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My Tumblr

  • It does not matter how slow you go so long as you do not stop.
    Wisdom of Confucius

  • photo from Tumblr

    Passing through Times Square by Mareen Fischinger

  • My favorite web site

    Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat.

  • Jack: Hey, you know what sucks?
    Lindsey: vacuums
    Jack: Hey, you know what sucks in a metaphorical sense?
    Lindsey: black holes
    Jack: Hey, you know what just isn't cool?
    Lindsey: lava?

  • Allison Weiss — Fingers Crossed

  • An example post

    Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aliquam nisi lorem, pulvinar id, commodo feugiat, vehicula et, mauris. Aliquam mattis porta urna. Maecenas dui neque, rhoncus sed, vehicula vitae, auctor at, nisi. Aenean id massa ut lacus molestie porta. Curabitur sit amet quam id libero suscipit venenatis.

    • Lorem ipsum dolor sit amet.
    • Consectetuer adipiscing elit.
    • Nam at tortor quis ipsum tempor aliquet.

    Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Suspendisse sed ligula. Sed volutpat odio non turpis gravida luctus. Praesent elit pede, iaculis facilisis, vehicula mattis, tempus non, arcu.

    Donec placerat mauris commodo dolor. Nulla tincidunt. Nulla vitae augue.

    Suspendisse ac pede. Cras tincidunt pretium felis. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Pellentesque porttitor mi id felis. Maecenas nec augue. Praesent a quam pretium leo congue accumsan.

  • Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aliquam nisi lorem, pulvinar id, commodo feugiat, vehicula et, mauris. Aliquam mattis porta urna. Maecenas dui neque, rhoncus sed, vehicula vitae, auctor at, nisi. Aenean id massa ut lacus molestie porta. Curabitur sit amet quam id libero suscipit venenatis.

Decagonal and Quasicrystalline Tilings in Medieval Islamic Architecture

Decagonal and Quasicrystalline Tilings in Medieval Islamic Architecture | peterlu.org

The conventional view holds that girih (geometric star-and-polygon) patterns in medieval Islamic architecture were conceived by their designers as a network of zigzagging lines, where the lines were drafted directly with a straightedge and a compass. We show that by 1200 C.E.

Girih tiles

Girih tiles – Wikipedia

Girih tiles are a set of five tiles that were used in the creation of Islamic geometric patterns using strapwork ( girih) for decoration of buildings in Islamic architecture. They have been used since about the year 1200 and their arrangements found significant improvement starting with the Darb-i Imam shrine in Isfahan in Iran built in 1453.

Tsubaki Abura

Tsubaki Abura – Camellia Oil

Camellia oil is applied to the barengawa (the bamboo sheath on a baren) to keep it supple and prolong its life. The oil may be applied with a saturated pad, cotton ball, or use the palm of your hand. Rub just a drop or two of oil into the sheath, paying attention to the sides as well as the face of the barengawa.

Imported from Japan, our camellia oil comes from camellia japonica seeds. It is cosmetic grade and used in Japan as a hair and skin moisturizer, so it is good for your skin as well the barengawa.

The oil will also protect cutting tools from rust. Apply a small amount to the steel blade after sharpening it on water stones.

Recipe for Pure Rice Starch Paste

This neutral pH rice starch powder is made from glutinous rice, so mixing and
cooking it on the stove is not necessary. If your tap water has a high mineral content, use distilled water instead.

1. Place 3 tablespoons of rice starch powder in 1 cup of boiling water.
2. Stir briskly with a wire whisk until smooth. If there are lumps left, pour the hot mixture through a strainer and discard the lumps.
3. Cool before using. The rice paste will thicken as it cools. This recipe will produce a paste that is about the consistency of heavy cream or yogurt.

For a thicker paste, use 4 tablespoons of rice starch; for a thinner paste, use 2 tablespoons.

If you prefer to cook the paste, this recipe is from The Art & Craft of Woodblock Printmaking.

1. Mix 2 tablespoons of rice starch with 5 dl (3½ tablespoons) cold water
2. Stir until smooth and milky
3. Bring 150ml (2/3 cup) of water almost to the boil
4. Add the paste mix in a smooth ribbon while stirring
5. Bring to a boil and keep stirring constantly until the mix goes translucent (about five minutes)
6. Cool, stirring from time to time

The mixture will thicken as it cools. If it is too thick, thin with water. If it is too thin, make a new mixture
but this time make it extra thick so you can add it to the first mixture. Combining the two will give the
optimal thickness.

Nori – Rice Starch Paste


Nori is very important in the Japanese style of printmaking. It works as a dispersing agent to give the ink body so it will spread evenly over the block. Ink without nori can look speckled when it is printed, often an unwanted effect, while ink with nori prints more uniformly. Traditionally, it is also used to paste the original drawing to the block.

Nori can be used for chine collé, book repair, and everyday paper pasting jobs. It is smooth, has a pleasant scent, and will not stain. Water reversible, nori is acid free, strong, and because it contains a very tiny amount of formalin, it does not spoil.

