Repairing a Canon G11 Dial

March 10, 2013

I take most of the photos for my blog with a beat-up Canon PowerShot G11. It’s an older prosumer camera with a known hardware issue: the control dial for the manual settings will gradually fail, and setting exposure, shutter speed, and manual focus becomes progressively more difficult and eventually impossible.

The fix is pretty simple if you’ve got a small Phillips screwdriver, an electronics cleaning solvent, and some patience. I followed the steps on this forum, and took pictures with my phone as I went along.

Apparently the latest in the PowerShot line doesn’t have this problem, but I’m not one to skip a chance to vivisect a gadget. Also, the discretionary budget for electronics in Casa de Zheng is tapped out.

WARNING: This will void your warranty, might destroy your camera, yadda yadda yadda. Proceed at your own risk. Take the battery out first, so an errant slip of your screwdriver doesn’t short something in the camera.

Tinkering 101 tip: Have an ice cube tray, egg carton, or other segmented container handy to separate the screws for each step.

Also, never, ever work near a floor register. Trust me on this.

Step 1: Remove the screw next to the preview button.

Step 2: Remove the screws on the bottom of the camera.

Step 3: Remove the screws on the left side of the camera. The strap harness is a separate piece and will come off easily.

Step 4: Remove the screw on the right side of the camera, next to the AV door.

Step 5: Open the AV door and remove the screw inside.

Step 6: Gently pry open the case with a flat tool and pull the case straight back. Some fiddling may be required to get things apart. There’s a ribbon cable holding things together, so don’t yank too hard.

Step 7: Flip the little tab holding the ribbon cable in place upwards. Be gentle.

Step 8: Remove the clear plastic covering these screws, and then remove the screws. Gently pry the metal piece off, making sure to save the small L-shaped bracket on the lower left.

Here’s the the dial assembly.

Step 9: This is where the magic happens. Lift the front of the dial away from its contact pad a little bit. Don’t try to pop it off, just create some space between the two pieces. Spray your solvent into this space. I just dribbled some isopropyl alcohol in there and then rotated the dial around a bunch of times to clean out the mystery gunk that was causing my dial to fail.

Follow these steps in reverse order to reassemble. I used some packing tape to replace the plastic removed in step 8.

Getting the ribbon cable back into its socket can be a little tricky, but the rest of the case snaps back together in less than a minute.


What should my first layer look like?

February 24, 2013

Your 3D printer just arrived. The nearest hackerspace is 100 miles away. You’re all ready to start printing, but all you really know about the technology is what you’ve seen on YouTube videos and breathless reports on Wired, or the Colbert Report.

They never show you the bottom of the print in any of those venues. It’s always Stanford bunny this or Colbert head that, and that’s all well and good but there’s no one around to tell you you’re doing it wrong.

first layer

I was happily printing failbottom models for months before I went to Maker Faire in Detroit and saw a proper print done by some experts.

The stringy bottom on the first two prints is mostly caused by having an off-kilter heated build platform. Make sure your heated build platform is as level as possible before you start printing.

MakerBot Replicator 1
ABS, 240° C
HBP 110° C, with painters’ tape

(These are prints of my Magic: The Gathering Fungus Tokens.)

MakerBot’s leveling script never seems to work perfectly for me, but since I’m printing small objects anyway I just make sure the HBP is locally level in my printing footprint. There’s no need for the corners of the platform to be 100% level if the center’s good enough.

I often start a print and let it run for a single layer to let the print heads get to their destination. Then I abort the print, remove any plastic from the HBP, and use ReplicatorG’s homing function to home the Z-axis to minimum.

(In ReplicatorG, go to Machine->Control Panel and select the Homing menu to do this.)

Then it’s a matter of twiddling the thumbscrews on the HBP until the nozzle passes MakerBot’s business card test. When you slide a business card between the nozzle and the HBP and the surface of the card just catches on the nozzle, you’ve got it.

It takes some time to get a knack for it, so don’t despair. I find it works best when the nozzle makes an indented scratch along the card’s face.

The first company to ship an auto-leveling build platform gets a fistful of cash from me.

It’s possible to get a mirror-smooth base when printing on kapton, but I’m mostly printing with ABS on painters’ tape right now. More on that in a subsequent post.

Return of Kung-Fu Rat Thing

February 16, 2013

Every time I do this hand test I get just a little bit creeped out.

The Delrin Plunger

January 21, 2013

Fresh off my success clearing the left nozzle on my Replicator, the right nozzle stopped working.

So I cleaned it out with the aforementioned acetone and drilling process, and still no go. So the next thing to try is adjusting the fabled Delrin Plunger.

It sounds like Elvish plumbing equipment, but it’s just a little piece of plastic that lives inside the Replicator’s Stepstruder Mk. 8. The plunger’s job is to maintain pressure on the filament so that the stepper can feed it into the heated nozzle.

Over time the filament will wear a groove in the plunger’s head, which reduces contact between the plunger and the filament, which in turn makes it had for the drive wheel to push the filament through the nozzle.

This is what a plunger looks like after about eight months of more-or-less daily use. The blue arrow points to the wear on the head.


If filament isn’t emerging from your nozzle, or it’s coming out really slowly, rotating your plunger may help.

With a couple of hex wrenches this is a ten-minute job. Be aware that the plunger is inside a two-piece plastic case held on to the stepper by two bolts.

This is a right extruder, so the plunger goes on the left side, pointing away from the Replicator’s midline.


And then here it is with the second piece of the case attached. Note that I’ve rotated the plunger 90° so the filament has maximum contact with the plunger’s head.


When you disassemble this case be careful that the plunger and washers don’t go flying. The washers you could probably replace, but I have no idea where to get a new plunger. MakerBot’s fresh out of them.

