Monday, December 31, 2012

Updated desk plans

Recently I discovered and was inspired by Matthias Wandel's amazing Sketchup plans.  He sells some of the more complicated ones (and I think they are well worth the price) and offers others for free on his website.  The great part of his plans is that not only are they 3D models of the project, but by utilizing the features of Sketchup they are also excellent instructions for constructing the project.

I did a little analysis of one of his plans to try and figure out how he does it.  I found that he uses three important features of Sketchup to create his plans:

  1. Components: Componentizing pieces of a model makes it easy to organize the model but also much simpler to highlight specific parts of the model.  Matthias seems to organize components based on how things are organized in the real world.  For example, a table leg or drawer would each be a component.
  2. Scenes: In Sketchup it's easy to record a given camera viewpoint (among other properties), and this is called a scene.  Matthias' plans use scenes to hide various parts of the model and highlight individual construction or assembly steps.
  3. Layers: These are used to add text and dimensions that would clutter the model if they were all visible at once.  The hidden or visible nature of a layer can be recorded as a property of a scene.

I already knew the basics of using Sketchup but I decided to try out some of Matthias' techniques to improve an existing model that I created for the writing desk I built for my wife.  I already had a completed model, so I set out to organize the model as a series of components and add scenes and layers to illustrate the construction process.

I'm really happy with the results although it took me many hours to complete the new Sketchup model. I would like to do this for my arcade as well, though that would take far longer to complete.

I still haven't found a way to host the Sketchup file (at least not a way that I like), but in the meantime I exported a video of the various scenes from Sketchup.  The resolution doesn't really do it justice and for some reason the YouTube import cut a few frames here and there which makes the video stutter, but at least it will give you an idea of what it looks like.

Sunday, December 23, 2012

Turning an arm lamp into a camera mount

I want to dabble with making some videos of some of my projects, but I don't have much in the way of video equipment.  I do have a decent point-and-shoot camera which can take video, but I don't have a tripod or anything decent to hold the camera.

Since I don't want to invest much money in this endeavor at first, I started thinking about things I could use that I already had that might work.  I have a really old arm lamp from my college days that was in sad shape but still had a decent arm.  The lamp part of it was messed up; I replaced a broken switch on the top of the lamp with a slide switch and tried to insulate it with electrical tape.  Eventually the electrical tape came off and I shocked myself many times while trying to turn on the lamp in the dark.  Here's how I turned it into a camera arm.
An old arm lamp.  Note the sketchy soldered on switch on the top of the lamp shade.

The first step was to remove the lamp.  The lamp shade was attached to the arm via two rivets.  I drilled through those easily enough and the lamp came free.  Next, the lamp cord was threaded through the hollow parts of the arm so I pulled the cord out.  That left me with just the bare arm itself.

The arm lamp minus the lamp parts.

The next problem was that the mounting plate that had previously been riveted to the lamp shade was curved and I needed it to be flat to allow mounting a camera platform.  I used a large C clamp to squeeze the plate into shape.  This worked surprisingly well and only took a few minutes.

Flattening the mounting plate.

I knew there was usually a screw hole in the bottom of most cameras and after a bit of googling it looks like most of the screw holes are 1/4"-20.  I had several bolts available of the right size and ended up choosing one that was about 1.5 inches in length and with thumb knurls so I could grip it without tools. My next worry was that I didn't want to damage the camera  by bottoming out the bolt in the screw hole by screwing it in too far.  To address this I got a wing nut to use to tighten the bolt to the bottom of the camera mount.

To mount a camera you put the camera on the top of the mount plate and screw the bolt in a few turns through the mounting hole.  Next tighten the wing nut up to the bottom of the camera mount plate until the camera is secure.  You can see how this looks in the picture below.

The first camera mount plate.

The final camera mount with bubble level attached.  Note that the wing nut in this photo is mounted on the other side of the mount plate when there is a camera attached.

The camera mount plate is pretty simple.  I went through two iterations before I got it the way I wanted.  It consists of a block of scrap wood with a few pilot holes drilled for the arm mount plate, and a larger hole for the bolt to pass through.