If you prefer to make your own rice paste, we also carry Pure Rice Starch.

seen at McClain´s Printmaking Supplies

kento registration

The kento is a simple device by means of which the printer insures the register of the picture throughout the printing process. It has been employed for several centuries, and experience has proved it to be the best means for the purpose. The principle is to maintain with absolute exactness the width of the margin of every requisite block by means of two small projections, the kagi (key) and the hikitsuke (draw stop), which are cut directly on the block, as shown in Figure 1. These guides cut on the key block will be printed on the kyogo (proofs pulled from the key block) and therefore copies on every color block, keeping the margin the same width as that of the key block. The printer positions his paper so that its edges coincide with these guides during printing. The kagi is a right-angled guide at the lower right-hand corner of the block; the hikitsuke, a straight-line guide…at a short distance from the lower left-hand corner. To cut these guides, the carver uses the kento-nomi,(a 15mm chisel) the edge of which is strongly made with a wider angle and is perfectly straight. The kento-nomi is held by the grip in the right hand, resting upright on the board with its edge exactly at the line to be cut, in such a manner that the flat side of the tools is vertical to the surface of the board (Figure 2). Then it is pressed down to make a cut about one-eighteenth of an inch deep. After the necessary lines have been cut in this way, the space must be cleared with an aisuki(bull-nose chisel) of large size. The clearing must be very shallow and must produce a flat and smooth surface in order to facilitate the fitting of the paper during printing. The depth required is two to three times the thickness of the paper to be used. In making the kagi, the cleared part must slope very slightly toward the point of the right-angled corner. The hikitsuke is left in the form of a sort of step, the top of which is cut in a straight line. The detail of these two guides can be seen in Figure 3a and 3b.

Re-printed from Japanese Print-Making by Toshi Yoshida and Rei Yuki, c. 1966


Products – Charmed Labs

Products – Charmed Labs

New! Pixy for LEGO Mindstorms Fast vision sensor for LEGO robotics Easily “teach” Pixy objects to track Connects directly to NXT or EV3 brick Pixy (CMUcam5) Fast vision sensor for robotics Easily “teach” Pixy objects to track Connects directly to Arduino Pan/Tilt Kit for Pixy Dual servos provide X-Y movement Great “Hello world” demo for …

mDrawbot Kit – Open-source Arduino Robot Platform

mDrawbot Kit

Based on Makeblock open platform, mDrawBot is a transformable drawing robot kit that integrates mechanics, electronics, software, and art. It can be assembled into four forms: mScara(Cylindrical Coordinates Robotic Arm), mSpider(Wall-Drawing Machine), mEggBot(Egg-Painting Robot), mCar(Drawing Car).

Based on Makeblock open platform, mDrawBot is a transformable drawing robot kit that integrates mechanics and electronics via the easy-to-use software mDraw.

mScara (Cylindrical Coordinates Robotic Arm)
mSpider (Wall-Drawing Machine)
mEggBot (Egg-Painting Robot)
mCar (Drawing Car).


Acronym for computer-aided design

computer-aided manufacturing

computer numerical control: automated operation of a machine by a computer program.


DRV8825 Stepper Motor Driver Module

The DRV8825 stepper motor driver carrier is a breakout board for TI’s DRV8825 microstepping bipolar stepper motor driver. The module has a pinout and interface that are nearly identical to those of our A4988 stepper motor driver module, so it can be used as a higher-performance drop-in replacement for those boards in many applications. The DRV8825 features adjustable current limiting, overcurrent and overtemperature protection, and six microstep resolutions (down to 1/32-step). It operates from 8.2 – 45 V and can deliver up to approximately 1.5 A per phase without a heat sink or forced air flow.
DRV8825 allows higher resolutions by allowing intermediate step locations, which are achieved by energizing the coils with intermediate current levels. The resolution (step size) selector inputs (MODE0, MODE1, and MODE2) enable selection from the six step resolutions according to the table below:
MODE0 MODE1 MODE2 Microstep Resolution
Low Low Low Full step
High Low Low Half step
Low High Low 1/4 step
High High Low 1/8 step
Low Low High 1/16 step
High Low High 1/32 step
Low High High 1/32 step
High High High 1/32 step
    There are 2 wiring modes for connecting a microcontroller to the DRV8825 module:


  • Simple step and direction control interface
  • Six different step resolutions: full-step, half-step, 1/4-step, 1/8-step, 1/16-step, and 1/32-step
  • Adjustable current control lets you set the maximum current output with a potentiometer, which lets you use voltages above your stepper motor’s rated voltage to achieve higher step rates
  • Intelligent chopping control that automatically selects the correct current decay mode (fast decay or slow decay)
  • 45 V maximum supply voltage
  • Built-in regulator (no external logic voltage supply needed)
  • Can interface directly with 3.3 V and 5 V systems
  • Over-temperature thermal shutdown, over-current shutdown, and under-voltage lockout
  • Short-to-ground and shorted-load protection


5V Stepper Motor 28BYJ-48Drive Test Module Board ULN2003 5Line 4Phase Kit

5V Stepper Motor 28BYJ-48 With Drive Test Module Board ULN2003 5Line 4Phase Kit | eBay

5 Line 4 phase can be driven by ordinary uln2003 chip can also be connected in phase 2 development board used for. Stepper motor driver board with ULN2003. 1 ULN2003 Drive Test Module Board. This board motor kit supports you to use a direct plug and make it easy to use stepper motor used in the development board.

CAM-GCode software

G-code generators

A) grbl-controller 3.0
Grbl Controller sends GCode to CNC machines. Version 3.0 is has been optimized for the Arduino to control Grbl shields. Grbl Controller can use the QextSerialPort library to simplify choosing the correct USB serial port.

B) Makercam
MakerCAM is a web based CAM program. Simple by design, MakerCAM allows you to produce toolpaths for 3-axis CNC machines that accept standard RS274D GCode.
link: Getting started tutorial
link: about makercam

C) Easy cnc
The goal of the project is the realization of a modular firmware that allows to control a CNC machine with different utensils.

