Intro to Making Puppets workshop on Saturday, December 7, 2013

I’m running another puppet workshop at VHS

Intro to Making Puppets workshop on Saturday, December 7, 2013

VHS is running another Intro to Making Puppets workshop on Saturday, December 7, 2013!

Bring your imaginations, concept art and materials!

All puppet styles are welcome, from finger puppets to sock puppets to “muppet-style” puppets (whew, trademark lawsuit averted!). Even sock-monkeys are welcome at this artificial creature creation party.

VHS will try to have some supplies available, including enough polyfoam for the first 10 muppet-style puppets or so. But if you have your heart set on making something specific, we recommend bringing your own supplies.

In all cases, scissors, needles, and thread are a good idea.

For a finger puppet, we recommend felt in the colours you prefer, and embroidery floss of matching (or interestingly contrasting) colour.

For a “muppet-style” puppet, foam, and a skin material of either synthetic fur or fleece in the colour of your choice.

For a classic sock puppet, fur, fabric or fleece in the colour or style you prefer. A sock would also work.

For a sock monkey, you will need a pair of socks, in a pattern and texture that you believe would make an attractive (or appropriately hideous!) monkey. And poly-fill stuffing.

If you’d like to get prepared early, we will be posting some handy links leading up to the event:

Finger Puppets!

Sock Monkeys!

Dressew is a good place to get almost everything you will need, with a variety of affordable fur and fabric ends available at reasonable prices in their scrap bin. 337 West Hastings Street Vancouver, (604) 682-6196

If you plan on bringing your own foam, we recommend Discount Foam , at 6035 Fraser St., (604) 324-2927. The best foam for puppets is reticulated polyfoam in sheets of 1/2″ thick, and 2′ x 2′ would be enough to build one one standard-sized puppet.

1 pm, Saturday 7th of December, 2013

VHS (270 1st Ave E, Vancouver)

Bottom liner: 
Steven Smethurst 

A response to Life tracking and Quantified Self movement.

A few days ago someone was asking about live tracking and productivity hacks this is my response to them.

I use timers on my phone, Google calendar, and a spread sheet. All portable tools that have there versions on just about every platform/system. (IOS, Outlook, etc)

First, everything goes in to my Google calendar, every appointment, every meet up, every time I go to VHS, every time I meet someone up for dinner, everything. I don’t trust my own ability to remember anything so I use Google calendar to help me remember. Google calendar also has the ability to add email/pop-up reminders, you can get an email a week out from the event or a popup on all your devices 1hr before. I believe the default is a pop up 10 mins before. This has been tremendously useful for far out deadlines, that are 6 months to a year out as I can email reminders every other month. With Google calendar you can also add in the location of events and my phone will auto map to these places and tell me when I need to leave to arrive on time.

At the end of the day or week I also back update my calendar with anything I randomly did that is not in my calendar. For example if I randomly met up with a friend on the street and went for dinner, I will update my calendar for this past events.

I been doing this for ~4 years now and because of it I rarely miss appointments with people and I have this beautiful log of everything I have been doing. I can tell you with a reasonable certainty where I was a year ago.(Dinner with my Sisters, where we talked about xmas gifts for my parents) or two years ago (Trip to Seattle for work) or three years ago (Dinner at Joeys Stake house, followed by a movie at Scotia Bank theater, then drinks afterwards). This is a beautiful data set of my life, and also a good alibi if I ever need one ;)

Next. I have two repeating alarms on my phone. Bed time 10pm Monday-Thursday and wake up time 8:30am Tuesday-Friday. (I don’t work Mondays) The 10pm bed time is just a reminder that I should be cleaning up and getting ready for bed, I rarely go to bed at 10pm but it helps me get started to thinking about it. You could do the same thing for dinner or lunch to make sure that you eat a regular intervals. (super important)

Last, The feed back loop, and self improvement. I use a spreadsheet to count points for doing good things. Along the top are columns for the date, and along the side rows are categories and things I want to track. When I brush my teeth AND FLOSS more then once a day I get a check mark in a column for that date. When I eat a vegetable, or go for a run or walk, or zero my inbox, or say something nice to my significant other, or read of an hour, cook something that is not box food, Filling out the self improvement chart, etc… I put add a check next to the date. I also put checks next to negative things, such as playing video games, watching TV/Netflix, or eating candy, etc… Each item is worth a different amount of points. The amount can be negative for bad things, negative for missing (like brushing teeth) or positive for good things. The amount can change per week as well as thing become more or less important in my life. At the bottom of the sheet there is a score for the day (total of all the points). With this score I can chart myself for each week or month so see if I am in a upwards trend or if I am in trouble. I did this for a year and my results where mixed. It was too much effort to fill in the spread sheet every day.

