Tuesday, June 21, 2011

Far too long

Well, this post is irresponsibly late (six months so)!
It's to be expected perhaps, when working and taking classes, and largely ignoring my printer, but it feels wrong. So, here's a recap of things that have been changing.
I've removed the heated plate while working with PLA, because blue tape works by itself so well... and because I damaged the temp reading board it was using.
The Makergear Brutstruder is working gracefully, with no issues whatsoever after the initial hiccups of breaking it in.
The linear bearings are holding out very surprisingly well, given how cheap they were to build. I temporarily swapped them with a Mendel inspired x and y carriage lowrider, but found that the rod stainless steel rod that was bearing the weight was stripping, and became ruined. I expect that this was a result of bad tolerances on the part of the printed components, and will try again with some slightly redesigned parts.
On a whim, I moved the Z-belt under the 'roof' of the printer's body, as wires (and fingers) were catching in the pulley. It works just as well, and has not yet constricted a build's height.

CupCakeStrap was able to produce parts for two Prusa Mendels before needing repair (about 30 hours printing, total). One of these Prusa Mendels has been constructed and supplied with sixth-generation electronics, and now software issues are being ironed out. Getting the Teacup firmware to play nicely with Replicator G has been a chore, but it's nearly functional as a printer.

Tuesday, December 7, 2010

I'm making a note here.

Huge success.
After months of mostly ignoring my little CupCakeStrap, and tending to things in my life like gainful employment, education and whatnot, and I've restored the printing ability to the bot!

Many things have been changed, but the important ones are all I will recount for now. I've swapped out my never-really-worked mk4.5 extruder for Makergear's terrific Stepper Extruder, and suddenly everything "just works." I can dial in the worst settings ever, and as long as the temperature is about right, it prints. The clear PLA I got is no longer sitting unused, instead I have printed a good ounce of it into testing cubes, ipad stands, reprap power rings, and assorted do-dads. Now I'm focusing on tuning the profile, based on help over on #makergear and #reprap. Pictures to be posted soon.

Saturday, July 10, 2010

Success, Failure, Rinse, Repeat.

The controller bug has been conquered, by way of modified and recompiled firmware. A new extruder thermistor pin and a new thermistor table were all that I needed to get it up and running, and installing the mac ports of the various tools took less than an hour of concentrated effort.
Before I fixed the software I borrowed a techzone Mendel electronics set to use in case my hardware was irreparable, in return for a checking over of all the solder connections, a good testing, and some printed mendel parts. The stepper boards and motherboard initialized, and tested correctly, though I did not do any heavy lifting on them. The extruder controller is a totally different story. I wired myself a simple adaptor to turn the cat5 cable my motherboard uses into just the two serial comms wires used by the reprap wiring. This seems to have worked fine, I am incredulous that there could be something dangerous in two serial lines at 5v. When I plugged it all together and flipped the switch, above the fan spin up noises there were two distinct "pop" sounds and one particularly painful sounding hiss. I cut th
e power, and saw what I believe was the magic smoke escaping something on the extruder controll
er. I have not yet found out what parts burned, but I cannot find any visual leads with my naked eye. I re-checked all my wires, and tested the power rails, and found no issues. The controller board's power LED lights, but nothing else seems to work. I suspect it t
o be dead.

After bearing this news to the owner of the boards and promises to help repair the damage -- whatever it turns out to be -- I turned my attention back to extruding w
ith my own hardware.
The same guy who lent me his boards also gave me a nozzle that he
had cut with machines available at the University of Washington. I was not expecting a success from the first try, but the part, a combination nozzle and heatercore, managed to work on the first try with PLA. My mind was blown. We got to extrude at 255PWM, resulting in 33mm/s from the nozzle for at least 5 meters of testing extrusion. However, reality restored the normal order, and the nozzle jammed as soon as I stopped the extrusion to prepare for a print. I suspect this is because the thermal gradient is so tremendously long, as the entire hot part is 1cm long, followed by 2-3 cm of blank heater barrel The thermistor is a 3mm one, and placed just before the barrel enters the insulator. I will shorten it somehow and try again later this week. If this design works out my project will have spawned what I think may be another unique upgrade.
In trying to unseat the jam we seem to have burned out the Kysan 1156006 gearmotor. I am not sure what happened, but it no longer runs, even from my bench power supply. I'm working to replace it now.
In older news, I laser cut our machine a very nice filament spool and box, based 99.9% on the makerbot MK1 Filament Spool. Wheras the makerbot version runs $100, mine cost me $2 in metal nuts and bolts, as the handsome plywood was cut from free scraps, and the plastic was donated. It works pretty great, though I had to make my own feed tube modifications to get PLA to bend nicely and draw without kinking up. I think ABS would be perfect, but PLA is my target material. I'll just laser cut myself another one later...

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.