Thursday, February 18, 2010

Worlds Most Useless Machine Build - Part 5

Building My Own Version of "The World's Most Useless Machine"
Part 5 - SketchUp Model 

My First Video Blog

I think I need to be committed over this project because I know I have gone over the top now. I created a Google SketchUp model with animation to show how the machine will be built. Actually there was a good reason to make a 3D model and that was to help me figure out all the mechanical stuff. Working it all out in the virtual world is a whole bunch easier than making the actual real stuff. It's real easy to move or re-size a piece on the fly with SketchUp.

But just to prove just how far gone I am I created a couple of videos and uploaded them on YouTube. One is an animation of how the machine will work. And the second is my video blog on how I used SketchUp to help me design the machine.

Video Blog - How I used SketchUp to help me design this machine.







Let me know how the idea of a video blog works out.


Edwood

Friday, February 12, 2010

Worlds Most Useless Machine Build - Part 4

Building My Own Version of "The World's Most Useless Machine"

Design of the Wooden Box
Yay We're Talking Wood Again!

Since I am building the box from scratch I am free to design the dimensions as needed. The goal is to make it just the right size to fit the mechanism and in proportion. I choose to use 1/4" x 3 1/2" Red Oak stock to build the box with. Probably the best joinery technique for such thin stock is finger or box joints. Thinking it would be fast and easy to make a box joint jig for my table saw to cut out the parts. The ShopSmith show this week just happened to feature just such a jig. Well I made one up but it turns out you really need a special flat grounded box cutting blade to make nice tight joints. I don't happen to have one and at the price they are selling them for buying one is not on my short list.

But I do own a fabulous Incra Jig for my router table can can very easily make box joints. Again however you do need exact diameter straight bits to cut the proper joints and as luck had it my good 5/16" bit was a tad too big. My first test joint ended up fitting too loose. I did find an old 1/4" shaft bit from an economy set that was just a tad undersized. Because of the micro adjustments of the Incra Jig you can compensate for the slight under-size and this time my test joint came out really nice.

So I am confident I will be able to make some really nice finger joints for my box with my Incra Jig. It will be easy to cut some slots in the sides for the top and bottom on my table saw.

Now I just need to figure out what size the box needs to be...

Wednesday, February 10, 2010

Worlds Most Useless Machine Build - Part 3

Building My Own Version of "The World's Most Useless Machine"
Part 3 - Obsessed Much? 
 
Louise has been pointing out to me that I have been totally obsessed with this project. I admit it I am! But on the plus side I am having a ton of fun designing it and have been learning new tools (electronic types) and refreshing my skills. It's been a very long time since I just played with electronics rather than working in the field for a living. I have forgotten how much fun it is to design circuits which is why I went to school after all.

So one item on my design list I can cross off is how servo motors work. I was rather surprised how little is written about how they really work on the web. Lots about mounting tips and what controllers to use but very little about the guts of the motors. I was curious so I kept digging and found a few pretty good sites:

***** NERD ALERT ***** 

 Read the following section only if you are a nerd like myself LOL


The second site gave me a big clue about how torque was generated in a hobby servo motor and why one direction will have more than the other director. This is important because on the Useless Machine one direction will be moving the control arm up to turn off the power switch and needs more torque. Basically the position of a hobby servo motor depends on the length of a pulse between ~1ms to 2ms is. A pulse of ~1.5ms will put the servo position in the middle of it's range. The range is typically 180 degrees of movement. The direction the servo moves with the long 2ms pulses is the direction to chose to the switch.

***** END NERD ALERT *****


So now with a better understanding of how hobby servo motors work I can go about designing my control circuit.

World's Most Useless Machine Build - Part 2

Building My Own Version of "The World's Most Useless Machine"  
Part 2 - The Plan

After seeing SaskView's video I saw a link back to his complete build instructions on the Instructables   Web site where he posted a great set off build instructions. I spent a lot of time reading the instructions and all the great comments. I took a look at all the variations people built and the troubles they had with the electronics. I even posted a few helping tips for some of the electronic questions. I noticed that most people where having so much trouble with the electronics they got around it altogether by just modifying the servo motor and using simple switches bypassing the electronic timer circuits. Well that is a simple solution to a complex problem for sure!. But since I really wanted to apply my electronics skill I went against my general principle of "keep it simple stupid!" and I will be controlling the motor with electronics. In fact I am going to expand the circuit by adding a second timer circuit to give the machine a slight delay before the motor starts. After looking at the the posted example videos I felt it might need a tad delay for effect.

So here is my design check list:

1.  Figure out how hobby servo motors work and how to control them.
2. Design a control circuit that uses a dual 556 timer with one side for the delay and the other side for the motor.
3. Design a nice box to house the machine.
4. Design the mounting for the motor, circuits, battery etc.
5. Design the arm that lifts the lid and turns off the toggle switch.

Seems simple!

Worlds Most Useless Machine Build - Part 1

 Building My Own Version of "The World's Most Useless Machine"
Part 1 - Introduction

I have been looking for a good project where I could combine my two major skills; woodworking and electronics. When I saw the YouTube video - The Most Useless Machine Ever! last December I cracked up laughing! And I knew I found the perfect project where I could apply my increasing skills in wood crafting with my already professional electronic skills to make a item that is just plain fun. I will posting my progress of the design and final results. I am planning on making copies for sale on my ETSY store!

Anyway take a look for yourself if you haven't already seen the video, its been a viral hit on YouTube