My itty bitty little vice for holding itty bitty little parts.

I have a mill now, but I have the problem that I need to hold itty bitty little parts still while I drill holes into the side. (Sort of like this but much smaller–about 1/4″ outer diameter, 2mm inner diameter.)

So I made myself an itty bitty little vice for holding itty bitty little parts.

IMG 3028

Drink coaster for size.

Turning on a metal lathe

So I bought a bunch of brass and aluminum to go along with my metal working lathe, and today I tried to turn a plumb bob.

And here’s what I learned.

Bob

(1) Make sure you have all the parts in the box. I took delivery of a 4 jawed chuck, only to find the screws were missing. (I went ahead and simply ordered the replacement screws; the theory being that at some point I’ll lose the existing screws anyway.)

(2) You can achieve some amazing precision on these lathes. Even a cheap lathe can cut objects to a tolerance of perhaps 0.001 inches. However, you get these precisions only with a lot of effort and thinking about how you are going to cut the part. For example, it doesn’t matter if you have tools that are accurate to 0.0001 inches, if the metal you’re cutting deflects 0.1 inches in the middle.

(3) It is impossible with three jawed chuck (or even a four jawed chuck) to flip the part and turn the length and have it all work out. (See the line in the middle of my picture above? That’s where I tried to flip the part.) Instead, you should minimize the number of times you remove the part from the chuck–and if that means turning the part down the entire length and then cutting the piece as a last step, there you go.

(4) You can, however, face the part after you cut it.

(5) I also learned I suck at cutting the part off. But I bought one of these metal cutting band saws, so it’s moot anyway.

(6) The amount of effort to cut a thread is just absurd. I think I want to put together a tool which can be used to mount the threading tools and turn them using the threading feature of the lathe. The other option is to develop more upper body strength.

(7) Brass is damned pretty.

(8) Also, the auto-feed lever is damned cool. When you think the cut is smooth, reset the cutting tool to the same depth and take another pass–and you find more material gets cut off. Wash, rinse and repeat 3 times and you get a nice finish.

I made a whole bunch of mistakes this morning, but I’m starting to appreciate both the capabilities and limitations of the lathe. I have a bunch of aluminimum stock on order from these guys so I can practice some more, and I also have a milling machine on order which I intend to practice with as well.

Ultimately my goal is to build a clock–but before I start building a clock I need to learn how to use the tools.

Evidence based data

I just saw an ad in my inbox which describes how your mouse is slowing you down, and you need to switch to using a text editor/IDE which can be completely driven by the keyboard.

And it bugged me.

It bugs me the same way all the other Shiny New Things bugs me, the way they bug Uncle Bob.

Further, it bugs me because we have some concrete evidence that this simply is not true. Meaning we have concrete evidence that (a) selecting a menu item is faster than typing a command, (b) finding a menu item is faster than using a keyboard shortcut if you haven’t committed that keyboard shortcut to muscle memory, (c) it takes a nontrivial amount of time and effort to learn the keyboard shortcut, which means that while common commands will be committed to muscle memory quickly (i.e., cut, copy and paste), less common commands are faster found on a properly structured hierarchical menu.

But no-one gives a fuck about evidence-based data anymore.

Because it gets in the way of The Churn.™

And it gets in the way of a thousand developers trying to make a name for themselves by positioning themselves as the inventor of The Next New Shiny Thing.


So do us a favor: if you design user interfaces or are thinking of The Next New Shiny Thing, get Designing With The Mind In Mind and understand how and why our brains work the way they do.

And stop treating your users like “lusers” or like Stockholm syndrom sufferers, so badly tortured by your poor design that they engage in traumatic bonding through an “ongoing cycle of abuse in which the intermittent reinforcement of reward and punishment creates powerful emotional bonds that are resistant to change.”

So at some point I decided I needed to set up a machine shop…

I’ve been making more and more things with the Form 2 printer, and I find making things quite addictive. I’ve worked some more on some gear design software for the Macintosh, and now I’m finding to make the thing I’d like to ultimately make, I need some odd-shaped parts that don’t quite fit in the printer or would be better made from other materials. (Simply buying 2mm by 100mm pins isn’t working out as well as I’d like, simply because sometimes I need different lengths or I need different shapes for the gears to properly rotate or to be properly moved or set.)