Cleaning a Clogged Replicator Nozzle

January 19, 2013

Last week I came down with what must have been the flu, and all my creativity and motivation ebbed away like so much mucus.

So I haven’t updated the blog in a while. Thingiverse redesigned its website, which broke my /dev/random scraper script, and I’ve been so busy digging out from under a pile of flu-delayed work I haven’t had the opportunity to repair it yet.

I did manage to restore my dualstrusion Replicator to full operating condition, though. Here’s what it looks like when your nozzle gets clogged.


A little bit of filament will still emerge from the nozzle, but it’s anemic and thin and bunches up around the tip. You won’t get any prints out of this.

MakerBot’s replacement nozzles have been out of stock for as long as I’ve been looking for them (about six weeks), so it’s up to you to solve this problem yourself.

They do have some maintenance tips that will help you get the nozzle off.

I skipped the “unbolt the stepstruder” step. The nozzle unscrews easily with a wrench or pair of pliers, but be careful, that little guy is hot if you’re following the instructions.

Here’s what eight months of melted PLA/ABS gunk on the inside of a nozzle looks like, as the late, great, Toshiro Mifune intimidates the nozzle into functionality.


(I have a Yojimbo poster in my office. I think I’ve seen every Kurosawa movie at least once.)

The instructions say to leave the nozzle in acetone overnight, but I think that’s overkill and, in the case of a really clogged nozzle, probably ineffective. A combination of acetone baths and physical goop removal got mine working again.

So first, an hour in acetone. Find a container that the acetone won’t dissolve. A shot glass will work. Do not drink the acetone.


I tried a few little tools before I found one that really scraped the gunk out well. Needles and bits of wire didn’t do the job, but this small drill bit did. I just stuck the bit in and twisted back and forth; no electricity involved.

Then back in the acetone bath for an hour, and then the drill bit again. Lather, rinse repeat two or three times.


Replace the nozzle, load your filament, and before you can say Bob’s your uncle, you’re back in show-booty-bidness. I didn’t even have to recalibrate the build platform.


I’m working on a couple of dualstrusion models now. Watch this space.

Once More, With Rigor

November 29, 2012

This is a follow-up to yesterday’s post on printing with PLA, where I claimed that the orientation of the painter’s tape on the build platform is important to the stick-to-it-ive-ness of a PLA print.

But is it? Really?

A comment from CymonsGames (who’s doing some great stuff on Thingiverse, BTW) got me thinking. Is this 3d-printing feng shui, or is this a real effect? Does the grain of the painter’s tape matter? It worked once yesterday.

But anecdotes ain’t data, people. Imma test this.

I’ll try and remove as many variables as possible from the experiment, but since my basement clean room is currently occupied by an eldritch horror I’m stitching together from abattoir scraps, I’ve got my Replicator in the living room and ambient temperature control isn’t really possible. It’ll be somewhere between 64° and 69°F.

I made a special model for this print test: it’s just a 30x30x2mm solid with a raised zheng on it.

And some skeuomorphic rivets. Because, rivets.

Most importantly, this model is thin, so I can run this print a bunch of times quickly.

ReplicatorG Settings:
10% infill
.22 layer height
print 240° on first layer, 210° afterwards
HBP: 35°C

I used fresh tape before every print, all from the same roll. The first three prints were with front-to-back tape, the next three were with side-to-side tape. All tape was the same stuff, 3M Scotch 2090-1A ScotchBlue Painter’s Tape.

Minor tip: Make sure you have tape everywhere that you plan to lay down PLA, especially the homing line from the corner of the build platform to the start of the print. If you miss that little detail, your print head may end up dragging a blob of plastic all over your first surface and mess with the print.

Here are the results:

In summary: these tests don’t show much difference in stickiness with different orientations of painter’s tape.

I even mixed up the orientations just to see if I could mess up the print. No good. Every print looked more or less the same except for a little curling on front-to-back #1.

The information contained in that last post is no longer operative. Put your tape on side-to-side, front-to-back, whatever gets you through the day.

Scientific method. For great justice.

How does my toaster work?

November 25, 2012

TL;DR summary: I fixed a busted toaster in 16 minutes without burning or electrocuting myself. HUGE WIN. Also: toasters are more complicated than you’d think.

WARNING: Grody photo of a crumb-crusted toaster follows.

Our toaster stopped working a week ago, sending ripples of calamity through our breakfast routine. Then the family went away for Thanksgiving and upon our return I noticed that the toaster had failed to heal itself in our absence.

The toast wouldn’t stay down. Push the plunger, the bread pops right back up. I supposed maybe a spring had come loose, so I popped the cover off and took a look at the mechanism.

As I worked I was half-hoping that I’d screw it up badly enough that I’d need to buy a new toaster and use this one as the body for a toasterbot or something.

No springs seem to be out of place, and nothing looks bent, broken, or obviously amiss. No butter or fried mice gumming up the works, although there’s about half a pound of toast particles rattling around in there.

Ho ho, what’s this? This seems like an awful lot of electronics for something as simple as a toaster. Bears further investigation, obviously.

When the plunger’s down, the little plastic lever to the right drops a metal strip across the two contacts, completing a circuit.

And what’s up with that coil? Electricity flowing through that coil creates a magnetic field, which will keep the metal strip and in turn, the plunger, stuck in the down position.

A timer elsewhere in the unit must turn off the electromagnet when the toaster thinks the toast is ready, releasing the spring-loaded lever.

So. If the circuit were to fail, the electromagnet wouldn’t keep the plunger in the down position.

Sure enough, there was a crumb shorting out the electromagnet. A quick puff of air and she’s working again.

Twenty bucks saved.