I tried to automate it but creating a jabber chat client that would ask me questions about my day near the end of the day (did you eat a vegetable today?) and recorded the answers in to a database for me but I also found that annoying (fuck you, your not ma Mom!). I gave up on my spread sheet after i built the app and when the app got annoying i never went back to the spread sheet. Regret

Anyways, I highly suggest that you NOT build a new system for this on the raspberry pi. Use existing tools that can be moved from one system to another. Don’t focus on the technology, focus on the results. Start by using the tools that are available right now and use it for a few months, after 3 months, reduce an refine the process and maybe automate some of it.

Also look in to the “Quantified self movement” where you will find a huge amount of research on this topic and tones of tools that other people are using.

Good luck.

How a Greyhound employee stole alcohol from my checked luggage.

See below the letter I sent to Greyhound. I will update this post if/when I get a response from Greyhound


Conformation number: #18325413
Seattle to Vancouver, BC 04:05PM Nov 11th 213

I arrived at the Seattle Grayhound station and checked in. My carry on and checked baggage was searched as was everyone else on the bus. They found 2x 12 year old bottles of scotch in my CHECKED baggage (costing a total of $120, Yes I have the recite) The baggage checker (Security?) told me that alcohol was not allowed on any Grayhound bus. I told him that this was my “check baggage” that was going UNDER the bus. He said that it didn’t matter, no alcohol on the bus. I told him that did not make any sense and he responded with “That’s our policy, you can have the alcohol or your bus ticket” I didn’t have any other choice and I left the alcohol with him before boarding the bus.

Once home I checked your website for the policy while writing a complaint.

And found that you DO accept alcohol in CHECKED luggage.
Your employee stole 2x bottles of 12 year old scotch from me by claiming it was against your policy to have liquor in your checked luggage.

It looks like I am not the only customer that this employee has taken liquor from. She was on the same bus as me.

You have two days (Thursday 14th, Nov, 2013) to respond before I report this to the local Seattle police department, Seattle and Vancouver local news papers, etc..


Introduction to Home automation with the Raspberry Pi – Sunday November 24th 2013

VHS members only, become a member and join us!

Bottomed lined: Steven Smethurst

RVSP on Google+, Facebook

Free for VHS members

VHS 270 East 1st (The Bunker)

Sunday November 24th 2013 1 pm till 5pm or when ever we are done.

In this workshop we will be using a Raspberry PI to read sensors (inputs), store their vales in a database for historical trending and turn relays (outputs) on and off when a sensor value goes outside of a certain range. There will be a small amount of very basic python programming in this workshop. Example code will be provided and even if you have never programmed before you should be able to get the basic example running.

In this workshop you will be building a system that will turn on a light if the door is open or motion is detected in an area. We will be recording the current temperature to a database and if the temperature goes outside of a range a fan will be turned on to reduce the temperature.

Before this workshop you should have your Raspberry PI loaded with an OS and have the latest version of Adafruite WebIDE running. It will also help considerably if you record your Raspberry PI MAC address and HostName on a scrap of paper before the workshop.

Hardware is NOT provided by VHS!!!
All the hardware can be purchased locally at Lee’s Electronics  (4522 Main Street). Tell them your a VHS member to receive a small discount. Or you can order all the hardware from they also have many other interesting components. Note there are Raspberry PIs available in the VHS vending machine at the space. If you buy your components from DealExtream expect them to take 6 weeks to be delivered. If you are unable to source all the components join us anyways VHS can lend you some parts for the workshop.

Parts list

If you would like to get started early we will be following these tutorials provided by Adafruit in this workshop

BEWARE! ShareMouse, MaxiVista, Bartels Media == Crapwear

ShareMouseOne of the many things that I can’t stand about software is crap where. Crap wear lets you install it on your system saying its “100% free”. When you get it configured and use it to the features it disables its self and gives you a pay wall. I have no problem with paying for software but when the developers out right lie to you I get pissed off.

ShareMouse (no link love for you) and Bartels Media produce crapwear. Beware of them, they make the world a worse place. They are BAD PEOPLE.