D) cnc-masteryou
A small program to quickly generate GCode. It can generate circular pockets, square pockets, etc. Now you can generate a simple program from DXF.
Use the tab “Cutting a path” or “Array of elements”. Added engraving by DXF file.

E) gcodetools – inkscape plugin

F) JSCUT – a cam in your browser

G) benbox


G-code senders

A) Universal g-code sender
AA) Universal g-code sender SHAPEOKO

B)  Chilipeppr – read the github information


GCode Ripper Wrap GCode for 4th Axis or do Engraving on Irregular Surfaces after Probing
LinuxCNC / EMC2 Free CNC Control Software
Jedicut CNC Foam Cutting
Ace Converter DXF to G-Code
2linc Engraving Software: Light Version Engraving Software
and fonts
DeskEngrave Engraving Software
Image to G-Code Image or bitmap to g-code
MaxCut Nesting


grbl on python: pyGerber2Gcode
3 x 4 Pin Dupont Female Connectors
GRBL firmware http://www.ebay.com/itm/Arduino-CNC-Shield-V3-10-G…

Pi Cap – Bare Conductive

The Pi Cap adds precise capacitive touch, proximity sensing and high quality audio to your Raspberry Pi.

Connect your Pi project to the physical world. Create sensors by connecting Electric Paint or anything conductive  to one of the Pi Cap’s 12 electrodes to control audio, video or connect to the internet. Make a MIDI piano, an  interactive wall, a proximity sensor — you decide. Our Raspbian package contains code examples for C++, Python  and Node.js.

• Capacitive touch and distance sensing
• High quality audio output
• Tutorials to help you get started
• User-­programmable RGB LED
• Multi function button
• Prototyping area with GPIO breakout
• Compatible with Raspberry Pi A+, B+, Zero (or any Pi with  40 pin GPIO connector)
• Powerful C++, Python and Node.js libraries and examples

Works with:
Crocodile clips, copper tape,  solder and e­‐textiles. Use with Electric Paint to design your own sensors

PI 123 instructions

16 Channel PWM Expansion Board

Control Servos + PWM devices using this 16 channel PWM Expansion Board. PCA9685

When you run out of PWM Arduino-pins or are on a Raspberry Pi that doesn’t have PWM capability. With this PWM Expansion Board you can control up to 16 PWM driven devices from via 2 I2C pins. Can also be daisy-chained to give you up to 992 PWM outputs.


  • I2C controlled PWM/Servo driver board
  • Clock on board
  • Operating Voltage: 3.3V – 6V
  • 6 I2C Address Select Pins
  • Max Daisy-chaining: 62 boards for a total of 992 PWM outputs
  • Max PWM frequency: 1.6 kHz
  • Resolution: 12 bit
  • Configurable Output (push-pull or open-drain)
  • Output Enable (OE) allows you to turn off all outputs at once
  • Onboard Features:
    • Polarity Protection
    • Power Indicator LED
    • Optional capacitor solder point for smoothing
      • Address Select Jumpers

GRBL workflow – Arduino

INSTALL WORKFLOW using an arduino uno and an arduino cnc shield:

1) Grbl is a motion control GCode Interpreter. The controller is written in highly optimized C to achieve precise timing and asynchronous operation. It is able to maintain up to 30kHz of stable, jitter free control pulses.
download GRBL 1.1 here

2) Flash the file to the arduino in various ways:
compile in the Arduino IDE
— download  the Arduino IDE for mac – pc – linux


get inspired from some nice examples from the original author


Protoneer directions for customized GRBL




Stepper Motor Basics

A stepper motor is a brushless, synchronous electric motor that converts digital pulses into mechanical shaft rotations. Each rotation of a stepper motor is divided into a set number of steps, sometimes as many as 200 steps. The stepper motor must be sent a separate pulse for each step. The stepper motor can only receive one pulse and take one step at a time and each step must be the same length. Since each pulse results in the motor rotating a precise angle — typically 1.8 degrees — you can precisely control the position of the stepper motor without any feedback mechanism.

As the digital pulses from the controller increase in frequency, the stepping movement converts into a continuous rotation with the velocity of the rotation directly proportional to the frequency of the control pulses. Stepper motors are widely used because of their low cost, high reliability, and high torque at low speeds. Their rugged construction enables you to use stepper motors in a wide environmental range.

Advantages of Using Stepper Motors

  • A wide range of rotational speeds can be utilized since the speed of a step motor is proportional to the frequency of the input pulses from your controller.
  • Precise open-loop positional control is possible with a stepper motor without any feedback mechanism.
  • Very low speed rotation is possible with a load that is coupled directly to the shaft of the stepper motor.
  • A stepper motor is quite reliable because there are no contact brushes. Generally, the life of a stepper motor is determined by the life of the stepper motor bearing.
  • A stepper motor is very good at starting, stopping, and reversing direction.
  • A stepper motor provides precise positioning and repeatability of movement.
  • An energized stepper motor maintains full torque at standstill position.

Types of Stepper Motors

There are three kinds of step motors: permanent magnet, hybrid, and variable reluctance. Hyrbrid step motors offer the most versatility and combine the best characteristics of variable reluctance and permanent magnet stepper motors. Hybrid stepper motors are constructed with multi-toothed stator poles and a permanent magnet rotor. A standard hybrid stepper motor has 200 rotor teeth and rotates 1.8 degrees per step. Hybrid stepper motors provide high static and dynamic torque and they run at very high step rates. Applications for hybrid stepper motors include computer disk drives and cd players. Hybrid stepper motors are also widely used in industrial and scientific applications. Hybrid step motors are used in robotics, motion control, automated wire cutting, and even in high-speed fluid dispensers.

