Tuesday, May 7, 2013

Building a home workshop

My work table. The pill bottles at top left
are for storing SMD components. The adhesive
labels Digikey sends with these components
are the perfect size! 
This post is for all the serious hackers and EE majors out there who want to build cool stuff at home. Some of my friends have seen the mess that is my apartment/workshop, and began wanting to build up their own home workshop. So they ask, "What should I get first?"

To begin, you can check out a list of things I think a serious hobbyist should have on SparkFun. I am assuming that you have maybe a few basic tools, but you want to do some more advanced stuff. Of course, I'm not giving a Divine command ("Thou shalt buy a temperature-controlled soldering iron with a brass sponge and a chisel tip!"); this is just a strong recommendation.

There are some items not in that list that have to be purchased elsewhere (Sears seems to have the best combination of prices and quality at the time of this writing):

  • Mini pliers set - While Sparkfun does have some pliers, reviews have remarked negatively on their quality. Beware of cheap pliers, because their grips will rip over time, their springs can slip out, and they will get loose easily. Look for molded handles that won't rip; otherwise, if the handles are jacketed in rubberized plastic sheaths, make sure the coating is thick (~2mm, thicker is better) and hard to tear at the edges. Try to get a set with a carry case; this helps avoid losing them. Expect to pay roughly $30 for a set of five, and around $10 individually. In order of importance: long-nose, diagonal cutters, bent-nose, end cutters, flat-nose and needle-nose.
  • Wire strippers - Same warnings as the pliers set. I'm suspicious of any hand tool much less than $10, especially ones with blades. Strippers with adjustable screws are somewhat less quality-sensitive, but are harder to use than strippers with different apertures for different gauges. Look for a set that strips 30-20 AWG wire, between $12 and $30. You will probably use them more times than any other tool; get something good and rugged.
    Bad, cheap tools. The mini screwdrivers at
    left are poorly made, often too thick for the
    screws they are supposed to drive. The orange
    Torx driver was made of soft metal and
    became nearly useless, wearing down after
    about three uses. Note the broken needle file
    in the middle. And, the wire stripper/crimper
    on the right is fully closed, but there is a
    huge gap between the wire stripping
    apertures. Not to mention, the cutting
    surfaces have been painted over at the
    factory and are hardly sharp at all.
  • Screwdrivers - Medium and small ones are the most important. Again, avoid cheap brands - they are made of softer metal and will get damaged easily. They will even damage your screws. I use small screwdrivers most often, so I don't like ones with interchangeable bits - it's too fiddly for me. Medium screwdrivers, I can get away with interchangeable bits, since I use them less often. But if you have the space, drivers without interchangeable bits are the most convenient; there's less stuff to use, and it's quicker to switch between them. (And, having more than one flat head driver is great for prying things open!) Although Craftsman is not as well-known for quality these days as they used to be, screwdrivers are not as quality-critical as bladed tools or tools with moving parts; they have a decent 28-piece set that covers the medium and small screwdriver range for about $40 (they even throw in Torx drivers!).
  • A Dremel clone is useful for making project enclosures. Dremel itself is grossly overpriced, and their cheapest 7.2V battery-powered unit doesn't last long enough. Don't get ultra cheap ones (<$25), because they vibrate too much and usually aren't speed-adjustable. You NEED the continuous speed adjustment control, or you will likely break your cutting wheels and/or your project. I prefer corded models so that I don't have to fiddle with and wait for batteries. Use the slowest speed reasonable, and brace it well with both hands against your project and your workbench. Don't hold it with your fingers; use your whole fist. A reasonable speed for cutting plastic cleanly is 1mm in 3 seconds. I use a Dremel clone that has served me well for about five years. A basic unit with continuous speed control is about $30, and the price goes up to about 60 or $70 for better craftsmanship. I recommend using thicker (~2mm) cutting wheels when you are starting out; ultra fine wheels require a steadier hand, or they will break even on plastic. Of course, use safety goggles; even with safety-rated glasses and side shields, dust and shards of the cutting wheel can still get in your eyes from above or below the lenses.
  • Needle files are also useful for making project enclosures and cleaning up Dremel cuts. Beware: cheap files will break and separate easily from their handles, so don't go ultra-cheap here, either. Around $12 for a set of four or five is reasonable, and you don't need more than that. I mostly use the half-round file since it is good for straight edges and corners, and occasionally the round and flat files for widening holes.
Further notes:
Two breadboards and a jumper wire box.
The small breadboard at the right is an RF
carrier wave generator for an AM radio
transmitter. The bottom board is an AM
radio receiver and a few audio amplifier
circuits under test.
  • It's hard to have too many breadboards. I have four full-length breadboards, some of them with two columns, and I use nearly all of them all the time. 
  • If you are experienced with a soldering iron and have a temperature-controlled unit, you may prefer unleaded solder for personal health and the environment. However, it is harder to work with.
  • In my soldering iron, I use chisel tips almost exclusively. They present a wider face to the component and transfer heat more efficiently. Clean your tips as often as you can! This extends their life by preventing oxidation.
  • For tiny surfaces, and surfaces that solder just can't seem to stick to, use solder flux. It cleans off the top layer of oxidation and helps the solder wet the metal. This is a more advanced soldering technique; for a very deep understanding of the soldering process, see this video series. Even though I have been soldering for 14 years, I still learned many things from it.
  • For components (that are not in assortment kits), it's usually cheaper to shop on eBay, Digikey or Mouser. You can also get free samples from many manufacturers, like TI, Analog Devices, and even Molex. Unfortunately, many parts are not breadboard-friendly nowadays, so I'd suggest looking for a predesigned Sparkfun breakout. Failing that, you can design your own adapter boards in Eagle CAD (free to download, see the tutorial series) and send the design off to OSH Park for manufacture ($5 per square inch for three double-sided PCBs).
  • If you are doing analog and have the money, a digital storage oscilloscope is essential. The Rigol 1052e is famous for being inexpensive and easily (software-) modified to work up to 100MHz.
And finally:

Never, never shop for tools at the Dollar Store. Or anything like it. That is worth repeating: NEVER, NEVER shop for tools at the Dollar Store, or anything like it. You WILL regret it.

Happy hacking!

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