I found this software on Now to spend the next few hours writing horrible reviews about this crap software on as many websites as I can find. Maybe I can outsource this task with virtual employee.


Getting started with your Raspberry PI

The Raspberry Pi is a credit-card-sized single-board computer developed in the UK by the Raspberry Pi Foundation with the intention of promoting the teaching of basic computer science in schools

A good place to start is the Raspberry PI quick start guide This will describe the different components on the board and what they can be used for.

Downloading, installing and perparing the Raspberry PI OS

The Raspberry PI will run several different specialty prepared versions of Linux that have been compiled specifically for the Raspberry PI. The Raspberry PI team have created a image of several different compatible Raspberry PI Operating systems that can fit on a 4gb SD card. They called this image New Out of Box Software (NOOBS) and it can be downloaded from the Raspberry PI main site. The NOOBS Image makes this whole process a lot easier.

  1. Format your SD card using the SD Card Association’s formatting tool. 
  2. Download the NOOBS image file
  3. Unpack the NOOBS zip file onto the SD card (in to the root not a sub directory)
  4. Insert the SD card in to the Raspberry PI, Connect the monitor, keyboard and power.

For this tutorial we will be using the Raspbian OS. Raspbian is an unofficial port of Debian Wheezy and has been specifically modified to work with the Raspberry PI. Its also part of the NOOBS image provided by the Raspberry PI team.

  1. On start up you will be asked what OS you want to boot to, Select the Raspbian OS
  2. After the Raspbian has been installed, Your Raspberry PI should restart and display the Rasppi-Configuration screen. Select “advanced options” from the menu and change the Host name to something unique. The new hostname will not come in to effect until you restart your device.
  3. Before restarting your Raspberry PI, write down its MAC address (HWaddr) and IP address (inet addr)
    1. From the terminal window type


  4. Restart your Raspberry PI

Connecting to your Raspberry PI with SSH (running headless) 

By default the Raspbian OS comes with SSH enabled. This allows us to run the Raspberry PI without a monitor or keyboard (headless) and connect to it from another computer (our laptops) remotely.

If you are on windows you can use Putty ( ) as your SSH client. MAC and Linux both have built in SSH clients.

The default username is pi and the password is raspberry

Installing the AdaFruit WebIDE

The instructions on AdaFruit’s website are straight forward with plenty of pictures.

Raspberry PI and the GPIO pins

More details:


Home made Raspberry PI GPIO ribbon cableThe Raspberry PI has a 26pin mail connector that connects to its GPIO pins. These ribbon cables and breakout boards can be found on ($2.95) and Sparkfun ($2.95)

You can also make your own. Hardware lesson with Gert: make your own ribbon cable connector.

Source code 

Since I am using bitbucket all my source code is public. I created a few learning scripts to understand how the GPIO pins work on the Raspberry PI. The first script I made was a simple blinking LED, just like the arduino blinking LED script. Next was to read the current state of a switch and print the results to the screen.

This image was tremendously helpful in figuring out what pins go whereRaspberry-Pi-GPIO-Layout-Revision-1-e1347664808358

# Blinkly Script
# This script will blink a LED ON and OFF again.
# Created on Feb 2, 2013 by Steven Smethurst
# Version: 1.00
# Directions
# Connect a LED between Pin 6 ( Ground) and pin 12 (GPIO18)
from time import sleep
import RPi.GPIO as GPIO
# print about info
print "Blinky script, v1.0"
GPIO.setup(12, GPIO.OUT )
while 1:
GPIO.output(12, GPIO.HIGH )
GPIO.output(12, GPIO.LOW )

Quick and easy word clock with a spare monitor and JavaScript

2013-09-04 22.36.28We where talking about Dougs Word Clock design at VHS this week trying to figure out the cheapest and lowest labor way of designing the clock. LED strips or shift registers, how about a relay board and an Arduino. After much discussion we came up with the idea of using a laser cut a sheet of wood that has all the different words cut out as a mask for a monitor. We placed the sheet of wood in front of the monitor and use JavaScript to illuminate certain parts of the screen to highlight words.

This hack took about two hours to complete as none of us knew JavaScript, and turned out pretty well.