Step Modes

Stepper motor “step modes” include full step, half step, and microstep. The type of step is dependent on the stepper motor driver controlling the stepper motor. Many stepper motor controllers are multi-step capable (usually adjusted by switch setting).

Full Step

Standard hybrid stepping motors have 200 full steps per revolution. If you divide the 200 steps into the 360 degrees of rotation you get 200 1.8 degree steps. Normally this is achieved by energizing both windings while alternately reversing the current, meaning one pulse from the driver is equal to one full step on the step motor.

Half Step

Half Step means that the stepping motor is rotating at 400 steps per revolution (0.9 degree steps x 400 = 360 degrees). First one winding is energized and then two windings are alternately energized. This will cause the rotor of the stepping motor to move at half the distance (0.9 degrees). In half-step mode, a typical stepper motor provides about 30% less torque, but it provides a smoother motion than it would in full-step mode.


Microstepping is a relatively new stepping motor system. Microstepping energizes the stepper motor winding in a manner that further subdivides the number of positions between poles. Some microstepping controllers are capable of dividing a full step (1.8 deg) into 256 microsteps. This would result in 51,200 steps in one revolution (.007 deg/step). Microstepping is usually applied to applications that require accurate positioning and smoother motion over a broad range of speeds. As in the half-step mode, microstepping reduces torque by about 30% compared to full-step mode.

Linear Motion Control

Stepping motors are often used for linear motion control using a lead screw or worm gear drive. The pitch of the lead screw controls the amount of linear distance traveled in one revolution of the screw. So, if the lead is equal to one inch per revolution and there are 200 full steps in one revolution of the stepping motor shaft, then the resolution of the lead screw system would be 0.005 inches per step. Finer resolutions can be attained using the step motor and stepping motor driver combination in microstep mode.

Series and Parallel Connection

A stepper motor can be connected either in series or parallel mode. A series connection system results in high inductance and consequently greater torque at low speeds. A parallel connection method will reduce the inductance resulting in increased torque at higher speeds

Stepper Motor Drivers Overview

The stepper motor is controlled by a stepper motor driver board. The stepper motor driver receives step and direction signals from a control system, typically a computer, and converts them into electronic signals which run the stepper motor. One pulse is needed for every step of the stepper motor shaft. In full-step mode, assuming you’re using a standard 200 step motor, 200 steps or pulses completes one revolution of the stepping motor shaft. The speed and rotation of the stepper motor shaft is directly proportional to the frequency of the pulse.

The speed and torque of a stepper motor is determined by the flow of current from the stepping motor driver to the stepping motor winding. Inductance reduces the flow or limits the time it takes for the current to energize the winding. Most stepper motor driver circuits are designed to supply a greater amount of voltage than the stepper motor’s rated voltage. The higher the output voltage from the stepper motor driver, the higher the level of torque versus speed. In general, the stepper motor driver’s output voltage, also known as bus voltage, should be rated five to ten times higher than the stepper motor’s voltage rating. In order to protect the stepping motor, the step motor controller’s current should be limited to the step motor current rating.

Controller (Indexer) Overview

The stepper motor controller, also known as an indexer, provides step and direction outputs to the stepping motor driver. Most applications require that the controller manages other functions as well such as acceleration, deceleration, steps per second, and distance. The controller (indexer) can also connect to and control other external signals as defined by the project.

Communications to the stepping motor system indexer is usually provided through an RS-232 or RS-485 port. In either configuration, the indexer can receive high level commands from a host computer and supply the appropriate step and direction pulses to the stepper motor driver.

The stepping motor system indexer includes auxiliary input/output for monitoring from external sources such as Go, Home, Jog, or Limit switch.

see original

Nema 17 Stepper Motors

NEMA 17 – 12V – four-phase unipolar permanent-magnet stepper-motor
1.8° full step – 200 steps-per-revolution
0.9° half-step – 400 steps-per-revolution

NEMA chose to label stepper motors (e.g. “NEMA 17”) with the size of their faceplate in tenth of inches. So a “NEMA 17” has a 1.7 inch by 1.7 inch faceplate. By standardizing the stepper motors (the faceplates, flanges and screw holes), you know ahead of time that one NEMA 17 motor will fit into the mounts of another NEMA 17 without having to redesign anything. This makes swapping components easier.

1.5 kg-cm 6 Wire NEMA 17 Stepper Motor – Item no. 42BYGH34-04
12VDC, Rated current 1.3A, 500rpm, Torque 0.26NM, size: 42x42x34mm

17HS1352-P4130 – hybrid
2.2 kg-cm 6 Wire NEMA 17 Stepper Motor
12-24VDC, Rated current 1.33A, 500rpm, Torque 0.26NM, size: 42x42x34mm

1.7A – 1.8degrees

42BYGHW609D4P1 Stepper Motor (Makeblock 81042)
STEP ANGLE : 1.8+-5%°/STEP



Grbl is a no-compromise, high performance, low cost alternative to parallel-port-based motion control for CNC milling. It will run on a vanilla Arduino (Duemillanove/Uno) as long as it sports an Atmega 328.

The controller is written in highly optimized C utilizing every clever feature of the AVR-chips to achieve precise timing and asynchronous operation. It is able to maintain up to 30kHz of stable, jitter free control pulses.