I thought it would be nice to put a bubble level on the camera platform to aid in leveling the camera.  I found a bubble level at Lowe's like these for a few bucks.  The ones I got had plastic hooks on each end so that they could hang from a string.  I cut off the excess plastic from the level and hot glued it to the side of the camera mount platform, taking care to make sure it was parallel with the surface that the camera would rest on.

The arm mounted on a stool with a camera attached.

The whole project took less than an hour and about $2 for the bubble level.  I already had the lamp on hand but if I hadn't I probably would have gotten this one from IKEA for another $9.  I'll be running the camera arm through its paces in the coming weeks, and if things go well you may start seeing project videos on this blog.

Saturday, December 22, 2012

Fridge Repair

A couple of years ago the water dispenser in my refrigerator started leaking.  At the same time I also found that ice was plugging up the chute that allows water into the ice maker; whenever water was dispensed into the ice maker it would hit the ice plug in the chute and shoot water all over the freezer.  So that was fun.

After a bit of quality time spent with Lady Internet, I found that these symptoms point to a bad solenoid valve where the water comes into the fridge.  Basically, the solenoid slowly goes bad which lets a small amount of water leak out of the water dispenser and into the freezer compartment which slowly freezes and plugs up the water inlet to the ice maker.

So I jumped on my favorite appliance parts website Appliance Parts Pros, and ordered this part.

This part was pretty cool in that it came with an info sheet from the manufacturer that showed exactly how to install it.  That was a pleasant surprise since usually you're left to your own devices in figuring out how to replace the part.

I got it installed in about 30 minutes and then my water dispenser started working again.  I still had to remove the ice maker and thaw out all of the ice that had accumulated everywhere, but after some work chipping away the ice and re-installing the ice maker I had that working too.

I also came away from this really impressed with the design of ice makers.  They're compact and efficient and are really ingenious.  Here's an article that talks about how they work (almost all ice makers use the same design).  The article also has a really cool animation that shows how it works graphically.

Closeup of the old solenoid valve

Aren't these awkward angles great? This is the bottom back corner of the fridge where the water solenoid lives

Friday, December 21, 2012

Washing Machine Repair

Not long ago my washing machine stopped working.  When I pressed any buttons on the control panel it would just beep at me and do nothing.

After some internet research I came across a service manual for my model of washing machine, a Whirlpool Calypso.  The manual had a nice troubleshooting guide showed me how to check the control panel with a multimeter to see if there was a button out.  The manual also showed how to get access to the control panel (shove a putty knife in the crevice where the control panel meets the body of the washing machine and pop the spring clips).

I ohmed out the control panel according the to the service manual and sure enough it was bad.  I ordered a new one from Appliance Parts Pros. It was kind of expensive, but much cheaper than a new washer so I decided to roll the dice and order it.

The service manual was really good about having procedures for testing things and had procedures for replacing many components like the control boards and motors and things but it didn't have a procedure for replacing the control panel.  

The hardest part was removing the old panel.  First I had to wrestle witht he plastic end caps that bookend the control panel.  Then I found that the bar which holds up the circuit boards you can see in the picture below was glued to the back of the control panel.  I pulled out my trusty putty knife again and used it to pry the control panel free.  Luckily it wasn't very strong glue and it came free pretty easily once I got it started with the putty knife.

Once I had the old panel removed putting the new one in was as simple as putting the end caps back on, connecting a ribbon cable to the control board, and reversing the rest of the disassembly.

And luckily the washing machine started working again as soon as I re-connected power.

The inside of the control panel after a bit of disassembly

Back side of the new display panel

Good as new

Droid Incredible Repair

A few months ago the screen on my wife's Droid Incredible got cracked.  Rather than invest in a new phone I decided I'd try and replace the touchscreen with something like this.  I watched a YouTube video on how to do it here and jumped in.

I was nervous as hell while I did it; it really felt like I was performing surgery.  In the end I was successful and saved a bundle of money in the process.