Demo of the javascript application
Source code can be found on github javascript word clock



Getting started with Raspberry PI – Wednesday Sep 11th, 2013 @VHS

I am running another intro to Raspberry PI night at VHS this week.
Join us

The Blink sketch is the most basic sketch for most micro processors (Arduino, Launchpad, etc..).  Its a very simple sketch that just turns on and off an LED. You can do the same thing on the Raspberry Pi with the GPIO pins. Its a good start up tutorial for getting you started with your Raspberry PI, Adafruit WebIDE, and Python

What we will be doing

  1. Installing and Updating the OS working on your RPi
  2. Connecting and using SSH on your Raspberry PI
  3. Installing the WebIDE,
  4. Using Python and the GPIO pins to get an LED to blink.

Things you will need

  • A Raspberry PI
  • A power supply (>= 750 mA) and Mico USB cable for your Raspberry PI (Note: Power supplies are available in the vending machine)
  • A keyboard and mouse, (VHS has a very limited amount of spare keyboards)
  • A laptop (VHS has spare laptops)

VHS (270 East 1st, Vancouver, BC, Canada)

7:30 pm Wednesday Sep 11th, 2013

Anyone that is interested in the Raspberry PI no matter what your skill level.
Steven Smethurst (funvill) will be running the night.

Because the Raspberry PI are awesome and this will be a good prep night for another upcoming raspberry PI night on Sunday
Sunday September 15th, 13:00-19:00: C/C++ on Raspberry PI @VHS


GeoGramOne – GPS tracker to Google maps

GeogramOneTop2A few weeks ago I ordered a GeoGramOne board from DSScircuits. Its a Open source GPS tracker that was succefuly funded on Kickstarter. The board combines a GPS, GSM Modem (cellphone), Arduino (Atmega328p),  lipo fuel gauge, and 6 axis digital accelerometer.

With the default firmware you could send a SMS message to the device and it would reply with a SMS with its current location. It had a few other interesting features that used SMS as the transport layer for the GPS coordinates.

The board design and the firmware are all open source. This means that I can edit the firmware to do what I want it to do. Getting the GPS coordinates via SMS is great when you want to actively know where the GPS is at that exact moment. But I wanted to use this board to actively track and records the location of the GPS as it travels around. Preferably I wanted it to ping my web server with a HTTP Post every 30 secs or so.

I found the the DSSCircuits forum that some people have edited the firmware to send UDP packets to a server to get real time updates of the GSP’s location using a website called GPS-Trace Orange.

UDP is much smaller of a payload then the HTTP POST message that I want to use, but I can’t set up a UDP server on a cheap web host. It also makes it harder for other people to use the code that I make.

I made a bunch of posts on DSSCircuits and and was able to update the code to send HTTP post messages to my web server and automatically generate a Google map of the path of the GPS over time.

The updated version of my source code can be found in my github account. If you run the code as is from my github your GPS will send its coordinates to my web server and your device will show up on this map.



The Giant Claw Game! – Post Mortem

Things didn’t go as planed, the claw broke with the very first kid. I added min and max limit switch to the claw to tell when the claw was fully open or fully closed. The problem is that the claw does not know it has picked up a toy or not. So the first kid picked up 5 toys at once and started closing on the toys and squeezed and squeezed trying to hit its min limit switch and rip it self apart.

I quickly changed the claw to a magnet on the end of a string and added metal things to all the toys in the ball pit. Instead of a claw, they picked up the toys by connecting the magnet to a bit of metal on the toy and winding it in. Defiantly not what I planed but it actually worked better then the claw ever did.

The next problem was the little battery that I brought ran out juice faster then I could recharge it. I had to borrow a car battery from a friend and exchange it for the smaller battery that I had. The bigger battery with the charger lasted the entire weekend.

Next problem was I had a really hard time saying no to kids that wanted to play more then once. I didn’t have enough toys for everyone so if I let a kid play more then once that would mean another kid couldn’t play.

People would not accept that I was giving toys away for free. People would ask how much it costs and when I told them it was free they would give me a puzzled look. Some people just left money on the table. Over the weekend I collected $25 from people that refused to accept that it was free. I donated this money to VHS.

Kids that didn’t want the toy that they got could exchange it for candy (sugar free, no nuts, etc..) Most of the time the kids would want the toy but the parents would rather them have the candy. Less things to clutter up their house, I guess. Some kids got so upset that they didn’t get the toy that they wanted that they would scream at me, call me names and throw things at me… I didn’t have too much trouble sending these kids packing without a prize.

Over all I had a really good time, I don’t think I would ever do it again. It was a stressful, expensive, exercise that took its toll on me. Next year I plan to do something simple that does not require my full attention.

