Magnetic / spring loaded ball bearing

Diameter of the ball is 12.70 mm. Diameter of the thread is 5.00 mm. cDSC_0003

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Steel tube, Outer diameter 6.00 mm, length 230.00 mm
M5x20 set screw x12
Neodymium magnet, diameter 8.00 mm, height 8.00 mm x12
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M$ Windows requires specific USB chip driver on Arduino Mega board.

I’ve been assisting a DIYer to build Mini Kossel for few weeks.

Windows XP and Windows 7 failed to recognize Arduino Mega board. It turned out that Windows driver for the USB communication chip installed on Arduino Mega board needs to be installed.

http://www.arduino.cc/en/Main/ArduinoBoardMega2560

Communication

The Arduino Mega2560 has a number of facilities for communicating with a computer, another Arduino, or other microcontrollers. The ATmega2560 provides four hardware UARTs for TTL (5V) serial communication. An ATmega16U2 (ATmega 8U2 on the revision 1 and revision 2 boards) on the board channels one of these over USB and provides a virtual com port to software on the computer (Windows machines will need a .inf file, but OSX and Linux machines will recognize the board as a COM port automatically. The Arduino software includes a serial monitor which allows simple textual data to be sent to and from the board. The RX and TX LEDs on the board will flash when data is being transmitted via the ATmega8U2/ATmega16U2 chip and USB connection to the computer (but not for serial communication on pins 0 and 1).

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Nikon AF-S Nikkor 18-55 mm lens hood

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Download

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OpenSCAD – how to create Hangul text

OpenSCAD version 2015.04.01.nightly (git 90094ff)

$ sudo apt-get install openscad-nightly
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
libboost-filesystem1.49.0 libboost-system1.49.0 libglib2.0-0 libglib2.0-bin libglib2.0-dev
libharfbuzz-icu0 libharfbuzz0b libpango-1.0-0 libpango1.0-0 libpangocairo-1.0-0 libpangoft2-1.0-0
libpangoxft-1.0-0 libqscintilla2-8
Suggested packages:
libglib2.0-doc meshlab geomview librecad
Recommended packages:
xdg-user-dirs
The following packages will be REMOVED:
dvipng feynmf libharfbuzz0a purifyeps texlive-base texlive-binaries texlive-extra-utils
texlive-font-utils texlive-latex-base texlive-latex-base-doc texlive-luatex texlive-metapost
texlive-metapost-doc
The following NEW packages will be installed:
libboost-filesystem1.49.0 libboost-system1.49.0 libharfbuzz0b libqscintilla2-8 openscad-nightly
The following packages will be upgraded:
libglib2.0-0 libglib2.0-bin libglib2.0-dev libharfbuzz-icu0 libpango-1.0-0 libpango1.0-0
libpangocairo-1.0-0 libpangoft2-1.0-0 libpangoxft-1.0-0
9 upgraded, 5 newly installed, 13 to remove and 387 not upgraded.
Need to get 1,202 kB/14.7 MB of archives.

rotate([90, 0, 0])
linear_extrude(height = 10, center = true, convexity = 10, twist = 0)
text("은바탕", font="UnBatang");

text_sample_ko

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Metric bolts and nuts

OpenSCAD ISO metric thread library / functions
http://www.thingiverse.com/thing:311031

I printed M6x12, M10x16, M8x16 bolt and nuts.
Three bolts needed to tap because of tiny blobs. I broke the M6 bolt while tapping it.

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Rough sketch of new belt tensioner

The belt tensioner in Mini Kossel is flawed design. To adjust each belt tension, the top three vertex frames need to be loosen first. And different number of turns of the tensioning bolts creates skewed three axis.

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Initially I played a tension mechanism that uses three bearing, which overly complicated. So I switched to one bearing (idler) mechanism that slides up and down in the rail or channel. Apparently one night after I found identical tensioner design on Reprap forum.

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First layer of the printing object is so critical.

I play in the ten micron (0.01 mm) world. I’m so close to finalize Bulbul Junior 3D Printer but apparently there is one issue I have to solve, which is the Z height changes after few printing session. I suspected slack in GT2 timing belt and put more tension to the timing belt yesterday.

Calibration cubes I’ve printed for a month.
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Printing calibration cubes (20.00 x 20.00 x 20.00) to set the right flow rate.

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Calibration plate for checking level flatness.
134.56 mm in diameter, 5.00 mm in height, 0.02 mm Z offset.

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Printing the calibration plate after G29 Auto level probe, Z offset is 0.00 mm.

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Failed first layer of the calibration plate in second printing.

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Elliptical cylinder as the Groot’s platform

-37.90 mm to 37.90 mm in X and is 75.80 mm wide
-25.40 mm to 25.40 mm in Y and is 50.80 mm deep
0.00 mm to 10.00 mm in Z and is 10.00 mm high

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The Groot in the movie Guardians of the Galaxy
http://www.thingiverse.com/thing:478806

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I apply one layer of this wood glue on the aluminium print bed before printing an object. It’s water soluble.

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Print bed mount

I designed bigger print bed mount to eliminate bed movement while printing and moving.
The diameter of aluminium print bed is 180.00 mm. The diameter of circle that forms the sector of print bed is 180.20 mm.

Aluminium extrusion: 20.00 x 20.00 (mm)
Size: 35.00 x 60.00 x 15.00
Fasteners:
M5x15 Hexa cap screw x2
M5 nut x2
M4x10 Hexa cap screw x1 (Optional)
Download

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Bye bye the old flimsy bed mount!

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A paint scraper I bought at 1,500.00 KRW to clean up job easy after printing objects.

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After three hours of manual calibration of the print bed,
I ran two auto calibrations for 0.05 mm and 0.03 mm.

Current Delta geometry values:
X (Endstop Adj): -4.35
Y (Endstop Adj): -5.40
Z (Endstop Adj): -5.15
P (Z-Probe Offset): X21.00 Y-9.30 Z-6.00
A (Tower A Position Correction): 0.00
B (Tower B Position Correction): 0.00
C (Tower C Position Correction): 0.00
I (Tower A Radius Correction): 0.00
J (Tower B Radius Correction): 0.00
K (Tower C Radius Correction): 0.00
R (Delta Radius): 111.25
D (Diagonal Rod Length): 214.86
H (Z-Height): 207.25

Current Delta geometry values:
X (Endstop Adj): -5.25
Y (Endstop Adj): -5.96
Z (Endstop Adj): -5.66
P (Z-Probe Offset): X21.00 Y-9.30 Z-6.00
A (Tower A Position Correction): -0.19
B (Tower B Position Correction): 0.39
C (Tower C Position Correction): -0.20
I (Tower A Radius Correction): 0.00
J (Tower B Radius Correction): 0.00
K (Tower C Radius Correction): 0.00
R (Delta Radius): 111.37
D (Diagonal Rod Length): 214.86
H (Z-Height): 207.25
>>> G29
SENDING:G29
-0.040 -0.040 -0.040 -0.010 0.020 0.020 0.020
-0.040 -0.040 -0.020 0.010 0.030 0.030 0.030
0.020 0.000 0.010 0.010 0.010 0.000 -0.040
0.000 0.000 0.000 0.000 0.000 -0.010 -0.030
0.020 -0.020 -0.020 -0.000 -0.010 -0.000 -0.030
-0.040 -0.040 -0.020 -0.000 0.030 0.050 0.050
-0.020 -0.020 -0.020 0.020 0.080 0.080 0.080

print_bed_graph_04042015

I think G29 Auto level probe before printing is meaningful anymore.

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