Taking temperature

Catching up on things.

Working on my Raspberry Pi lately.

Got my thermistor wired up.

I used a Thermocouple Amplifier MAX31855 breakout board and a Type-K Glass Braid Thermocouple from Adafruit.

Took a code sample from my Pi class for using the SPI protocol in Python. I combined that with an Arduino Sketch from Adafruit for the MAX31855 and surprisingly I got results the first time. Graphing the results against known temperatures (from my temperature sensing multi-meter) I programmed in software adjustments — not completely accurate, but close enough for now, within a couple of degrees.

Here is the Python program running on the Pi.


It takes a temperature reading every 2 seconds. The first column is the raw output from the MAX31855. The second column has been put through a software converter to give me Celcius. The last column is in Fahrenheit.

Here is the whole setup on a breadboard.


The Pi on the left. Breadboard on right with the MAX31855 in the middle of the board. The orange-yellow wire is the thermistor itself. Also notice a Pi Plate (blue) in the upper left. This will hold the project when it comes to soldering time. In the middle (blue on red) is a relay. This will be used to control the heater on the print bed.

Also have recently picked up 36 .22 ohm 5w resistors from U-Do-It Electronics. I will cement them on a replacement print tray made of aluminum in a combination of series and parallel. Power them with a power supply from a cast-off computer I got from a buddy.



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Something ridiculous

Here’s something ridiculously pathetically sad.

One piece to that Pi case I tried to print was posted to thingiverse upside down. I let it print for a while to see what I’d get.



Here it is.

I realize things on thingiverse are free and they’re worth what you pay for. I also realize someone went to a lot of trouble designing this object and putting into the public domain with no thought of profit. But come on! The sloppiness, the waste of my time, the waste of my filament, dude whoever you are … nah, I’d better not say it.

I’ll just say, “thanks, nice try, add some quality control when you release something to the world next time.”


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Gobs and gobs of gobs

Playing with the printer. I downloaded a case for my Raspberry Pi from thingiverse and tried to print it.

The first piece printed wonderfully.  Then when I loaded the 2nd piece into Pronterface, the printer would not take the command to “home”, that is go to x,y,z coordinates of (0,0,0). The z-axis, that is, the print bed, would not rise. Couldn’t get it to rise no matter how many times I turned the printer off and on, quit and restarted Pronterface, even restarting the Mac.

The next evening, I tried the steps again, just to document what’s going on. For some reason the print bed rose to zero immediately.

Here’s a video of the 2nd piece (actually 3 pieces) in one print.

Notice the bunched up plastic at the beginning. I thought I could recover from that, somehow. Skip to 1:30 to see things really get ugly.

Here’s another attempt …

Forward to 1:20 to cut to the chase.

Just look at that buildup smeared on the printbed!

Oh, how did I solve the problem of the print bed not rising. I’m not sure how, but as soon as each build finished I clicked “home” on Pronterface that seemed to do it. Not sure what would happen if I don’t “home” it right away.




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First impressions

The printer arrived nicely packaged. Included in the box was the printer, some tools (3 hex wrenches, a 7mm wrench, and a plastic screwdriver), stickers, and two sheets of paper. These two sheets are the entirety of the documentation. They basically tell me what the tools are for and where to download software for the printer tool chain.

No user manual of any kind.

The printer is a single-head extractor model. I was expecting a dual-head printer. That’s what was on their web page when I did my selection research. I even wrote asking about that. When I checked, Type A Machine’s website has nary a word about the dual-head extractor other than it will be re-released some time in the future. I looked for my posts asking about the Series 1’s dual-head capabilities. The posts were deleted. Fortunately I still have the emails notifying me of a response to my question, clicking through, I got a 404 page from the Type A site.

The lack of the dual-head is the one thing that pisses me off about the printer.

It’s Saturday morning of a long holiday weekend. I’ll be contacting them Tuesday morning for answers.


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Printer Arrived


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Waiting for parts

1 1/2′ HDMI cable on the way.

Printer s/b ready some time this week. Then about a week to ship. Tick. Tick. Tick.

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3D Printing

I’m just setting off on my adventure in 3D printing.

I’m clumsy, don’t know electronics, don’t know hardware. But, there’s plenty of information out there. The entries below chronicle what I’ve learned as I’m learning about the 3D printer world.

Feel free to post a comment.

If you have questions, I’ll try to help. But please be able to intelligently articulate your problem in technical terms. List what you’ve tried to solve your problem. List what documentation you read to gain understanding of your problem. Include what the manufacturer suggests you do to resolve your problem.

If you’ve done all that, be forewarned, you already know more about your problem than I.

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Today I got …

Order from Amazon:

Again, haven’t had a chance to play with the multiMeter. It’s the first one I ever had. It’s about time, too. Far as the printer filaments, 1 kg (2.2 lbs) spools are a lot smaller than I imagined. Hmm. 2 PLA and 2 ABS. Clear and white of each. Clear will be for the Pi case, first project.

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Raspberry Pi stuff arrived

Got my order from Adafruit. www.adafruit.com


Adafruit Prototyping Pi Plate Kit for Raspberry Pi
PID: 801
$15.95 $15.95

12V 5A switching power supply
PID: 352
$24.95 $24.95

HDMI/VGA/NTSC/PAL Display – 7″ Diagonal – 1280×800 IPS
PID: 1033
$159.95 $159.95

Thermocouple Type-K Glass Braid Insulated
PID: 270
$10.00 $10.00

Powerswitch tail 2
PID: 268
$25.95 $25.95

Mini DC/DC Step-Down (Buck) Converter – 5V @ 1A output
PID: 1065
$14.95 $29.90

VCNL4000 Proximity/Light sensor
PID: 466
$9.95 $9.95

Thermocouple Amplifier MAX31855 breakout board (MAX6675 upgrade)
PID: 269
$17.50 $17.50

Sub-Total: $294.15
Tax: $0.00
United Parcel Service (1 pkg x 3.43 lbs total) (UPS Ground (recommended) — FREE for orders over $250 –): Shipping: $0.00

Total: $294.15

Whoo hoo, see that, no shipping, no tax. (Those days are numbered.)

Haven’t had a chance to play with any of this yet. Just discovered I don’t have any spare HDMI cables at home.
Ordered the shorted one 1 1/2′ from Amazon.

BTW This will all be used to created a way-cool thermostat for my yet-to-be-built heated print bed.

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Uploaded all my offline log entries to this blog. I plan to keep this updated in a timely manner as I venture into uncharted territory (uncharted at least for me).

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