The Giant Claw Game! – Pictures

The Cart

The cart will be used to move the claw around the XY table. The cart will also have a spindle on it to raise and lower the claw. The spindle is powered by a drill motor. I still have to figure out a way to run the power and data wires to the cart without the wires getting tangled up, while the cart is in motion.

Originality the cart was attached to the cables with springs. The idea was that the springs would add tension to the cables making it easier for the motor pulleys to grip the cables. What actually happened was the springs buffered the movement of the cables and the cart moved in jerks. I replaced the cable with a tensioning hook (I am not sure what they are actually called) and it became smoother and more responsive.

2013-05-22 21.31.56 2013-05-23 08.46.48 2013-05-20 16.26.54 2013-05-20 16.26.49 2013-05-20 16.26.58 2013-05-22 18.39.35


I cheap out on the pulleys at the start. I bought cheap home-depo ones that where basically a round cylinder with a pin thou the center. They worked but added lots of friction to the claw, making it harder for the drill motors to move the cart around. After struggling with these pulleys for a few days, I decided to use ball bearings and washers instead. The ball bearings cost a lot more but they worked great and dramatically reduced the amount of friction in the system.

2013-05-22 18.39.48    2013-05-22 18.39.32 2013-05-22 18.39.35 2013-05-22 18.39.40

Drill Motors/Motor Pulleys

The motor pulleys came from the junk yard and have several different levels that effect the speed and grip of the cables. I selected the largest diameter level as it would have the most surface area to pull the cables around, but it also has the side effect of moving the cables at a much faster rate then I would have liked.

I am planning on experimenting with the different pulley levels to see if I can reduce the speed while keeping the cable from slipping.

The drill motors are also really hard to mount without their plastic cases. I attempted to strap the motors in with wire straps but they keep coming lose under strain. I need to find a better way of mounting them.

2013-05-22 18.39.43 2013-05-20 18.36.52 2013-05-20 18.36.47 2013-05-20 18.36.45 2013-05-05 15.13.00


The Giant Claw Game! – Problems

The Giant claw game can be broken down in to a few parts. The Claw, The Joystick, The Gantry/Cube, The XY table, The Cart, Control system

The Claw 

2013-05-18 15.06.03The claw is working and it is in pretty good shape. The claw can open and closes and pick up toys. It uses a small gear motor attached to the top. The gear motor is kind of slow and takes about 20+ seconds to fully close. I am thinking about replacing this motor with one of the drills to speed it up.

I have attached limit switches to the claw so I can tell when it is fully opened and closed. This prevents the claw from crushing the stuff animals.

Bill of materials

  • 2 Cherry limit switches,
  • Terminal strip
  • Small geared motor
  • Motor shaft coupler
  • Wood

Claw limit switches  2013-05-18 15.05.50 2013-05-18 15.05.57

The Joystick 

2013-05-18 15.15.19The joystick is the simplest part of this system. It has 4 limit switches and a off the shelf  joystick that I picked up from John Jukes. All the wires lead back to a RS45 connector to make setup easier. I wanted to make this part strong in case the kids drop it and kick it around. The only thing left to do here is glue the box together.

Bill of materials

  • Wood
  • Arcade button
  • 5 Cherry limit switches,
  • 1 RS45 connector

Joy stick Joy stick wiring

The Gantry/Cube

The cube is pretty much a large wooden box made out of 2x3x8. I added trusses to the corners to make it more stable. I added the shelf to the top of the cube to allow the gantry system to ride on top of.

marqueeI would like to add a marquee banner to the top of the cube to make it look better. I am also planning on adding some fabric to the bottom so all the toys will gather in the center, making it easier for the kids to pick up a prize.

There is a lot I could do her to make it look better but I am running out of time and I may not get a chance before Breaker/Maker Faire.

Bill of materials

  • 16 2x3x8 wood beams.
  • 50+ 3″ screws
  • 4 appliance moving wheels
  • 12 pulleys
  • 45 feet of rope.

2013-05-05 20.19.25 2013-05-04 11.55.31 2013-05-12 18.46.37

The XY table

CoreXYThe XY table moves the claw around the cube. I decided to use the CoreXY (Cartesian Motion Platform) to do the actual movement. It works but there are many problems with it that I have not resolved yet.

2013-05-19 19.56.56The biggest problems I am currently having is that the cables that I am using are slipping in the motor’s pulleys. I tried using some sandpaper to rough up the pulleys to add more grip but they keep slipping.

