Sunday, August 19, 2012

Canon MP700 Copier Printer Fax Scanner Tear-down

Some time back I wrote about the Canon MP700 that my neighbor had given me, and my attempts to get it running.  It WOULD have made a really nice printer, but Canon's apparent policy these days is "you must take the device to a certified service center".  I guess they weren't getting enough of some sort of kickback, or too many botched DIY repair guys like me calling them for help.  In any event, I wasn't putting any more money into it after sinking $53 into a new set of ink cartridges.  (which I still have,  opened and installed but never printed from, obviously, if anyone would like to help me not eat the full cost of them - I could ship them sealed in baggies).  So, I decided to tear it down and scrap every last good part I could from it.  In the process, I scored some really nice parts and made some cool finds.  I also learned a bit about how to build cable restraints into a device and how to daisy chain smaller ground plates throughout a system so that everything, no matter how remotely tucked away, has easy access to ground.

MP700 with scanner and upper paper handler removed

My favorite find was all the stepper motors.  So far I pulled three disk style motors out and there is one large cylinder motor which is the print carriage motivator.  There's also a smaller paper handler motor yet to be pulled.  I like stepper motors due to their potential for enabling automation in small projects - something I love to ponder but haven't had the time or resources to pursue.  Now I have at least some resources!

Naughty motor on the Prt Scr button launched
a hundred Save Screen Shot applets in Linux Mint.
I plopped on the Esc key to clear them.  Took about 10 min.

Perhaps the most interesting find was an actual TUBE on the analog circuit for the phone cable pass-thru.  A tube of all things, tiny as it is.  I thought that was pretty neat.  I tried to get a picture of it but it was just to small for my cell phone to see.  It was clear, shaped like a short Christmas tree light and had two unconnected anodes inside.

One obvious bit of goodness was all the momentary contact switches provided by the control board - around 40.  These are the same kinds used in your computer mouse.  So, not only do I have a good stock of them to work into my own projects, if my favorite mouse wears out, I have a chance of being able to restore it to good working order on my own, or I might even build my own mouse or controller.

The most numerous find was all the screws.  Machine screws, screws with lock washers, and ubiquitous self-tapping screws.  I good heap of them.  My wife said, "I'm sorry, I just don't get excited about the screws."   I just left that one alone.

Results from an afternoon spent un-screwing around.

A cool item was the flat bed scanner imaging bar.  It both emits and detects light.  At first I thought it might be cool to turn it into a hand held task light, but I might see if I can turn it into a motion activated area light for under the counter.  That would be pretty neat, I think.

Last but not least, I also harvested a number of nylon or plastic gears, rollers springs and shafts.  All good parts for building things.  My goal at some point is to build my own 3D printer using many of these parts.  I have just about enough just from this tear down, and I have another HP Ink Jet printer and a very old flat-bead scanner to tear down yet.

There's something therapeutic about tearing apart a device one screw at a time. I learned some things, had an actual excuse to listen to my 80's Pandora station somewhere besides work, and just enjoyed unwrapping the present my friend gave me one piece at a time!

Friday, July 6, 2012

Weekend Project: PVC Blow Gun

I'm a firm believer that in order to teach respect, the danger of a lack of a respect must be well understood.  In polite society, crassness is the least of the problems that flow from a lack of respect for one another.  With kids, respect is paramount to their well-being, both at home in a peaceful relationship with family members, and outside the home when dealing with other kids and adults.  Respectful children are almost universally recognized and praised as worthy companions.  We would all do well to be respectful to the people around us, and of the things around us... especially the dangerous things.

Dangerous things come in all forms.  Potential kinetic energy is all around us.  A rock perched on a deck railing has the potential energy of its mass and the height at which it is perched.  As a rock falls at 9.72 m/s squared, it gains momentum and speed.  When the rock comes to a stop, its kinetic energy is transferred into whatever it lands on, whether it's a siblings head or a toy car or just the good ol' earth.  Damage will be done in some form.  A failure to respect this fact will result in injury.

Putting kinetic energy to practical use is one of man's crowning achievements in the engineering arts.  The humble blow gun is a fantastic opportunity to look into such variables as mass, air pressure, drag, mass and velocity. To make a blow gun, you're only going to need a few thing easily had at Lowe's or any other reputable hard ware store.  I made ours from 3/4 inch pipe adapters (for the mouth piece) and ordinary 1/2 inch PVC schedule 40 pipe.  I used standard two-part epoxy to weld the pieces together to ensure a good seal that would hold however much pressure we could blow through it.  We used 30" pipe sections and made four blow guns so everyone can have fun.  Maybe we'll decorate and personalize them later.

1.  Use a disposable surface to mix your epoxy, such as a cardboard box.  This stuff is pretty much permanent and you don't want to apply any of it to yourself or your fellow humans, so beware.  Also, the fumes are icky.
Here we made a good puddle, mixed for 2 minutes, and then dipped the end of our pipe in it and
swirled it to coat thoroughly.  Twist together to coat the adapter and then press firmly for 30 seconds to set up.
Once assembly is complete, the mouth piece I chose needed a little finish work for comfortable use owing to a lip in the plastic casting.

2. File or sand down lip, if any, for comfort
When blowing through the gun, the pressure tends to move your lips out a bit which can become uncomfortable after a few shots.  I used 200 grit sand paper to smooth the inner surface down and all was well.

For our projectiles, we experimented with a few things.  I first bought a bag of 3" wooden golf tees.  As we found, they lacked sufficient mass to penetrate our test target, a cardboard box.  Next I tried sling-shot marbles with some cloth wadding in front of it to keep it from falling out the other end of the pipe.  The marbles did pretty good damage owing to their mass.  The weight of the shot and it's near perfect fit in the pipe allowed most of the force of air being blown through the pipe to go into accelerating the shot.  The end result was some pretty grievous dents in the box, but no penetration.  For the purposes of our experiments, we're equating penetration of a layer of card board with "kills a rabbit" though I doubt we'd be able to achieve that in real life.  We're just killing imaginary cardboard rabbits.

