Modern Dining Table: Update

After not so patiently waiting 6 weeks for our table top to arrive, it is here!

As a side note, I am continually impressed at what a Prius can fit inside it.

It looks great, full of old nail holes, and patterns from the huge saw blade in the mill where it was cut many decades ago. It’s currently sitting on the cheapest saw horses I could find (Ikea, $15 on craigslist). As you may have seen in the first post, I had originally planned on making trapezoidal shaped legs from 3×1 rectangular steel tubing. However I recently came across another table that used machine stand legs from old factory equipment circa 1900:

 

Cast iron, 24 x 29 1/2 inches

 

There are a few issues with using them: hard to find, expensive (even more so to ship), and super heavy. I think I can replicate them in 3/16″ cold rolled steel which will address most of those issues. The only draw back is the texture of the metal. The originals are cast iron which has a rough textured surface from the sand it was cast in. The steel is very smooth. I’m going to see if there is some type of process I can perform on the steel to mimic the look of cast iron.

Of course switching to these legs will make the table decidedly not modern, so maybe I’ll just call it an industrial table.

DIY Mold-a-Rama Update 2

I started back up on the design of the mold machine this week. A few major changes have been made:

  • Instead of using a piston pump to move the molten plastic from the melt tank to the mold I am using an external gear oil pump. The plastic I’m using has a melt viscosity similar to that of cold oil, so the pump should be capable of transferring the plastic.
  • I have also fleshed out the melt pot mounting details and devised a new valve body that incorporates the oil pump mount. The pump is driven by a right angle gear motor. This will make the shot size easily adjustable.
  • A refill hopper, auger, and pot stirrer have been added to the rear of the machine.
  • Some of the larger subassemblies (water chiller, air tank, compressor, power supply) have been added to gauge enclosure size. I’m still shooting for coffee table sized, but finding a refrigerant based chiller the size of a shoe box is difficult. A much smaller option would be a thermoelectric (peltier) based chiller, but the heat input into the system from cooling the plastic (about 250W) and the ~2 gal water capacity is a little out of the range of most thermoelectric chillers. Not to mention they are very inefficient.

I’m going to continue to refine mounting details for a few weeks or so. In the mean time I am tracking down parts: 100rpm right angle gear motor, <1/4hp aquarium chiller, air solenoid manifold, oilless compressor, and air cylinders. Some of the parts above may change depending on what I can find at surplus shops/eBay.

Modern Dining Table: Part 1

I’ve started designing a dining table for our new apartment. I really like the aesthetic of reclaimed wood and steel tables, unfortunately a pre-made table like this costs in the $1500 to $3000 range. Way more than I can spend on a table. The designs are very simple and I figured I could make one myself. After some digging I found a local shop that will build the table top out of reclaimed douglas fir. The legs are designed by me and will be either made by myself (pending purchase of a TIG welder) or will be sub-contracted to a fabrication shop.

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Life Update

So you probably have noticed that I have not updated this website in a while. Here’s the story. After graduating in June 2010 I accepted a job offer from Samsung Austin Semiconductor. I worked in the ion implant group solving all sorts of crazy manufacturing problems that arise when you have ultra-complex multi-million dollar machines the size of a bus processing wafers with feature sizes near 30 nanometers. I got to design all kinds of fixtures and devices to help technicians rebuild and test sub-assemblies. I also worked a lot, leaving little to no time to work on my personal projects. A few months ago I got engaged and have now moved across the country to sunny California. With my new found free time (and some saved money) I have a several projects in the works that I will post here:

  • 8mm film scanner using machine vision camera
  • Small injection molder (modern day mold-a-rama)
  • Motorized shower knobs for automated temperature control
  • Arcade game coffee table
  • LED word clock
  • Updated first gen Camaro windshield motor
  • More repair tips on home electronics

Stick around, it’s going to get messy.

Automated Piston Cycler Device with Arduino

I built this control box to cycle a piston in some of our assemblies at work. We had problems with rebuilt assemblies sticking after a few hours of cycling. The rebuilders couldn’t test this because they would have to manually cycled the piston back and forth many times to verify the functionality (time-consuming). This piston cycler is capable of automatically cycling a dual action cylinder at an adjustable rate, and enable the operator to pause the motion to make adjustments, and continue testing. The counter keeps track of the number of cycles for record keeping purposes. Here’s how I made it.