2013-05-19 20.06.54

I thought about adding a idler pulley but I wanted to keep everything as simple as possible and I decided to add expansion springs to the cables to keep the tension on the motor pulleys. Its still slipping.

The problem also could be with the cables I am using. If the cables are too slick they will slide around in the pulleys, if the cable has too much give they will stretch under constant use. I had some parachute cord (paracord) around my house and decided to use it and this might be adding to my slipping.

Another idea is to wrap the cable around the pulley twice (540 degrees). This would ensure that there is tension on the pulley but the cable might get knotted up.

I have not resolved this problem yet and I am looking for a solution.

2013-05-19 19.57.03 2013-05-19 19.56.26 220px-Paracord-Commercial-Type-III-Coil

The Cart

I have not started this yet.

cartThe cart will ride along the center column being pulled across by the cables. The card will have its own pulley on it that will be used to raise and lower the claw. Here is a crude drawing of what I was thinking about doing.

There will be one large pulley that will rise and lower the main claw. this pulley will be at the bottom attached at the center to a dowel that is free rotating in the walls of the cart… kind of hard to explain.

Control system

I am using a relay H Bridge to control the motors. Each motor needs two relays and two pins on the Arduino. There are a total of 4 motors in this system (8 pins). One each for each of the axis X, Y, Z and one more to open and close the claw.

I also used a lot of limit switches to tell when the claw is in a certain state.

  • 4x for each axis on the gantry,
  • 4x for each directions in the joystick,
  • 1x for the fire button on the joystick,
  • 2x for the min and max of the claw’s teeth,
  • 1x for the pulley to know when the call is fully retracted in to the cart.

A total of 20 pins. An standard Arduino has 20 pins, just enough to control the claw. I am trying to make all the connections with RJ45 connectors for an easier set up.

The programming for the Ardunio is nice and easy and pretty much done already.

8 relays  cherry switch  2013-05-19 22.32.56


Still lots to do and not much time to do it.

Breaker Faire – May 25th 10am-5pm

Like to BREAK things? Visit the Vancouver Community Laboratory for your chance to smash a car! For just a few dollars, you can take part in a scrumptious pancake BREAK-fast, WRECK a car, have your mind BLOWN by local art / creations, and PLAY a giant claw game! Wreckage form the car will be used by local artists for materials, and all proceeds benefit the Vancouver Mini Maker Faire.

All ages. Entrance by donation.
Saturday, May 25, 10 am – 5 pm
1907 Triumph St.

Click here for information & updates via Facebook

More information at Vancouver Maker Faire

The Giant Claw Game! – Relay H-Bridge and Circuit Design

Over the week I worked on the Relay H Bridge,  software and circuit diagrams for this project. Only 1 more week till it needs to be done.

Relay H Bridge 

After finding out that my L298 H Bridge was not powerful enough to operate my gantry motors last week, I switched over to use a Relay H Bridge. The advantages of using a relay instead of the L298 is that the relay can take a lot more current but the switching frequency is much slower (~40 hz)

1 0 Forward
0 1 Reverse
1 1 Motor stop
0 0 Motor stop

Relay H Bridge

Image source:

Circuit Design

I don’t have much experience with circuit design but I think this makes sense. I built it with and online circuit designer.

 big-claw-game circuit


Arduino Software

The code for the Arduino is pretty strait forward. Move the claw around until the fire button is pressed, then drop the claw and pick up a toy and bring it back to the start location. The source code for the The Giant Claw Game can be found on my GitHub account.





The Giant Claw Game! – The Controls System

Only two weeks left to get the Claw up and running ready for Breaker Faire the Maker Faire fund raiser party. I am starting to get worried that I might not get it done in time.

I have been having lots of problems this week with getting the motors working with the gantry system.

  • The motors are from different vendors and move at different rates.
  • The motors draw too much current for the motor shield to handle.
  • The motors are hard to mount on the cube.
  • The pulley for motors slips and I am unable to get them to move the cables.