With our 30" gun, the range is pretty limited with most projectiles we came up with.  The best was a 16 penny nail pushed through an inch square of cloth.

3.  Cut a 1 inch square of scrap cloth and press a 16 penny nail through the center.
The nail has sufficient mass to carry through and penetrate target (hence "kills a rabbit").  The cloth provided two functions.  One, as shown below, it provided wadding to accept the air we were blowing down the pipe.  Without it, one's breath would simply pass around the nail and it would only slide out of the pipe rather than fly from the gun.

4.  Wrap wadding around nail head to form a plug.
Carefully inserting it into the back of the pipe keeps the nail from pulling the wadding all the way down the pipe.

5.  Our "dart" is loaded into the "breech" of our "gun".  
Rabbits everywhere tremble in fear and run away to hide in their holes.
Then, just aim and BLOW!!!

6.  Keeeled a rabbit!
The gun lacks any useful accuracy, but is NONE-THE-LESS dangerous.  A 16 penny nail flying through the air for 15 feet with enough kinetic energy to poke through a single sheet of cardboard will MOST DEFINITELY BLIND someone so unfortunate as to be in the way.  This makes this a very dangerous toy and ADULT supervision should be observed at all times.

Other than that, have fun cramming stuff into the back of the pipe and seeing how far a good hard blow will send it.  It took me about 25 shots with various projectiles to grow tired of it.  Good clean and dangerous fun.  Perfect for a father on any given weekend.

Taking it further

A longer bore would give more time on acceleration before the wadding cleared the end of the pipe and your blow was no longer providing thrust. Maybe 2 meters of pipe would be better?  This would improve the accuracy, and lethality of the gun.  One could also epoxy a small brad to the end of the pipe as a front sight so that more practiced aim could be taken over time.

As for the darts, I'm sure a hat pin and cotton ball would be a better choice.  The hat pin has less mass than the nail, but greater mass relative to the size of the impact area which contributes to the resultant penetration on target.  With our nail, the surface area to mass ratio is sufficient for the nail to carry through.  With the marble, the surface area was much higher relative to the mass, so all we got were some gnarly dents.

You can probably do better than an unmarked cardboard box as your target.  My eldest minion made some nice circles with a pen, but my vintage vision couldn't see them clearly at firing range!

Thursday, May 17, 2012

Tearing it Down

I've mentioned in the past my habit of collecting useful bits of hardware and sorting them so I have what I need later.  Sometimes you have to dig for useful bits, or rather, you should.  In my case, I had some old kid hauling equipment in bad shape from years of garage storage and reuse as play items.  Sitting there, dirty, housing mice and spiders, a car seat and a stroller went under the knife tonight. And the tin snips, and the cordless screw driver, wrench, and a hand small log cum impromptu mallet.

As a result of an evening of gleeful destructive disassembly, I have added approximately 20 screws of various sizes, several different gauge and size springs, lots of webbing and buckles, some wheels destined for a garden cart, and some bolts.  Left over is everything too big and too specialized to be reusable for much else but target practice.  But, not wanting odd bits of indeterminately sourced plastic all over my back woods, they will bet drawn and quartered as soon as I can find a sawsall on the cheap someplace.

Tearing down hardware is but one mode of thought though when it comes to useful destruction.  This past winter I also tore the trim off of three windows, milled and installed new trim after filling cracks and gaps in the insulation around our replacement windows.  My dad was a bit shocked to see I had torn them down to the casements and crusty drywall edges, but it was the only way the job could be done correctly.  Sometimes you have to do that.

My neighbor, Lance, gets this.  He was retained as a body man to fix a spot of rust on my car.  Lance is a Mormon.  If you know anything about Mormons, you should know that they know how to prepare for the apocalypse.  That's why it was no surprised to me that Lance hunted every trace of rust in the rocker and quarter panel, forcibly extracted it with a saw, rebuilt from stock galvanized sheet metal and welded into place a complex set of replacement parts, filled and ground the welds and repainted half the side of the van to an exact match in color.

If you're going to fix something, it's worth doing it right the first time, being thoroughly destructive of the malignant portions as much as possible.  Leaving behind any scrap of the old, defective and sometimes hazardous bits is only inviting it's return later.  Some people understand this principle, and some people are unfortunately oblivious to the reason and need for it.

So, I hope you'll take this cheery bit of advise from a plugger...  when you run up against something that is just sick with defect and you can do something about it, be thorough in your work, even if a bit more destruction than you anticipated is needed to excise all the badness.  Then, start with good materials and a raw determination to finish the project.  Otherwise, your windows will end up like mine - trimmed but not yet stained! (oops!!)

Tuesday, February 28, 2012

Design, Analyze and Test Circuits Online!

I have been thinking of something like this for years, but the goodly geeks at MIT Nerd Kits have created it - and let's face it, they have the skills I lack in the area of electrical engineering.  Circuit Lab is a virtual schematic designer and tester with many great tools.  Funnily enough, the day my DSONano oscilloscope arrived via FedEx, I find out about Circuit Lab from Nerd Kits.  Now you can see what putting 100v into a 555 chip does without blowing it to smithereens!

Check them both out if you want to learn how to make tiny circuit bits do their thing in useful ways.


Circuit Lab

I'm already in love with the DSONano just because it looks like a cool bit of Star Trek kit right in your hands.  It is packed with functions and I can't wait to actually be able to put it to practical use!