Metal Lathe

While ITP schedule gets crazier each week, subtraction class & assignments never fail to soothe! Using metal lathe was an enjoyable, satisfying and rewarding experience. Never before in the shop I was so much focused, geared up, and happier.

For the first assignment with basic lathe operations, I used a piece of 1″ aluminum rod and also tried delrin rod. I started with a piece of aluminum Immanuel was using before he finished his assignment. It was partially turned and faced and I learned a few tips from him before I started.


I faced and turned the job, which left a sharp edge around the faced circle. I used slant edge of the facing tool to make it a little blunt. Next I used the parting tool, mainly to see how it feels and how different it is from the facing tool. I made a little notch around the turned surface using parting tool:


Using a lot of oil and precaution, I tried using the turning tool to mark a rather deeper notch on the surface. Although it felt really smooth while operating, the edge has radial marks on it, like that on a knob/ wristwatch crown. This was an unexpected result and I like the effect.


Compared to aluminum, facing and turning delrin was less fun and I didn’t spend much time on it. Here are the two pieces:


Next, I used the aluminum piece to make the doo-dad. I mounted it on the chuck, used the #3 center bit first:


I struggled for a little while with the drill chuck as I wasn’t initially able to install it on the tailstock. I saw a few youtube videos and made sure it is done right before actually drilling the hole. I used 3/32, 3/16 and finally 7/32 bits to gradually drill the hole larger in diameter. Next I stopped the machine completely by pressing the red STOP button and used the tap set. Initially I tried mounting tap on the tailstock and used the wheel on right hand end of tailstock to drive the tap into the job; but somehow the tap always refused to come out. It went in when pushed into the job, but stayed inside when I turned the tailstock wheel back.


Finally I used the key and did it without using the tailstock. I thought of tapping as an operation that would require a good amount of efforts; but it was really smooth. Like Ben had rightly mentioned, this particular aluminum ‘wants to be machined’.


Next I installed the piece with the finished face inside the chuck. Parting needed more attention as there was a lot of material being removed continuously. I used lot of oil:


I used vernier calipers earlier to measure the depth of hole drilled into the piece, and therefore the hole was visible from the other side:


Next I did a little facing and tapping from this face as well. The final machined piece looks like this:



Wood joinery was an interesting assignment that made me think of the CAD and CAM process to the last detail, and I decided to make an object that has good amount of joinery. I made a crate (14″ x 10″ x 8″) from plywood.

The drawing was simple, but I had to be careful and make sure that the notches will align. The most important part was the corners where three surfaces meet together- calculations involved thickness of the material, tolerance, and length of the notches. I designed the joins so that the opposite walls are identical pieces, like the ones on left and right with handles, as shown in the drawing below. I used mirror images so that top plywood surface texture and color would show on inside of the box, and bottom surface of the plywood becomes the outside.


IMG_6927 IMG_6928

The tolerance worked perfect: the notch length is 1.98″ and corresponding indentation is 2.02″. That is NOT good enough gap for two pieces to join together without glue; but with 5 pieces and 8 edges it just perfectly worked. Next I cleaned the cutouts with sandpaper, applied glue and clamped the pieces together for a day.

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With glue, it got a little more tighter and fitting in the last piece was a little difficult, but I didn’t have to file or sand down any surface in order to join it together. A minor error was the top edge engraving on 4 walls that creates a little 0.25″ step for a lid: On longer walls I forgot to engrave the extra 0.25″ on each end to compensate for shorter wall engraving, and it looked like this:


I had to use chisel and hammer to subtract a little 0.25 x 0.25″ square.

Next I used sandpapers to clean the edges, and handheld sander tool to clean the surface. This tool was effective in almost completely removing the stains where the glue had popped out of he joints, forming a bulge after drying:


Following is the before and after image with the stains removed.


User testing: counter app

After spending a lot of time on deciding which project to work on, I picked the smartphone counter app. This project has a good incremental development over a couple of initial weeks.

I had to do some fine-tuning before going ahead with testing:
1. Designing wireframes for the complete flow, with detailed in-between screens that make navigation possible.
2. Arranging for a smartphone mockup- Thanks to Mathura for lending me a cardboard prototype!
3. Finding people who preferably have NOT been user testers to other projects: This was not crucial, but I thought it will be interesting to test it with a new tester than someone who knows the drill.

It was worth noticing how people loved the cardboard iphone and the idea of ‘paper screens’ that need to be traversed manually. Some even asked for Illustrator file so that they could make one for themselves on the laser cutter. As a designer I found it a strong opportunity to get things going with a cheerful start. I asked used to perform following tasks for testing:

  1. Add a new activity named ‘Coffee’ to the counter app.
  2. You just had a nice, refreshing coffee. Go to the app, and add one to the count.
  3. You set the goal long back, now you have it under control and you never reach the maximum limit of 10 cups a week. So go to the app and remove Coffee from your activities.


New Mockup 3


New Mockup 5


Here are some important findings from the 5 users:

  1. “It is too much effort for something that I might not want to pursue that hard.” Current design attempts making most of the smartphone features such as sharing and showing performance etc. It might make the app much lightweight and simpler, if it has minimal actionable points. The three tabs on the bottom seemed confusing to some users.
  2. Some users reported that ‘undo’ did not appear as ‘minus one’, and they spent a few seconds in determining how to correct an erroneous up count. Perhaps using big ‘+’ and ‘-‘ buttons would solve this problem.
  3. ‘Count up from 0 to 10’ was not very clear information ordering. Almost all the users found the ‘Add new activity screen’ a little overwhelming. (They either mentioned it directly, or exclaimed their reactions such as ‘whoa! what are these fields!’) . A few said they would like to keep adding coffees initially without any target for a few weeks, so as to get an idea first, on how much coffee do they really consume as of now. They didn’t know an exact or even a rough number. This had a strong connection with the physical counting object with wooden block and metal knob: a device that counts and does nothing else.
  4. Deleting ‘Coffee’ from counter menu was a little tedious. Users eventually figured it out, but they had to navigate through a few screens first to reach delete operation. I am not sure if that’s good design or not though. Keeping all user activities live for as long as possible and ‘not letting users empty their contents from the app’ seem to be deliberate design decisions in smartphone apps. For example, Facebook app demands quite some navigation for the user to reach to ‘Sign Out’ option. On the other hand they always try to make it more and more easier for the user to Sign In to facebook app, such as setting a 4-digit quick password.

These were some neutral/ good points:

  1. Mostly the users liked the idea of having all the activities together on the home page.
  2. In all the tests, users accurately inferred outcomes of clicking on a given button. Though their actions it was clear that they could figure out meanings of the items they see on the screen in a given context (exceptions: some users could not figure out the three tabs in the bottom.)
  3. Because the wireframes were black and white and did not include any images, it was not really clear that the selected image would appear in the background while inside an activity. Almost all of the users selected the ‘add image’ camera icon while creating the Coffee activity, which was a great sign. However, they never asked where the selected image would be displayed.