Sunday, June 20, 2010

Marathon Man

So, I fixed the temp sensor. Or really, I replaced it. With a simple firmware hack (and installing scons) I moved the probe reader to a separate board, which is a more reliable system anyway. It also means that coupled with the heated platform board, my extruder controller now has "ears." I like that.

Now, my project partner and I just graduated from high school, and there was a celebratory party yesterday. At 4pm we began trying to run the now functional printer. First, I managed to strip the filament, and then in removing it I tore the leads off the heatercore. That was dumb. However, we dipped into the club supplies and made another one, and soon had an entirely fresh hot-end. We figured that with a fresh nozzle and barrel we might as well try and make it print with the PLA we bought, right?

Fast forward to 7:30am on the next day. The short answer is no. After a pretty solid block of more than 12 hours, the machine is extruding, but not reliably. We're seeing overheating on the board, barrel jams, slipping idler wheels, the works. Temp sensor hardware works great though. I am not a big fan of PLA now, but I am thinking we can solve some of this with better understanding of using PLA and a stronger extruder. We are using the new MK-5 pulley from makerbot, and it's great on ABS. It's not really biting the PLA though.

I'm amazed I am still awake, but evidently this is good project for keeping myself conscious with.

Thursday, June 17, 2010

Beautiful Music

Well, the extruder controller bug has been narrowed down.
The issue only surfaces if the sensor is plugged in, when the control panel is opened.
I presume this is because it is crashing when reading the sensor, and when it's not attached the circuit is returning something reasonable.
I'll be borrowing another controller soon, and in the meanwhile this one will have to be fixed properly.

In the meantime, I've been playing a lot with mid2cnc, playing pretty much anything I can find in midi format on the steppers. Flight of the bumblebee is a terrific test of printer speed. I ahev built up a pretty large library of midi files and their corresponding gcode, depending on whatever legality issues there might be I'll upload them. Also, I am fairly confident that I am the first to play Touhou theme songs on a 3D printer, but if I am not please let me know.

I've got a video of the machine playing, but I forgot to change the camera out of mirror mode, so I have to flip it horizontally.

Friday, June 4, 2010

Mad Extruder

We got the entire machine up and running for about two days. After a perfectly ordinary print, powerdown and sleep cycle (my sleeping), the machine started reading the temperature sensor wrong.
Completely wrong. With no thermistor attached the machine reads assorted temperatures between 100 and 220, but not the expected 255. After I tested the pins with a voltmeter (sensor attached), the readings were correct... for a short period. After 1-2 seconds of reading correctly the "temperature" skyrocketed back to 2XX. The same results can be had with another thermistor, so it is definitely on the board. An interesting note was that when heated to around 200 degrees Celsius the board begins to read the temperature correctly, and is able to regulate it fine.
However, given the complete unreliability of such performance I deemed that unacceptable.
A little help on the IRC indicated that either the resistor (4.7kohm) or capacitor (10uF) was damaged. I have no way to know what damaged them, but evidently something is broken. I probed the resistor, and got the correct resistance, but I managed to damage it by trying to re-seat it on the pads -- knocking off the soldering pads on the component itself. As I do not have spares of the parts, I scrounged and found the needed bits on some assorted and functional boards in the scrap pile, and replaced the capacitor and the resistor.

The board runs the extruder test program fine, and takes reprogramming correctly. However, it no longer communicates with the mainboard. This could be the side effect of re-seating a number of the components, as I felt like some were not well seated. I have yet to test the pins on the chip used to communicate over the cat-5 cable.

The timing could not be worse, because our PLA is now just sitting there, waiting, begging to be used.

Tuesday, June 1, 2010

A month of updates?!?

It's been a month since this updated? When did THAT happen?We've spent many more hours configuring the machine, changing various bits of the hardware and software, and we finally have it printing very well. Skeinforge took a lot of work, but the 20-odd hours poured into debugging nearly all of the options available were spent well.
We also constructed our very own heated build plate! Three times! The first time it was not strong enough, with an 8-ohm wrap, the second was too strong with 4-ohms (and burned up!) and the third try is 6-ohms and performing GREAT with a blue painter's tape surface.
Our heated build plate is essentially just a twirl of nichrome wire taped to a brass plate, with a plywood base and acrylic mount, with ceramic "tape" insulation inside. The top of the plate hits a reliable 90-110ÂșC in around ten minutes, and the makerbot firmware supports the reprap temp sensor 2.0 attached to port A6. The whole thing is pretty awesome.
Here's a picture of that, without the tape on it.
Those bolts that stick out are a little irritating, and I am working to make them obsolete. We've only head-crashed into them once, but it was truly nerve-wracking.

On the subject of nerve-wracking, skeinforge on my partner's machine self-destructed, and we cannot seem to restore it. Basically, we were running the raftless version, and when updating to the newest standard version it overwrote all of the settings. Now the raftless version is completely broken. This means we have only one machine that can run skeinforge well, yet Replicator G chokes and freezes, pausing the motors or extruder (but never both!). The fix for this has so far been to clone the copy of replicator G and skeinforge between machines, but we have not finished that yet.

In other news, we're using the new MK-5 Drive wheel from makerbot, we totally impulse-bought two of them. They're amazing, and we get something around 25mm/s at maximum motor speed. The insulator is showing some over-pressure wear and tear, but we can reinforce it/replace damaged ones.

We've ordered some awesome PLA from ultimachine, and as soon as it's here (measured in hours!) we'll be printing the first successor machine, probably a standard reprap mendel. Unless of course we decide to aim cheaper.

I hope to post again before a month passes, but with how busy I have become with work on this machine and work in school I do not know when my next chance will be.