Whoa. My fabber just ended up on the front page of both the Makerbot and Thingiverse blogs.

http://blog.thingiverse.com/2011/01/13/belfry-fabber/
http://blog.makerbot.com/2011/01/13/scratch-built-bot-belfry-fabber-mk1-rev6-by-revar/

Revision 6 of my home-build Belfry Fabber Mk1 plastic extrusion 3D Printer.



Since I slowed down my feed rate to nearly match my extrusion rate, my builds have improved in quality immensely. I'm even starting to experiment with using ABS support structures for overhangs. I still need to either tweak my oozebane settings, or move to a stepper extruder, but I've been really happy about my builds on this latest machine.

My roommate tugrik is experimenting with making French Onion soup again. The last time it was delicious, and I suspect this one will be even better. But he just sliced up ten whole onions in the kitchen, and even in the living room, half the house away, it's making my eyes water and sting. Yeeeeeg.

The stock CupcakeCNC 3d printer plastruder, which I've been using, has a timing belt pulley to drive the plastic filament through the extruder. Unfortunately, it has an annoying habit of stripping the filament, getting plastic stuck in its teeth, and stopping extrusion.

Some folks have been experimenting with alternatives, like a small worm gear, and have reported great success. Since I've been frustrated at the extruder, I decided to make a small worm gear on my lathe. See the pic below.

Belfry Fabber Mk1 I've been busy lately, adding a couple features to the Belfry Fabber Mk1. I've added a heated platform, an LCD display for status info, and a keypad to control the Fabber without a computer. I can start, pause, and stop print jobs from the SD Card, set head and platform temperatures, move the X, Y, and Z axes, zero the axes, and start and stop the extruder, all with just a few keystrokes.

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I just modified my 3d printer slightly to talk to an LCD display over the I2C bus. It shows position and temperatures currently, without having to be tethered. The display module can have a keypad attached to it, so I plan to have a menu button that would let you control the fabber and select files to build off of an SD card without a computer connection. Exciting stuff!

Me: Hey, which calipers are these?
Tugrik: The broken one that we were gonna disassemble because they skip if you don't hold them vertical.
Me: Cool. *takes them to workbench*

(Ten minute of disassembly pass.)

Me: Huh. *futzes with myriad parts.*

(Ten more minutes pass with me re-assembling.)

Me: Umm, I really wasn't trying to, but I seem to have accidentally fixed the calipers.

I have found a new level of Lame. I have Keypad Lust. While surfing Digikey looking for cheap membrane keypads to hook up to control my fabber, I ran across this decidedly NOT cheap keypad, pictured below. And Drooled. Luckily it's upwards of $150, so I'm not in any danger of ever spending my money on it.

I just ran across some Solid State Relays cheap on Digi-Key ($12 each), so I bought myself four of them.

For those of you who don't know, a Solid State Relay (SSR) is a nice little component that lets you take a low voltage, low current control line — from a micro-controller, for example — and use it to switch a higher voltage, high current line. In this case, I can use a 5 Volt DC output from my Teensy++ controller (with only ~10mA draw), and switch up to a 250 Volt, 25 Amp AC line. This means it's capable of switching standard 120V AC US wall power with lots of capacity to spare.

Hooking it up was ultra-easy, as I cannibalized a power strip to get sockets and wall plug. I just interrupted the hot line with the relay, hooked the SSR inputs up to my Teensy++ micro-controller, and moments later I was having the Teensy switching a light on and off. Since the SSR is so beefy, I could hook power tools and AC motors up to it if I wanted to.

What I plan to do with this is to use one of the SSRs to let my Fabber unit's electronics switch a high-current AC heater pad on and off, so my build platform can have a reasonable warm-up time. I also have vague plans for having a Christmas light display next year that can switch a number of light strands on and off in a synchronized way.

As unbelievable as it may seen, I've actually published an update for Trebuchet for Windows, Linux, and OS X on sourceforge. The update is not available for auto-update, as that system is problematic for various file permissions reasons.

This version (1.075) provides per-world selection of character encoding, and some support for MSP Mud Sound Protocol, as well as various small bugfixes.

You can fetch the latest version for your platform by going to https://sourceforge.net/projects/trebuchet/

There's a wide range of Microcontrollers out there for all sorts of purposes, but I've noticed a definite progression.

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The reason I've not been posting all sorts of pics of things I've made on the 3D printer is that, other than the initial teapot, I haven't gotten anything successful.