3 drill motorsThe motors come from old power drills that I picked up at a local flea market (Binners market). You can pick up some pretty amazing things at this market when you look hard enough. I purchased 5 battery powered drills for $5 each, 4 of them worked.  The picture shows three of the motors taken apart with the supply voltage taped to the motors. Drill are great for finding cheap motors with a gear box and a chuck. A retail motor with a gear box would probably cost me in the range of ~$30 each. The problem with getting second hand motors is that I couldn’t get all of the same type of motor. Luckily, of the four working drills two of them have relativity similar gear ratios and power requirements. Even still the minor differences between these two motors will probably cause me problems after a few hours. I think I can resolve the difference by providing different voltage to each of the motors, its not ideal but it should work.

l298I purchased two L298 Dual H-Bridge Motor Driver from They work great and are easy to interface with, but they have a 2 amp max current limit. After experimenting with the motors I have I found that they require 1.5 Amp to starting current and probably need around 6 Amps to move the gantry around properly. Way too much current for these motor shields.

Motor controller

After doing some more research and asking a few questions online I decided to build a relay version of a H Bridge instead. The advantage of using a relay is that it can take a lot more current +10 Amps but its switching frequency is much lower (~40 hz) and it costs quite a bit more ($5-10 per relay).

I designed this circuit in circuit lab (online social circuit building tool). I am planning on picking up the parts and building it tomorrow. Hopefully this will resolve the motor current problem I was having.

motor mount The next problem was how to mount the motors on to the cube. I wanted to use a hole saw and cut a circle in to a 2×4 and then attach the 2×4 to the cube. But I didn’t have a hole saw so I ended up using a jig saw and a drill. The results worked but didn’t look pretty. I might end up redoing this work if I can find a friend with a hole saw.

I also have to figure out a way of making pulleys for the motors that can pull the cabling and move the XY table. Normally I would have used a timing belt instead of cables. The rubber teeth inside the belt would have added the grip on the pulleys that I needed. But timing belts are really expensive. The two belts that I would have needed for this project would have easily cost me more then the entire project has so far. Still trying to figure this one out.

Still lots to do but things are coming along.

The Giant Claw Game! – The Gantry System

This week I have working on the gantry system. The gantry system is used to move the claw around inside the Cube.

Skycam I was originally planing on attaching the claw to 4 cables running to pulleys in each of the corners of the cube. The cables would be attached to four electric motors. Just like the sky cam that you can some time see at stadium.

2013-05-05 20.19.34I ended up not using the sky cam and going with a more traditional XY table. With a sky cam I would have had to have four matching electrical motors in each corner. To move the sky cam North/East/South/West you need to move all 4 motors in sequence making it more complex of a system.

CoreXYI decided to use the CoreXY system for the claw’s XY table. Its a brilliant simple system that uses cables with only two motors instead the normal 4 motors. The system does need 8 pulleys two work. Rotating both motors in the same direction results in horizontal motion. Rotating both motors in opposite directions results in vertical motion.

I added a shelf on the top north and south sides of the cube. The shelf will carry the X axis (blue)  up and down along the Y axis (red) giving the system its vertical motion. In the first picture you can see the wheels and the X axis bar.

Y axis  Top of the Cube Claw with a toy

I added the wheels to the X axis bar, installed the 8 pulleys and ran cabling thought the system. Using my fingers I pulled the cables back and forth to move the XY stage around. Everything worked!

Next I am going to add the motors to the gantry system and get everything moving around.

The Giant Claw Game! – The Claw, Prototype 3

I started working on the third version of the claw this week. In this version I have added a motor, extended the length of the prongs, and started on the electronics.

Direct drive with home made shaft coupler At first I tried using a direct drive electric motor that I found at VHS. I constructed my own shaft coupler out of sheet metal and hotglue. It worked but it had no guts. As soon as the smallest amount of force was applied to the claw it would stop moving.

Gear motorNext I upgraded to a small geared motor, 12v 36x gear, 100RPM motor.  This motor could easily crush a play pen ball in the claws. It had a ton of torque but it was slow. It took upwards of 30 secs or more to close the claw from its fully open state. I also found a local supplier of shaft couplers that made attaching the motor shaft to the screw much easier.

Claw's extended prongsI extended the length of the prongs to speed up the time it took to close the claw from an fully open state. I was able to reduce the time from 30 secs to around 22 secs. It took me many iterations to find the optional length for the base plates that I have. Still took long.

Limit switchesI changed focus and started working on the limit switches. These switches are used to tell when the claw is fully opened or fully closed. It took a while and a bunch of configurations before I found one that worked.  I added a terminal strip for cable management to try to keep things organized.

I also built the wooden frame “The cube”. I added trusses to the frame to reduce the wobble. Its a cube, not much to say about it.

The cube

I am planning on working on the XY table tomorrow. The XY table is used to move the claw around the cube in 2D space.