30 March 2008

Single-serving tools

Every so often, you find yourself in need of a unique tool to fit the situation. Most of the time, such a tool can be bought. Though, because of their limited need, stores must sell these for a higher price to average out the lesser demand. Compounding this fact, no one wants to pay a lot for a tool they'll only use once.

I've collected a list of all the one-time, single-serving tools from recent memory. If you have similar single-serving tools, I'd like to see them.

Improvised Headset Press(1) An improvised headset press.

I needed to install the bearing cups to a 1-1/8" threadless headset on the bicycle I was building. But, I was only going to do this one time, so I didn't feel like buying a tool, even if it only cost $20.

My solution was this. A 1/2" screw is used to push two soft plastic plates together. These, in turn, push the cups into the headset. The plates were made out of some plastic from an old cutting board.

For best results, stick the cups in the freezer for half an hour--they will contract slightly and fit more easily.

Have you ever needed a really long allen wrench? [1/2](2) An exceptionally long allen wrench.

Have you ever needed a really long allen wrench? Well, I did when I was constructing the drawer set for my new lathe. Local hardware stores didn't sell allen wrenches this long--at least not in metric--so I built my own.

Take a normal allen wrench and hacksaw-off the bend. It's hardened steel, so it will mess up your blade--use a worn-out blade. Take a length of 3/8 round steel, bore a 1/4" hole at one end, at least 1/2" deep. Insert the hex bit, and then weld it on to the rod.

Have you ever needed a really long allen wrench? [2/2]Also, bend the far end of the rod, or weld on some sort of handle. I used my lathe to turn the rod down a bit, making it easier to bend.

Ultimately, this 5mm wrench will reach more than nine inches deep into a 1/2" hole.

Need a way to measure angles?(3) An easy way to measure angles.

When I moved into my apartment, I immediately devised a plan to build an long shelf above head level in the hallway. Because this apartment had been sliced off of a single family residence, it had an awkward hallway in the wrong place. The hallway space seems like a significant fraction of my apartment, and without the shelf it would all be lost.

The problem was that the walls in this hallway didn't meet at right angles. It's very ad-hoc, with three turns at angles around 13-31 degrees. I needed to measure these angles or the wood wouldn't meet right.

Sure, protractors are cheap, but one wasn't available when I had my inspiration.

I built this out of some 1" extruded aluminum angle-stock and a small machine screw, nut an washers. The trick? A hole is drilled on each bar, 3.5" from the pivot point. For any angle, the two holes and the pivot point make an isosceles triangle. Then, if I measure the distance "h" between those two holes, I can calculate the angle between those bars as 2 * sin ( h / 7 ).

The shelves, by the way, look great and line up perfectly.

So, anyone else have single-serving tools to share?

25 March 2008

My minilathe, and several mods thereof

It's been a while. There are various excuses for that, but the main excuse is that I've been putting in long days at my new job.

Lathe has arrivedThe big news (on the diy/hacking/modding front) is the arrival of my minilathe. I had been dreaming about owning a minilathe for a long time. I had always been frustrated by the cost and accessibility of various machine parts; to me, it's torture when you have a great idea and no way to build it. I looked forward to all of the rights and responsibilities given to lathe owners.

This lathe is just one brand of a common chinese lathe, sold by Cummins, Harbor Freight, Grizzly, and others.
One benefit of this oft rebranded tool is that many online communities have sprung up about how to use or modify it, for example the right-wing 7x10 minilathe group. However, the Cummins model is in a class by itself. It is simultaneously the cheapest, and shipped with the most accessories, including a faceplate, a 3-jaw chuck with both internal and external jaws, 5 HSS tool bits, a tailstock chuck, a dead center, a set of change gears, a steady rest and a follower rest. It is a great value.

Let me first say that, despite the limitations inherent to small lathe, this lathe is quality. Every moving part has a gib or some other way to adjust it. Although each part may slowly wear out, the designers have provided the end user with a way to compensate.

Let's compare it to the famous Sherline Mini-lathes. Among hobby machinists, Sherlines have a good reputation for quality, and are comparable to my Cummins in size. However, Sherlines do not include change gears and a feed screw -- necessities for cutting internal / external threads -- nor do they include a compound slide, thus one cannot cut bevels. Oh yeah, Sherlines cost more too.

Lathe has arrivedEnough about comparisons, on to the juicy stuff. I unpacked the lathe. The first thing you need to do with a machine like this is take it apart. I took it down to it's solid pieces, cleaned off the factory grease, re-greased. re-assembled and adjusted it. These preliminaries are critical, since they give you a good understanding of how the machine all works, and yield a certain confidence toward using or modifying the machine.

Lathe Mod #1So, what modifications have I done? First the simple shit: I removed and recycled the two chip guards. Then, I removed the plastic do-hickey covering the emergency stop button. Perhaps I'm misunderstanding it, but it seems much safer to have a clear path between my left hand and the stop button. Additionally, I replaced the bolts that secured the hand wheels, since they tended to hit my knucles.

Lathe Mod #2aNext, I grabbed some strong magnets pulled from a scrap hard drive, and used them to keep track of the various chucks. I find that the use of a magnet is just slightly entertaining, perhaps only on the subconscious level, but that is enough that I never forget to replace the key. I don't imagine I'll ever accidentally leave it in the chuck.

Lathe Mod #3I don't own a grinder with which I can grind my tool bits, but I can put a small arbor-mounted grinding wheel in my lathe. The beauty of this is that I can use my lathe's compound slide to get a precise angle onto the tool bits. Similarly, I realized that I can use fragments of hackway blades to shim-up the cutting tool.

