New electronics for the makerbot part 2

Here is my makerbot electronics as of Friday. Including the relay board, there are 7 boards involved in running the bot. I finished soldering the proto board to connect my Pro Mega to the Quadstep Friday night. I got everything torn off and installed my new board stack in place. Still some work to do for making it look nice, but it’s already a big improvement. Moving on to the software side, I had a heck of a time getting anything to load from the Arduino environment. After nearly 8 hours of debugging and finally loading the basic blink program via the AVR Isp port (which involved teaching the Arduino environment that my pololu AVR programmer is like an stk500v2), I discovered what was happening. It was toggling the blink Led every 2 seconds instead of 1! I triple checked the fuse settings against various AVR calculators and they were […]

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New Oscilliscope Part 3 – Screen Capture

With the TDS544A up and running, I decided to take a crack at getting data off of it. The scope has a floppy drive (but my laptop doesn’t), a GPIB port, and a printer card with both parallel and serial interfaces. The hardcopy menu has around 18 options for filetypes, and is capable of sending the screenshot to any of the ports or the floppy drive. Of the options available, I decided to try sending a windows BMP file over the serial port. I used a F-F null modem cable and a USB to Serial converter. On the program side, I started with this autohotkey script which spews data from your serial port into notepad. With a little bit of munging (removing anything to do with sending data, and removing some of the ASCII conversion logic), I was able to get and write BMP files. A full 640×480 color bitmap […]

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New electronics for the makerbot

Sparkfun had an awesome deal for people who liked them on Facebook, so I decided to come up with a project. I’ve been looking with envy at the RAMPS board for reprap, and wanted to start getting parts to upgrade my cupcake. A bit of research shows that it’s a stack of an Arduino Mega2560, a connector board, and a couple of Pololu stepper drivers. Ultimachine has a complete kit (solder yourself) for $150. Poking around Sparkfun, I found this collection of goodies for $143 (before the discount): Arduino Pro Mini MegaShield Proto QuadStepper Motor Driver FTDI Breakout I’m planning on using the Proto shield to act as a connector board between the Pro and the QuadStepper. I won’t have to add much to it to get the other RAMPS functions, and I probably have most of it in stock. I may even put in a 24V power supply and I’ll […]

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3D Printer update

I’ve finally started getting back into printing. I had a bunch of filament feed issues, and it was a combination of a loose hobbed gear, and the set screw part of one of the extruder drive gears started to fail. Fortunately, I had enough stability left to print a few spares (in addition to the 4 I had in reserve, just in case). I got everything going again, printed a few things, and was printing during the scope repair. Then this: This was a new failure mode, but not completely unexpected. I’m not certain if it was just a bad gear, or if the Skin plugin I was experimenting with was causing the gear to be loaded more than usual. The automatic extruder fan seems to be working though. I’ll video it next time I have the printer repaired.  

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New Oscilliscope Part 2 – Repair

Continuing work on the TDS544A, I got all of the electrolytic capacitors off, and cleaned the board with simple green and alcohol. I took careful notes about what value of capacitor went where, and how all of the cables are hooked up internally. I also noted any switch settings I could find. The Digikey order of capacitors and a brand new ultra fine tip for my iron arrived.Here we are mid process on getting all the capacitors back on. It turns out I did not order enough of the 33µF capacitors, so I ended up substituting the 10µF capacitors in some places on the logic board, and on the front panel. The Acquisition board got all the proper values, since it might be important for the RAM and other major signal processing elements. On the logic board, I replaced about half of the capacitors on the power rails with the […]

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New Oscilliscope Part 1 – Disassembly

We were cleaning out the lab at work, and throwing out older lab equipment, and I scored a Tektronix TDS 544A. The sticker indicated it needed to be repaired and calibrated, and it just wasn’t going to be worth it, so they were tossing it. I scooped it up, and I’ll have a few blog posts about the repair process. First, the good – It’s a 4 channel 500MHz digitizing scope with a color CRT screen. It beats the heck out of my older TEK T935A, which is an analog 2CH 35MHz scope. I think the biggest win is the ability to stop the scope and look at a trace, as well as much more powerful triggering options. Powering it on, it has a few faults in the self diagnostics, and research online shows that the main problem with scopes from this era are the aluminum electrolytic capacitors on the main […]

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Extruder fan controller

I brought my makerbot to the Reading Friends and Family Day to show at the Reading Robockets booth. I’ve been having some issues with the extruder skipping, and I think part of the problem is that the stepper motor that does the extrusion is overheating a little. MIT Swapfest was also this past weekend, and I got a number of small useful items, like a few of these fans for $1 each (including the finger guard). these fans are LOUD and move a lot of air.   One thing that I liked about the fans is that they are the four wire variety which means they can have speed controlled with a PWM signal applied to the blue wire. The base frequency is around 25 kHz, and the duty cycle controls speed (from 30% to 100%). I did a bit of research online, and came across a neat ieda for […]

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Hello again, world!

Whelp, I managed to drop my entire database while working on some web development…. The automatic backup didn’t work, and I have nothing to restore. I managed to get my blog content out of google’s cache, but it will take some effort to turn it back into blog posts, so this will be empty for a while….

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