MakerBot Industries

iFauxn 4 Cash/Gift Card Trap by MatthewLaBerge

As Uncle Ben said, “With great power comes great responsibility.”  I’m afraid that one of our own Thingiverse citizens, MatthewLaBerge, appears to have been seduced by the dark side of 3D printing.

His gift to an indecisive family member was an iPhone 4 shaped plastic box with the actual gift inserted part way through the printing process.  Once the gift (seen above) was included, he un-paused the print job – completely enclosing the present inside plastic.  The sealed plastic case was then sewn into a felted sock and then wrapped in six skeins of yarn. ¹

It’s like the world’s first evil pinata.

1. Pretty much the only way to make it less accessible would have been to place it inside a secure cryptex. [↩]

“Okay, so I’ve opened the control panel and I’ve carefully adjusted my x- and y-axis to the center of the stage, with the nozzle just touching the build surface — and hit ‘Make Current Position Zero.’ Great! So when I run my print, my bot will remember this setting — !”

Actually, no.

When you hit “Build” for your print, your control panel  positioning vanishes with the first “G92″ command. The collective purpose for the commands at the head and tail of your gcode (the start.gcode and end.gcode sections) is to overwrite previous board states and values so that your bot behaves as you intend it to. Many of a MakerBot’s “automation” functions are actually declared in the gcode rather than established in the Control Panel or elsewhere for better portability for your designs.

The “begin homing” section is an important part of the start.gcode commands for a Thing-O-Matic. The values in this area declare the absolute positioning for the build envelope. Fail to pick the right values here, and your MakerBot might slam into the build platform or print in the air in its attempts to dutifully follow your instructions.

MakerBot Operators follow the Thing-O-Matic “Your First Print” build assembly instructions to find the z-height for their MakerBot by using the “calibration” script built into ReplicatorG . What happens when you enter this value into your start.gcode template (or manually in the gcode after skeining each print) is that your G92 command tells your bot (whose z-axis progress has just halted on a z-max endstop) that it is currently located at this particular z-height. All further absolute gcode positions are informed by this little number.

What might interest Thing-O-Matic users to know is that this is also true of the x- and y- axis values on the next line. Most users will do just fine with the defaults, but if you find that you are printing really close to the limitations of your build platform, you should take time to establish the absolute settings for your x-min and y-min endstops as well.

Here’s How to Establish x-min and y-min Endstop Homing Section Values

1. Locate “true center” for your build platform by dividing the “printable” width of your stage by two. Mark it!
2. Position your nozzle in-line with this position (can be a couple of centimeters up after you verify placement).
3. Hit “Enable” Stepper Motor Controls.
4. Click the button to “Make current position zero.”
5. Using the Control Panel, jog your build platform over in the direction of the x-min endstop (x minus direction). When you get close, gear down from larger values to just 1mm values. When even closer drop from 1mm jog down to 0.1mm jog.
6. When you activate the endstop, right down the negative value in the X position box.
7. Now hit “Center X” and verify that your nozzle is over true center again. (You might need to tune your x-axis min by a 10th of a millimeter or two.
8. Repeat Step 1-7 along the y-axis for the y-min value.
9. In the “begin homing” section of the gcode f0r your prints, revise “G92 Zxxx ( —=== Set Z axis maximum ===— )” to match your z-height, and “G92 Xxxx Yxxx (set zero for X and Y)” to match your x-min and y-min values respectively (should be negative values). You can copy and paste these two lines somewhere so that you can quickly grab them for any print you do — or add them into the start.gcode plaintext file in your Skeinforge profile in ReplicatorG.¹
10. Double the absolute value for the x-min and y-min values, and grab your z-height, and you have the current build envelop for your machine, (X, Y, Z)!

One More Special Note

Motherboard Onboard Preferences

If you experience weird endstop behavior, the first thing to check is the “Motherboard Onboard Preferences” located in the Machine dropdown menu for ReplicatorG. This is an example of a setting outside your gcode that remains in active use on the firmware for your control boards. Make sure that your “Invert Endstops” value is set to “Inverted (Default; H21LOB-based endstops)” as this value can be wiped by uploading recent firmware.

1. Your start.gcode file might be located in the hidden .replicatorg folder in your user folder if you created  custom skeinforge template. [↩]

Thingiverse citizen mirk brings us his engineering team’s setup for a do-it-yourself artificial sunrise lamp/alarm clock.  They connected a wall timer to a ceiling fan motor, connected to lots of printed gears, connected to a dimmer switch, connected to a standard light bulb.  If you were scavenging parts instead of buying new like mirk’s team, you might be able to build your own sunrise lamp for little more than the cost of the printed parts.

Artificial Sunrise Lamp by mirk

As a project for our electrical engineering (for mechanical engineers) class, and since Ottawa mornings can be extremely dark, me and my group decided to build a lamp that could simulate the sunrise during the morning to help with waking up. My modular gear reducers, which i posted about a month ago, were designed for, and played a huge role in, this project. Once built, the lamp plugs into a wall timer, and as long as the control switch is open (optional part) the lamp begins turning on as soon as electricity is applied from the wall timer. These kinds of lamps exist for purchase, but usually go for around $200. We spent around $70 total, but you could definitely build it for much less. Video at youtube.com/watch?v=9fHnanEdq4w

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Modular Gear Reducers by mirk

3:1 gear stages that can be assembled to get a gear ratio to any power of 3. I needed to reduce the speed of a motor by a large degree. My first tries used a a worm gear, but I didn't have my support settings dialed in well enough to print one yet. I went with this design so it would be easy to add or remove stages depending on the desired gear ratio. For my current project, I am using 6 stages of gear reduction. 3^6=729 so I have a 729:1 reduction in speed. Included with this is a 1:729 increase in torque.

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Here’s a MakerBot pro tip: you can combine your prints with OTHER STUFF!

That’s right, it’s totally possible to combine printed parts with stuff you have around the house or in the spare parts bin.  We usually see this with the emphasis going the other way — modifying another part with something printed.  Here, the BNC connectors are added to the printed chess pieces…a subtle difference that makes this chess set a little bit brilliant.  Good work, bryanandaimee!

Does anybody else have a novel combination to share?  Let us know in the comments!  Chess tips are also welcome.

BNC Chess Set by bryanandaimee

My seven year old is now collecting chess sets. I have a bunch of BNC connectors laying around. So here is a BNC chess set. There are two versions of the pawn. Skeinforge may complain about the king and or queen, but I ignored the errors and they print fine. I'm not enough of an expert to find and fix the dangling participles. Have fun. Update: added a mock bnc connector for those who are connector deprived. It is not dimensionally correct, nor functional, but it should work as a replacement in this chess set. You probably only need it in the knight, pawn and bishop pieces.

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