For a while it was software issues with settings of Skeinforge, the model slicer I use. It has dozens of cryptic settings. The results are infinitely tunable as a result, but to get good, much less usable results, you have to find the "magic settings" for your machine's speed and plastruder. Skeinforge's user interface... is painful. It was obviously designed by an engineer to be able to do Amazing Things if you have a Masters in Plastic Extrusion Technology. But it's barely usable by folks who just want to print 3d objects. And the app is sloooow. If anything is going to make me spend another year of my life writing a replacement app out of frustration, this'd be it.

I also kept running into meshing issues with the STL models I was using. Blender was great for pointing out meshing errors, but I couldn't figure out how to use it to FIX the problems. The auto face add feature didn't do it's mojo on the model I was working on, and I don't know Blender's Way Of Thinking yet. In fact, it's almost actively hostile for newbies to learn, despite the numerous tutorials available. Steep. Learning. Curve. And with my general lack of memory, I end up having to go through the tutorials over and over. On a laptop without a numeric keypad, or a 3 button mouse, you have extra config setting hoops to jump though to make it even usable. Meh. Supposedly Blender 1.5 will fix a number of the more egregious UI issues. I hope so. In any case, I found another open source app called Meshlab, which Just Works and was intuitive for the most part. It let me quickly fix up the holes in the model that made it non-manifold (Not water-tight). Blender pointed me to where the holes were, Meshlab fixed them easily.

Next problem was my machine itself.. I was having backlash and slippage issues with the belt drive. I ordered thinner belts from McMaster Carr and tightened them down well, and that made a world of difference, but I was still occasionally getting slippage. I've determined that lithium grease is too viscous for my uses here. Switching to some air-tool oil for the sliders made it run much smoother on the X and Y axes. I probably should find a more permanent oil, but for the moment, I can periodically re-lubricate.

I'm starting to build up a variety of failed prints of skulls. I was originally trying to print some for Halloween, but now it's my test object. I will soon have the world's largest collection of replica skulls of people who failed to live through The Philadelphia Experiment. In fact, I seem to have just made another one. Drat.

My first (and only so far) successful print was the Utah Teapot, which tugrik posted a picture of, which I'll re-post here.
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Dusty, you need to come over and play Brütal Legend on the 360. I won't be home this weekend, but you should come over and play it anyways. It's in the Xbox. It's very silly, and very metal, and very fun.

<Palpatine>Now witness the power of this fully Armed and Operational battle 'struder!</Palpatine>

Click here for video of running extruder

I've gotten the 3d printer finished!


But it ran only a few minutes before the extruder head ate itself, and melted it's PTFE thermal barrier. Booo! I have a new one and spares on order.

It's quieter than I expected, which is good. The final build area looks like 7.5" x 6" x 9". I managed to hide away all the electronics underneath, except for the extruder controller. A short circuit nearly fried my extruder controller, but I was able to solder up a bridge past the fried traces. I still need to set up my opto-endstops, but that's mostly just a wiring issue.

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Tasks completed today:

• Designed and built X-axis table mk3 for CheesecakeCNC.
• Soldered up 6 opto endstops for same.
• Assembled, updated the firmware of, and tested Gen3 electronics.
• Lasered out the parts for the mk4 plastruder.
• Started designing the Y/Z frame.
• Lasered 50 plaques with artwork for an unrelated project.
• Lathed a car pully for a friend.

...

Okay, maybe it was a productive day. :)

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So far with the screw-based drive for the X table, I've been able to get a speed of 15 inches per minute with the NEMA-17 stepper motor. I was thinking that this wasn't too bad, as my experience with the CNC TAIG mill was that I could get 45 inches per minute out of the larger NEMA-23 motors.

But then I saw a page talking about the feed rates used with the newer plastic extruder head, where they were talking 45 mm/SECOND feed rates, which translates to about 106 inches per minute.

...

Okay, the screw drive just isn't going to manage that. The plastic wants much faster than I could hope to get with the 20:1 gear reduction the lead-screw provides. It might be fine in metalworking, but not for plastruding. So back to the drawing board CAD.

ACE hardware seems to be rather lacking in the supply of belts and pulleys. I'm going to take a look at possibilities of using chains and sprockets from a bike or auto store, but things are looking bleak for using easily found off-the-shelf parts. I may have to settle for merely making a super-sized CupcakeCNC type design, with just mostly off the shelf parts. Well, I can live with that. McMaster-Carr has plentiful options of pulleys and belts, at the least.

So, the project description is now throttled back to:
How to make a 3D printer like the CupcakeCNC, but that can print larger items, using the same plastruder and electronics, and parts from any ACE hardware affiliate store, and a couple parts from McMaster-Carr.

Doesn't exactly roll off the tongue.

On a lighter note, I've decided that I'm going to call my design the CheesecakeCNC. It's bigger than a cupcake, and definitely cheesy in design.