It accepts standards-compliant g-code and has been tested with the output of several CAM tools with no problems. Arcs, circles and helical motion are fully supported, as well as, all other primary g-code commands. Macro functions, variables, and most canned cycles are not supported, but we think GUIs can do a much better job at translating them into straight g-code anyhow.

Grbl includes full acceleration management with look ahead. That means the controller will look up to 18 motions into the future and plan its velocities ahead to deliver smooth acceleration and jerk-free cornering.

download at github


Pololu A4988 compatible stepper drivers. (A4988, DRV8825 and others) 

The A4988 is a microstepping driver for controlling bipolar stepper motors which has built-in translator for easy operation.







Microstepping can divide a motor’s basic step up to 256 times. Microstepping improves low speed smoothness and minimizes low speed resonance effects.
Microstepping produces roughly 30% less torque than dual phase full stepping


Arduino CNC Shield V3


  • GRBL 0.8c compatible. (Open source firmware that runs on an Arduino UNO that turns G-code commands into stepper signals https://github.com/grbl/grbl)
  • 4-Axis support (X, Y, Z , A-Can duplicate X,Y,Z or do a full 4th axis with custom firmware using pins D12 and D13)
  • 2 x End stops for each axis (6 in total)
  • Spindle enable and direction
  • Coolant enable
  • Uses removable Pololu A4988 compatible stepper drivers. (or DRV8825)
  • Jumpers to set the Micro-Stepping for the stepper drivers. (max 1/16)
    (The DRV8825 board can do up to 1/32 micro-stepping)
  • Stepper Motors can be connected with 4 pin molex connectors.
  • Runs on 12-36V DC. (Only the Pololu DRV8825 can handle up to 36V)

Using two jumpers the 4th axis can be configured to clone the X or Y or Z axis. It can also run as an individual axis by using Digital Pin 12 for Stepping signal and Digital Pin 13 as direction signal. (GRBL only supports 3 axis’s at the moment)

Clone X-Axis to the 4th stepper driver(Marked as A)Arduino-CNC-Shield-V3-4th Clone X-Axis

Clone Y-Axis to the 4th stepper driver(Marked as A)Arduino-CNC-Shield-V3-4th Clone Y-Axis

Clone Z-Axis to the 4th stepper driver(Marked as A)Arduino-CNC-Shield-V3-4th Clone Z-Axis

Use D12 and D13 to drive the 4th stepper driver(Marked as A)Arduino-CNC-Shield-V3-4th D12-D13

End Stop Configuration

By default GRBL is configured to trigger an alert if an end-stop goes low(Gets grounded). On the forums this has been much debated and some people requested to have active High end-stops. The jumpers in the picture provides the option to do both. (To run with default setting on GRBL the jumper need to be connected like the left shield in the image below)(This Jumper was only introduced in Version 3.02)
End-stop Configuration Active LOWorHIGH

End-stop switches are standard “always open” switches. An End-stop gets activated when the end-stop pin connects to ground(When setup with default GRBL settings).

Configuring Micro Stepping for Each Axis

Each axis has 3 jumpers that can be set to configure the micro stepping for the axis.


In the tables below High indicates that a Jumper is insert and Low indicates that no jumper is inserted.

dfrobot LCD 16×2 Shield


  • Operating Voltage: 5V
  • 5 Push buttons to supply a custom menu control panel
  • RST button for resetting arduino program
  • Integrate a potentiometer for adjusting the backlight
  • Pin used:
    • D4-D7    -> LCD Data transmission
    • D8       -> Register Select
    • D9       -> Enable pin
    • D10      -> Backlight control
  • APC&BT pin header for connecting wireless devices, directly compatible with:
  • Expanded available I/O pins
  • Expanded Analog Pinout with standard DFRobot configuration for fast sensor extension
  • Dimension: 80 x 58 mm (3.15x 2.28 in)

(SKU: DFR0009)


brew install python
brew link python
brew install python3
brew link python3
brew doctor


rm -rf mydir

Zelle graphics.py

fd forward
lt left
rr right
bk back

pu pen up
pd pen down

repeat 4 [fd 90 lr 90]

0 black
1 blue
2 green
3 cyan
4 red
5 magenta
6 yellow?
7 white
8 brown
9 beige
10 bright green
11 dark blue
12 salmon
13 blueish
14 orange
15 grey




POTS (That’s short for Print Out TitleS.)


brew install node
npm install -g npm@latest
npm i -g n && n latest
(Node package manager)

(nvm install node –reinstall-packages-from=node)

brew update && brew upgrade node && npm install -g npm

1. sudo npm cache clean -f ———— (force) clear you npm cache
2. sudo npm install -g n ———install n (this might take a while)
3. sudo n stable ——— upgrade to lastest version
node -v
You could install nvm and have multiple versions of Node.js installed.
curl https://raw.github.com/creationix/nvm/master/install.sh | sh
source ~/.nvm/nvm.sh
and then run:
nvm install 0.8.22 #(or whatever version of Node.js you want)
you can see what versions you have installed with :
nvm list
and you can change between versions with:
nvm use 0.8.22
The great thing about using NVM is that you can test different versions alongside one another. If different apps require different versions of Node.js, you can run them both.