I’m not giving up on the 3D printed parts, of course, but being able to build custom cut arbors using metal for the 3d printed wheels (gears) to rotate on would be extremely helpful. And eventually doing all of this in brass and steel using the 3d printed parts as prototype shapes would be very cool.

So I ordered my first shop tool.

And it’s not what you’d expect.

I didn’t order a mini-lathe, though that is first on my list of things I want to buy. (And to be honest I’m on the fence as to if I buy a micro-lathe or something larger first. The advantage of the former: I’d be able to shape the small arbors and custom screws that I need to make my gadget with ease. The advantage of the latter: I’d be able to shape a full range of parts, including some larger components I’ll eventually want to build, including those brass gears. Eventually, of course, I’d want both.)

I didn’t order a mini-mill. (This would allow me to make many of the brackets and holders and supports my gadget will eventually need, though for the time being I can 3D print many of them.)

I didn’t even order a bandsaw, though I intend to order one when I order whatever lathe I intend to eventually get.

No, I bought one of these.


Now I’m sure you’re asking yourself “why the hell did you order a shop crane?”

Simple.

Did you see the shipping weight on some of the other gadgets that will eventually need to be positioned on my workbenches?

The HiTorque 8.5 x 20 Bench Lathe for example, has a shipping weight of 281 pounds; the machine itself is 220 pounds. Mills are worse: the Grizzly G0463 Mill/Drill has a crated weight of 445 pounds.

So the question becomes “how do you swing a 500 pound object and place it and attach it to a workbench” (rated at 3,000 pounds so we’re good there)?

Uh-huh.


Of course I’m relying on Home Depot to have the straps and hydraulic fluid which are necessary to run this crane.

One thing I plan to use this for–while I’m not using it to swing machines around the garage, of course–is to help hold stock metal in place for cutting in the bandsaw. Sure, it may be overkill for this use, but remember: a 3 inch diameter brass rod that is 48 inches long weighs 105 pounds. And frankly I’d rather swing that in place with a crane than lift it by hand. I’m not a young man anymore.

Observations on the FormLabs’ Form 2 printer.

Some observations on the FormLab’s Form 2 printer:

First, the resolution of the objects that are printed is simply amazing. I remember putting together the original Makerbot; this thing prints objects that are absolutely amazing compared to the extruded noodle of the original Makerbot print objects.

For example, I’m able to print 2 millimeter holes through a design and have them come out exactly 2 millimeters in size. I’m printing 32p gears; these are gears with 10 teeth per circumference inch and have them come out perfectly. (I tried the same thing with the original Makerbot; there is no way 32p gears could possibly have worked. Of course the current generation of Makerbots are light years ahead of the box of do-it-yourself wooden parts and gears of the original Makerbot printer.

Here are some parts I printed; they look imperfect because I roughly sanded them using 320 grit sand paper to see how well things would hold up to sanding. (You can get a much better result if you follow FormLab’s instructions.)

IMG 2825

I’m currently writing a Macintosh app which can be used to design gear chain mechanisms using spur gears; the mechanism is the top and bottom of a simple gear chain which performs a clock motion work, stacking two gears with a 12 to 1 ratio, so when one gear (attached to a minute hand) turns one full revolution, the other stacked gear (attached to an hour hand) would turn 1/2th of a revolution.

This is a test mechanism; ultimately I’m looking to design a clock, and I may write more about it in later posts.

The pins are 2mm by 25mm long pins; I was able to specify the holes to an amazing degree of accuracy. I was able to specify the holes in the corners of the frame to a 1/10th of a mm larger than the hole of a standard M3 screw. (Right now I’m waiting for some washers I ordered to insert between the gears.)

It’s stunning how great the quality of the parts printed are.


Of course this resolution and quality has a cost: time. The two frames that I printed to hold the gears (a test of the software that generates Delaunay triangles to triangulate the axle locations for my gears; the resulting frame was bigger than I wanted, so I need to tweak it) took 7 hours to print.

Yes, you read that right. Seven hours.

The four gears inside took around 4 hours to print.