Lathe Mod #5My lathe came with a lot of accessories, and suddenly I had nowhere to keep them all, let alone work. So, I went to work building a drawer set. I collected a bunch of scrap wood and plastic from around the neighborhood (and trash day in Brooklyn contains enough wood to build a few houses, I'm sure). The drawer set is sturdy as hell. I added in a few solid brass drawer pulls that I found at the Park Slope Flea Market to finish the effect. So much of this sort of improvised building involves moments of inspiration. This simple allen wrench holder is one such example.

Most recently, I built a apron chip guard, inspired by the one that Varmint Al made. One failing of the minilathe design is that it leaves the gears behind the apron exposed, and poised to collect metal chips from the cutting action. As Jobst Brandt once said, "Commercial abrasive grinding paste is made of oil and silicon dioxide," and so I was concerned about these chips, even though the gears were otherwise greased. So, here is how I built it:

Lathe mob #7 [1/6]Cut a sheet of 1/8"-thick pastic to the rough contours of the lathe's apron. I used some plastic that used to be part of a printer's enclosure. Drill a hole large enough for the gear's shaft (I cut mine 7/8" since I had that bit available, though smaller would do). Drill and countersink five holes around the perimiter of the chip guard.

Lathe mob #7 [2/6]Transfer those holes from the plastic chip guard onto the back side of the apron using a center punch. Drill and tap those holes. I used a #36 drill, and a 6-32 tap, though anything of similar size will work. The apron is made of cast iron, which is a surpisingly soft metal. Nonetheless, proceed with caution so you don't break your tap, and use lot's of wd40.

Lathe mob #7 [3/6]This is a view of the back side of the apron after the five holes have been drilled and tapped.

Lathe mob #7 [4/6]Clean out all metal chips from the area, and re-install the gears.

Lathe mob #7 [5/6]Drench the gears in a heavy grease. I used an old hacksaw blade as a spatula to really muck it into the nooks and crannies.

Lathe mob #7 [6/6]Install the chip guard. It is secured down by five 6-32 machine screws. Re-install the apron onto the lathe, and rejoice in your apron's newfound ability to repel chips!

07 March 2008

Multi-color lamp from (some) reused materials

I've seen this style of fabric-draped, muted-light lamp all over new york recently. I decided to build my own, and make it glow funny colors.

Lamp schematicThe schematic is really simple; I wanted to keep it that way. A PIC16 is used to create three PWM signals. Those three signals feed into three NPN transistors to drive a stack of colored LEDs. I proper design would use resistors both at the base and the emitter, but I was lazy last night.

Also, this thing has source code.

Lamp Board - Obverse
Tryin' to keep it simple. I put it on some perf board, and wire wrapped it. I tried to space the LEDs evenly on both sides of the board. The obverse:

Lamp Board - ReverseAnd the reverse.

Lamp wire-frame
Then, I made a frame out of two coat hangers. I wrapped them with some packaging material from my new job's recent Ikea visit, and sewed it on.

Lamp ShadeIt starts to look a little bit better as more sewing is done.

Finally, it looks like this in the dark:

03 March 2008

Last minute notice: Free class on TIG Welding tomorrow

Christian just told me that 123 Tompkins Community Space (map) is offering a free workshop on TIG welding Tomorrow, 4 March 2008, at noon-o-clock. I don't think I can make it (see note about new job in previous post), but I wish I could. Why?

Well, I say that I know how to weld, by which I mean I can use an oxy-acetaline kit, and I can use a MIG welder. Still, that limits me to steel. TIG welding, on the other hand, can be used to weld a greater variety of metals, such as aluminum, magnesium, copper, and alloys thereof. If you're interesting in bicycle frame building, for instance, this is the kind of welding you want to learn (in addition, of course, to brazing).

Additionally, I'll plug this by reminding everyone that it's free, rare for anything educational in NYC. Show up, enjoy it, and... you know, leave a donation if you have fun.

It's been too long

My appologies for taking a week or so off from the blog. I assure you there is more to come. Here are some of my excuses for slacking on the blog:

I have started a new job, where I work as a Java developer, though so far our work has mostly been assembling Ikea furniture. The office is awesome--on vibrant Franklin Ave in Crown Heights, Brooklyn. I like how every five minutes or so someone stops by to ask "so, what is this place?" Apparently, the office was an abandoned/condemned building for many years, and though people are glad it's no longer rat infested, the neighborhood really wants another restaurant, lounge, or other public space. The job has been keeping me busy, but in a good way.

I've heard from a few Graduate schools. What? I forgot to mention that I applied to a few PhD in CS programs? Yeah, I did.

So far, Princeton has made me a good offer, and CMU and UPenn have rejected me. More schools are pending. At the moment, it looks like I'll be moving to small town Jersey unless Columbia wants me. On a related note: does anyone out there live in Princeton? What do you think of it? Of particular interest to me are cultural events, bike-friendliness, a leftish-leaning populace, and urbanity (ha!).

I purchased this lathe today, and am looking forward to its arrival. As far as metal lathes are concerned, this one is dirt cheap (though still an expensive tool). I plan to fit this into the cheaphack mission by working with scrap materials. I anticipate my first project will be a crank puller, followed by fancy brass crank bolts and top bolts, working my way into Stirling engines. Don't worry, you will be posted.

I have two projects on the way: a stylish lamp made from recycled materials, and a bicycle generator built with an old air conditioner. Stay tuned for more absolutely cheap diy technology.