MicroPython – ESP8266

3. The internal filesystem – MicroPython 1.9.2 documentation

If your devices has 1Mbyte or more of storage then it will be set up (upon first boot) to contain a filesystem. This filesystem uses the FAT format and is stored in the flash after the MicroPython firmware.

ls /dev/tty.*
ls /dev/cu.*
ls /dev/{tty,cu}.*

pip install esptool
esptool.py –port /dev/tty.wchusbserialfd120 erase_flash
esptool.py –port /dev/tty.wchusbserialfa130 erase_flash

esptool.py –port /dev/tty.wchusbserialfd120 –baud 460800 write_flash –flash_size=detect 0 esp8266-20170823-v1.9.2.bin
esptool.py –port /dev/tty.wchusbserialfa130 –baud 460800 write_flash –flash_size=detect 0 esp8266-20170904-v1.9.2-41-g9950865c.bin

boot.py – main-py

1: terminal:
screen /dev/cu.wchusbserialfa130 115200 (WEMOS MINI)
screen /dev/cu.wchusbserialfd120 115200

(initialize:) import webrepl_setup
(assign password) allow acces

2: webrepl.html


>>> print(‘hello esp8266!’)

>>> import machine
>>> pin = machine.Pin(2, machine.Pin.OUT)
>>> pin.on()
>>> pin.off()

>>> def toggle(p):
… p.value(not p.value())
(enter 3 times exits)

>>> import time
>>> while True:
… toggle(pin)
… time.sleep_ms(500)

paste mode; Ctrl-C to cancel, Ctrl-D to finish

>>> f = open(‘data.txt’, ‘w’)
>>> f.write(‘some data’)
>>> f.close()

>>> f = open(‘data.txt’)
>>> f.read()
‘some data’
>>> f.close()

>>> import os


arduino board som lader dig kommunikere via din Smartphone (ios & android)


Tetrahedron Cube Octahedron Dodecahedron Icosahedron
Four faces Six faces Eight faces Twelve faces Twenty faces
Polyhedron Vertices Edges Faces Schläfli symbol Vertex configuration
tetrahedron Tetrahedron 4 6 4 {3, 3} 3.3.3
cube Hexahedron (cube) 8 12 6 {4, 3} 4.4.4
octahedron Octahedron 6 12 8 {3, 4}
dodecahedron Dodecahedron 20 30 12 {5, 3} 5.5.5
icosahedron Icosahedron 12 30 20 {3, 5}

Cartesian coordinates[edit]

For Platonic solids centered at the origin, simple Cartesian coordinates are given below. The Greek letter φ is used to represent the golden ratio 1 + √5/2.

Cartesian coordinates
Figure Tetrahedron Octahedron Cube Icosahedron Dodecahedron
Faces 4 8 6 20 12
Vertices 4 6 (2 × 3) 8 12 (4 × 3) 20 (8 + 4 × 3)
1 2 1 2 1 2
Coordinates (1, 1, 1)
(1, −1, −1)
(−1, 1, −1)
(−1, −1, 1)
(−1, −1, −1)
(−1, 1, 1)
(1, −1, 1)
(1, 1, −1)
(±1, 0, 0)
(0, ±1, 0)
(0, 0, ±1)
(±1, ±1, ±1) (0, ±1, ±φ)
(±1, ±φ, 0)
φ, 0, ±1)
(0, ±φ, ±1)
φ, ±1, 0)
(±1, 0, ±φ)
(±1, ±1, ±1)
(0, ±1/φ, ±φ)
1/φ, ±φ, 0)
φ, 0, ±1/φ)
(±1, ±1, ±1)
(0, ±φ, ±1/φ)
φ, ±1/φ, 0)
1/φ, 0, ±φ)
Image CubeAndStel.svg Dual Cube-Octahedron.svg Icosahedron-golden-rectangles.svg Cube in dodecahedron.png






The three regular tessellations of the plane are closely related to the Platonic solids. Indeed, one can view the Platonic solids as regular tessellations of the sphere. This is done by projecting each solid onto a concentric sphere. The faces project onto regular spherical polygons which exactly cover the sphere. There are three possibilities:

The three regular tilings

Uniform tiling 44-t0.svg


Uniform tiling 63-t2.png


Uniform tiling 63-t0.png

{4, 4}

Vertex type 4-4-4-4.svg

(t=1, e=1)1-uniform n5.svg

{3, 6}

Vertex type 3-3-3-3-3-3.svg

(t=1, e=1)

1-uniform n11.svg

{6, 3)

Vertex type 6-6-6.svg

(t=1, e=1)

1-uniform n1.svg




Polygon nets around a vertex
Defect 180°
Defect 120°
Defect 60°
Defect 0°
Defect 90°
Square tiling vertfig.png
Defect 0°
Pentagon net.png
Defect 36°
Hexagonal tiling vertfig.png
Defect 0°
A vertex needs at least 3 faces, and an angle defect.
A 0° angle defect will fill the Euclidean plane with a regular tiling.
By Descartes’ theorem, the number of vertices is 720°/defect.










The 19th century gum bichromate process in 21st century concept and techniques « Gum Bichromates « Formulas And How-To « AlternativePhotography.com

Christina Z. Anderson gives us the “why and how” of the gum process, including making negatives.Share this:Click to email this to a friend (Opens in new window)Click to print (Opens in n…

Source: The 19th century gum bichromate process in 21st century concept and techniques « Gum Bichromates « Formulas And How-To « AlternativePhotography.com

cyanotype QUICKIE

NB: forbered blandingerne mindst 24 timer før de skal anvendes.
– Opbevar begge opløsninger i brune lufttætte flasker
– Markér flaskerne med navn, dato og blandingsforhold.

