotational speed, there will be turbulence in the water, which causes the rheoscopic fluid to show fluid vortices and eddies that are part of the turbulence.
The outer metal ring was custom-built by a shop that specializes in metal rings (see sources below). All of the other parts were bought from McMaster, eBay, and Steve Spangler Science for the Pearl Swirl fluid.
I got the idea for this table after see a tornado visualization exhibit at the Carnegie Science Center in Pittsburgh. The Exloratorium has an orb filled with a similar fluid to show flow patterns similar to those on a rotating planet with an atmosphere.
The main pieces are: 3/8" thick glass top, aluminum ring with L cross-section, a 3/4" thick O-ring with square cross-section and a 1/2" thick PVC plastic bottom. There are a bunch of screws that pull the aluminum ring down onto the glass, which pushes onto the O-ring, which pushes on the PVC bottom. There is no glue used anywhere in the disk. The overall diameter is about 32".
The disk holds about 2 gallons of liquid, and weighs a total of 80 lbs (just a good estimate -- I never measured it). There are two threaded fill-holes with plugs on the bottom, and the whole thing sits on a 24" lazy susan bearing.
These are my sources:
Glass top
http://www.glasstopsdirect.
3/8" thick tempered $85 shipped
Outer metal ring
http://www.nmfrings.com/rings/
Custom 2" x 2" x 3/16" thick, angle-in, "L" cross section, 32" outer dia
about $150 shipped
O-ring
http://www.mcmaster.com/
3/4", square cross-section, O-ring cord stock -- I made a scarf joint
to make this into a ring, about $40
Bottom plate
http://www.mcmaster.com/
1/2" thick gray PVC plastic $100
Fluid
http://www.
$20
Get some food coloring too
Screws, cushioning rubber, stuff to wire-brush the aluminum ring:
http://www.mcmaster.com
$30
lazy susan bearing
eBay -- search for "aluminum lazy susan"
12" will not work, you need to find a 24" dia bearing on eBay
$50
Sunday, January 20, 2013
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