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Process Control Using Arduino

This project involved designing a device to regulate the flow of chilled water through a heat exchanger based on the coolant temperature of an internal combustion engine. It’s made up of three parts: A controller, a motorized valve, and a temperature sensor.

The controller consists of an arduino, a LM298 based motor driver, resettable fuse, LCD and misc. buttons/connectors.

The motorized valve is a standard ball valve with a bracket to support a gear motor and a encoder for position feedback.

The operator inputs a desired coolant temperature which is maintained by adjusting the flow through the heat exchanger. During this project I learned about driving inductive loads with a micro controller, PID tuning, and closed loop feedback control.

How To Wash Raw Denim

So you’ve been wearing your raw denim for the last 6 to 12 months and they’re starting to smell kind of rank. Rank to the point where fabreeze won’t even cut it and people are starting to notice. Washing your raw denim for the first time can be a stressful time. Will I lose all the color? Will they shrink a size? What will happen to the sheen?

The first wash is actually kind of exciting, it’s were you get to really see the fruits of your labor. All the creases and wear patterns really pop after the first wash. Yes you will lose some dye, yes the dye will set, yes the jeans will not fade as fast. But at some point you’ve just got to wash them and move on. Another benefit of washing is that it actually increases the lifespan of your jeans. Seriously, the dirt that gets worked into your jeans through daily use actually functions like an abrasive, wearing down the fibers in the denim and weakening them. Go long enough without a wash and you’re asking for pocket holes and a blown out crotch.

I’ve heard of some pretty strange washing method on the interwebs, including wearing your jeans into the ocean, buying special japanese laundry detergent, and soaking them in a tub with shampoo. Given that some people pay upwards of $500 on a pair of raw denim jeans, I guess I can understand where all the insanity comes from. The below method does not require a beach or japanese soaps, just a laundry machine and a store bought laundry detergent.

First a before shot:

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DIY Mold-A-Rama Update

Here’s where I’m at:

 

Still many missing components and systems, most notably:  mold cooling system, pneumatics controls, part ejection cylinder, microcontroller, sensors, power supply,  mounting locations for most components, and many many more.

The pump that transfer the molten plastic is a simple piston pump using two check valves:

In my first design I created my own check valves by integrating a ball bearing and spring into the actual pump body. While this made the pump more compact, it also added several machining steps which would have increase the price. So instead I’m using off the shelf check valves that screw into the pump body. Much cheaper, much simpler, and likely to work better.

In another bit of  “don’t-redesign-the-wheel” thinking I’m using an electric deep fryer as the melting pot. Candles makers already are using this as a melting vessel. This already has a heating element and thermostat built-in, and it only costs ~$30. Compare that to several hundred dollars had I made my own vessel from stainless, used silicone band heaters, and made my own temperature regulation. The latter would have definitely been cooler looking, but for this project I’m trying to keep costs low.

Not as cool as stainless steel and band heaters.

I am at a bit of a crossroads design wise. I’m deciding between using pneumatics or electric actuators for motion control. Pneumatics are more impressive visually and give me a chance to learn about pneumatic systems (plus they make a neat pssst pssst sound), however they require an air compressor (loud) and are more expensive.  Using electric motors would make the system smaller, as I don’t need to house a compressor and air tank in the enclosure.

I’m leaning towards pneumatics provided I can find a quiet air compressor. I’ve read of people re-purposing a refrigerator compressor, but I’m concerned about their CFM rating and live span.

I’m also looking very seriously at buying a small mini mill. I should recover the cost of the machine and then some verses paying to have it done. Ideally I could find a small Chinese mini-mill on Craigslist, but I haven’t seen much out there. Maybe I’ll just break down and get this guy:

http://littlemachineshop.com/3900

Nikon D40 plastic LCD window cover repair (also D40x, D60, and others)

Most, if not all, digital cameras have some sort of plastic cover on top of the LCD. The plastic cover protects and seals the LCD from damage. If the LCD cover gets hit hard enough it cracks. If your LCD underneath looks like someone spilled ink on it, then you’re out of luck, the LCD will need to be replaced as well.

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