Blanding A: Ammoniumjerncitrat
100 ml (50 ml) distilleret vand ~21 °C
20 g (10 g) Ferric ammonium citrate (green)

Blanding B:  Blodludssalt, rødt
100 ml (50 ml) distilleret water ~21 °C
8 g (4 g) Potassium ferricyanide

Cyanotype maskeringer

til inspiration – det praktiske er ikke løst endnu

Cyanotype toning: the basics « MP Photography

“No one but a vandal would print a landscape in red, or in cyanotype.” (Peter Henry Emerson: Naturalistic Photography for Students of the Art, London: Sampson Low, Marston, Searle and Rivington, 1889) Citation courtesy of Luminous Lint/Mike Ware.

I happen to agree with Mr. Emerson so I tone pretty much all of my cyanotypes.  I have several posts about different toners and how they (generally) look, but this post will go over the basic process of toning and try to troubleshoot a few common problems.

Toning a cyanotype involves two basic steps: a bleach phase, and a toning phase.  Every toner I know of contains some type of tannin in it: tannin chemically binds to the iron in the emulsion and changes the color.  If I understand this process correctly, it produces a form of gallic acid – used in dyes and inks, especially medieval ones.  I’ve read that gallic acid is normally corrosive, but I’ve never found this to be the case with toned cyanotypes.

If you’re concerned about the archival quality of your toned cyanotypes, Dr. Mike Ware (inventor of the ”New” cyanotype process) has said that his family photo albums contain what he’s pretty certain are toned cyanotypes – because they look very similar to other alternative processes it’s easy to confuse with Van Dyke prints or Kallitype prints.  I’ve personally never had issues with mine – I’ll get back to you in some 20 years or so and see if that’s still the case.

Keep in mind that toners are funny things – you can mix and match things, you can vary the sequence of bleach and toner and get different results.  I have a lot of good results with simply leaving the prints in the toner for long periods of time without bleaching at all.  Take things one at a time – don’t try to tone or bleach multiple prints together.  Experiment and have fun with it!  Just remember that the key to a successful toned print is to wash well between steps.

1. Toning Preparations:

Before you start your toning, always:

  • Age your prints at least 24 hours for the emulsion to harden.
  • Pre-wet your prints in filtered water to allow the solutions to penetrate the paper fibers evenly.
  • It’s a good idea to have multiple prints – toning is fickle, you never know what you’re going to get.
  • Plan to leave the print face down for long periods of toning, or plan enough time to “babysit” the print – agitate it while face up in the toner.

2. The Bleach Phase:

Bleaching is a tricky thing.  The purpose of bleaching is to help break down the iron a little so that the tannin in the toner can “grab on” easily.  If your water is heavily chlorinated, you may not even need to bleach your prints.

How much you bleach really depends on how you coat, how much emulsion is on the paper, and what toner you’re using.  If you bleach too far, you lose shadow density.  If you bleach too little, your shadows will stay a stubborn blue shade while your highlights cooperate.

Bleach types: the most common form of bleach solution is Sodium Carbonate.  That’s Washing Soda, usually found in your grocery store’s cleaner aisle, or at a photography chemical supply store.   Don’t confuse this with Sodium Bicarbonate – baking soda – it won’t react the same way.

Other types of bleach that I’ve used are Ammonia and regular chlorine bleach.  Ammonia stinks, horribly, and usually produces a browner image.  Chlorinated bleach destroys paper fibers and is better left to your laundry.

My typical bleach solution is about 1-2 teaspoons of Sodium Carbonate combined with 1 Liter of water.  If your print turns a bright purple the second you place it in the solution, it’s too strong.   Play with the solution until you’re comfortable with the rate of bleaching.  As you practice bleaching, you’ll notice that it’s a good idea to yank the print out a few seconds before you think it’s ready – the print will continue to bleach a bit while starting to rinse.

Always rinse the print well in running water between the bleach phase and the toning phase.

3. The Toning Phase:

All cyanotype toners are pretty much variations on a black/brown/purple theme.  Certain toners are more efficient and stain less, while other toners produce a wider range of possible colors.  Keep in mind that all toners will stain your paper base a little despite your best efforts.  (please note that the following links lead to blog post about the toners, or examples of the toner shade.)

Tea toner:  Most tea toners that I use are brewed for about 10 minutes in  25o mL of hot water, then added to a 1.5 Liter of room temperature filtered water.  I use about 8-10 small tea bags, not a very accurate measurement!  Every type of tea has a different quality or color to it – make sure that you use teas with tannin in them like black tea or green tea – white tea, red tea, and most herbal teas don’t have enough tannin to do anything to your print.

Green tea produces an eggplant/black shadow, and is so mild that it doesn’t stain the paper base too badly.  If you’re toning a high key image, green tea will sometimes produce a really cool pink highlight.  It has a tendency to split tone for me because of my double coat of emulsion.

Black tea will stain your paper the most, but it produces a lovely warm black/brown shade that’s nearly impossible to get anywhere else.  I generally use a Lipton tea product for iced tea, but any black tea will work.  If you want an easy split toner with warm highlights and blue shadows, black tea is the fastest way to get it.

Earl Grey tea: avoid this one – it has a lot of oils in it that can damage your print.

Tea toners work really well with a minimum of bleaching, but they do require a longer immersion for the iron to shift.  I normally tone prints in tea for about 2 hours, but depending on the print, it’s taken up to 8 hours.  Some people suggest that tea toners should be hot for a faster toner – in my experience that shaves about 30 minutes off the toning time, and stains the paper much worse.   It’s a good idea to let the print sit in clean filtered water for about 10 minutes before the final rinse to help remove some of the excess tannin.  All tea toners should be used freshly brewed – they lose potency after a day and should not be reused.