Here's some tips I learned that seemed to help:
  1. Use a hair dryer to heat up the adhesive that attaches the touchscreen glass to the phone's frame.  It helps it peel off much more easily.
  2. Use powder-less rubber gloves when handling the screen since this will help avoid getting fingerprints between the touchscreen and the LCD where you can't clean them off after reassembling the phone.
  3. Work on a clean flat table and have some container to put all the tiny screws and other parts so they don't roll away and get lost.
  4. Take your time.

Udacity: Web Application Engineering

I was pretty excited when Udacity was introduced.  It seems like a really great idea for democratizing education (though they were't the first to come up with these ideas).

I decided to take the course they offered on Web Application Engineering.  I had two goals: 1) Try out the Udacity education model and 2) Gain knowledge in web apps for help with automating my house.  

Overall I was very impressed with the course.  I took the first offering of the course and even with it being the first time they had done the course it went very smoothly.  They got Steve Huffman (of Redit and Hipmunk fame) to teach the class which was pretty impressive since it's someone that has put together a successful real-world website.

The course was 7 weeks long.  Each week there was a lecture with interactive questions interspersed every few minutes to check for understanding.  The lectures were recorded so you could do them anytime they were convenient.

Each week there was also a homework which reinforced the concepts from the lecture.  For the Web Applications course used the Google App Engine for development which worked pretty well and was a good way to make web app hosting available to large numbers of students.  We also use the python version of the Google App Engine which was nice since I really like python.

They didn't enforce that the homeworks be done in the week they were given but I'd highly recommend that you do them that way since the lectures and homeworks can really pile up otherwise.  In this way, it was like a normal college engineering course.  On average each week took me about 4 hours or so.  The homeworks were actually tested in an automated fashion by having a standard web interface for each one.  This really gave incentive for getting everything to work; if they hasn't graded the homework I would have been tempted to just say "Bah, I understand, no need to do the homework...".

At the end of the course there was a final project which was a wiki style webpage from scratch.  It required integrating everything you'd learned in the course and was a really nice way to wrap everything up.

Overall the course was very well done and I would take another course on Udacity without hesitation.  This gives me hope for the future of education.

Custom tools made from wood

Recently I was trying to debug my dishwasher.  It was leaving crusty deposits of food particles and leftover detergent on all the glasses.  It was pretty nasty.

I wanted to eliminate the possibility that there were just some leftover bits in the dishwasher that kept getting re-deposited on the dishes, so I took apart as much of the dishwasher as possible to clean out all the nooks and crannies.

When I got to the spray arm I was able to unscrew the whole thing by twisting the bottom post counter-clockwise.  But this took the entire spray arm assembly loose and I couldn't really get to the inside of the arm where I could see there was plenty of caked-on dishwasher detergent.  I'll spare you pictures of the gunk since it's kind of gross.

I noticed that the central top portion of the spray arm looked like it should detach but there was nothing that would allow me to grip it except for 4 small plastic posts.  I knew if I tried to grip these with pliers or something I would just shred the plastic and ruin it.

So I thought I might be able to fashion something that would act as a custom wrench of sorts.  I decided to try it with wood since I have lots of scrap wood available and the tools to work it.

I started by putting some blue chalk dust on the ends of each of the 4 plastic posts, then I pressed a chunk of 2x4 against the posts to transfer the marks.  Then I went to the drill press and drilled holes where the chalk marks were on the 2x4.  I noticed that there's a raised area in the middle so I used a forstner bit to drill out a recess in the 2x4 to fit.

I then tried it and it slid right over the posts and with a small clockwise twist the central part of the spray arm lifted free.  Pictures of all of this are below.

So it goes to show if you're resourceful you can fashion your own custom tools, even if all you have available is an ugly chunk of wood.

Dishwasher spray arm.  Note the 4 plastic posts on the central portion.  That's what we'll use to turn the  center part.

Here's the "wrench" after machining the holes in the correct locations.

The "wrench" fits right on top

After turning the tool about half a turn clockwise the center portion detaches from the spray arm!