Tannic Acid Toner:  This stuff is a royal pain to work with.  It can produce the closest thing to a true black, but it’s far more likely to screw up, or produce a weird purply brown shade.  It has the widest range of color tones that I’ve seen in a toner, but you have absolutely no control over what you get.  Be extremely careful how much bleaching you do, because this toner is totally unforgiving if you go the slightest bit too far.

Done well, this toner produces the least paper staining – however, I’ve run into some chemical issues that I don’t quite understand that leave my paper the shade of cardboard.  (I’ve narrowed it down to interactions with the tap water, or the age of the toner.)

Tannic Acid is produced from wood chips, and is extremely hard to mix into a solution.  It’s a gummy mess.  Because of this it’s difficult to estimate how much I use, but generally about a Tablespoon mixed into a Liter of water is a good place to start (and then remove the gummy bits.)  A good tannic acid solution should be almost clear, and will take a minute of sitting in filtered water to fully tone out.  Toning times for tannic acid are usually quite short.

If mixed with distilled water, tannic acid toner will last for a few weeks/months.  A little mold is normal, just filter the solution every time you use it.  Once the solution starts turning a dark brown or granulating (tiny little granules appear – not sure what they are) it’s time to start fresh.  Tannic acid is also quite expensive, and only available at a photography chemical supply store like Photographer’s Formulary.

Coffea TonerI love coffee toner.  It’s a cold toner, as opposed to the warmer tea shades, and it leaves the paper pretty close to the original color.  It will still stain, just not as badly as tea.  Coffee doesn’t produce a true black, but more of a blue/black like a blackbird’s feathers.  The highlights will stay pretty clean so make sure your contrast is good and your highlights aren’t blown out.

I generally use the cheapest instant coffee I can find – about 4-5 heaping tablespoons of instant coffee dissolved into 250 mL of hot water, then added to 1.5 Liters filtered room temperature water.  I’ve read that other people have great success re-brewing used coffee grounds – since I don’t drink coffee I can’t exactly test this.

Coffee toner doesn’t seem to take quite as long as tea toner, but expect at least an hour of toning, perhaps more.  Again, it’s a good idea to let the print rest in a water bath before the final rinse.

Wine TanninThis is my new favorite toner, and I don’t have that much experience with it yet.  So far, it produces a nice dark shadow and a brown/tan highlight on a fairly regular basis.  It can be rather fickle if you keep the solution for a long period of time, so I suggest storing this toner no more than a month.

Wine tannin is basically the same thing as tannic acid, but produced from a different source.  It’s designed to use in microbrewing so it mixes into solution a lot easier.  It leaves the paper almost paper white, producing almost no staining.  It’s slightly cheaper than tannic acid, but since it requires more to produce the same effect – half an ounce of wine tannin mixed into 1 L of water – the price is probably pretty close.  I use the powdered version, but some stores have a liquid solution available.

Wine tannin has a tendency to put any coating discrepancies on display.  Unless I use the Christopher James variation listed in the link (toss the print into the tannin instead of bleaching first) I lose some of my highlight detail.  Like the tannic acid, it works pretty quickly.  Wine tannin also has a weird chemical reaction that can turn my paper to a cardboard brown, requiring a water bath before the final rinse.


1. My print looks faded!  What happened?  You probably bleached the print too far.  Try test strips in varying times to get a better idea of what works – the ideal is to tone your shadows dark without losing highlight details.  Usually this means bleaching until the shadows are a dark purple and the highlights are slightly yellow.

2. I left the print in the toner forever, but it’s still blue!  What now?  Rinse the print for at least 5 minutes and go back to the bleach bath.  After bleaching again – just a little, rinse it again for 5 minutes and put it back in the toner.  Your initial bleach probably didn’t break the iron down enough.

3. The print toned nicely, but now that it’s dry I hate it!  Why does it look so flat?  I don’t know why, but that’s normal for a toned cyanotype.  Try brushing a diluted solution of acrylic gloss medium onto the print to bring back the shadow depth and give the surface a little shine.  It will look like it did when the print was wet.

4. Why can’t I produce the same results each time?  What am I doing wrong?  Nothing.  That’s a quirk of toning.  If you have a batch of prints that need to look similar, try toning them all at the same time with the same solution.  Otherwise you run the risk of variations that you may or may not like.  If you’re still having issues, stick with the basic tea toner – it’s a little less fickle.

5. My print looks mottled – it didn’t tone evenly.  What’s going on?  If you’re leaving the print in the toner for a long period of time, make sure you place it face down.  Paper floats oddly, and you may end up with “dry” spots that don’t tone evenly.  If you’re toning face up, make sure you agitate the print constantly.

6. My print has a bright blue round spot on it!  Yup, the curse of the air bubble strikes again.  Make sure the print is lying face down – ease the print into the toner slowly and work all the air bubbles out past the far edge.  If you already have the blue spot on it, try a quick rinse, bleach bath, and return the print to the toner for a bit to remove the blue.

7. My shadows are blah.  What happened to my perfect exposure?  Your original shadows need to be a nice, deep, cobalt blue to tone dark.  If your shade of cyanotype isn’t dark enough, it’s not going to tone well.  Read this tutorial and do some experimenting with your paper and your developer first before you try toning again.

Cyanotype toning: the basics « MP Photography.