But then, it makes sense. The Form 2 printer takes care to agitate and heat the resin to a consistent state; this allowed me to print some amazing items pretty much right out of the box. After each layer is printed (and each layer is 50 microns thick; about the thickness of a very thin piece of paper), the resin is agitated and the area cleared for the next layer. Needless to say for an object 3 inches tall, building up the part 50 microns at a time takes a while.

The resulting parts come out tacky. Even after bathing the parts in isopropyl alcohol for 20 minutes, the resin is not set or cured; you must allow the parts to finish curing–either in a UV light (mine is on order), or let the part rest for about a day.

Another thing to note is that while the results of using automatic scaffolding helps make the parts print correctly, sometimes with heavy objects the scaffolding can fail, causing print errors. (I tried printing a model of a manatee for my wife, only to have the flippers and head separate from the rest of the body, as the body was too heavy to hold rigid during printing. I fixed the model by gluing the pieces back together.)

Further, the automatic scaffolding algorithm can be a pain; you need to review the parts and edit the scaffolding locations. For example, the above photographed gears have a problem meshing; bits of the scaffolding got stuck between the teeth. So if you have surfaces that must be perfectly shaped and clean, you may need to edit how the scaffolding gets applied.


At some point when I get the gear design software working, I’ll publish a note here.

How to tell the difference between a Computer Science person and a Software Engineer:

What is Noam Chomsky best known for?

  • His left-wing political positions, especially his positions on the Israeli-Palestinian conflict and his position on modern capitalism.
  • His work on Transformational generative grammars, and his work on formal grammars and the Chomsky-Schützenberger hierarchy.

Sometimes it’s nice to scratch a small itch.

So I picked up a small Arduboy on Kickstarter, and I tossed together a game.

It’s cool to be playing with a device with only 2.5K of RAM (of which 1K is dedicated to an offscreen drawing bitmap), and only 32K of program space (of which about 8K or so is dedicated to the Arudboy firmware). The way you write software for such a small device is completely different than how you’d write software for a larger device with more memory.

The game is a variation on the box moving puzzle games out there; at present I have 30 levels of varying difficulty. You can download the sources for the game from GitHub.

Makes me want to get involved in the IoT, of course with better security practices than we saw here, or here.

Welcome to the wonderful world of liability.

So the next project I’m taking on requires that I carry general liability insurance. And one of the requirements of the general liability insurances was to take down and stop selling E6B software for pilots.

Great.

Well, it’s not like I sold a lot of copies of the software to the public. And heck, the Android version wasn’t even active; the software had been taken down from the Play store because I forgot to renew some contracts with Google Play.

But it is a shame that something like that cannot be offered to the public.


I’ve got a couple of weeks; I’ll probably publish all of the code open source on my personal GitHub account instead, because why not?

Two Factor Authentication

Credential Stealing as an Attack Vector

Basically if someone can steal your password, they often can get into your system and do a lot of damage.


A quick review: authentication “factors” involve who you are, what you know, and what you have. A one-factor authentication technique involves just one of these three things: a key to your front door involves what you have, a password involves what you know. We can bolster the strength of any of these “factors” by requiring longer passwords or better designed keys and key locks, but you only have one thing to bypass to get into the system.

For “two factor” authentication to work, it involves two of these three factors: routinely it involves “what you have” and “what you know.” So your ATM card is a two-factor system: you must first present your ATM card, then enter your password PIN.

What makes two factor authentication more powerful is that now you have two systems (working on concert) to bypass. This also allows you to weaken one factor if the other factor must also be present–such as an ATM PIN which is an easily guessable 4 to 6 digit number.


The nice thing about cell phones is that it easily allows us to distribute software that allows your cell phone to participate in the login process: making “what you have” your cell phone as part of the login process.

And there are a number of applications out there which can be used as part of a two-factor authentication process, such as Google Authenticator, which implements TOTP and HOTP one-time passwords. It should also be relatively easy to implement your own one-time password application, though ideally unless you know what you’re doing, just download and drop in the libraries from someone else’s implementation.

One way to secure your communications…

Security is, in part, about making it more expensive for a hacker to crack your system and obtain secure information.

Yesterday I noted that just because you wrap your protocol in SSL/TLS doesn’t make it secure.

Today I’ve been playing with Diffie-Hellman key exchange, using the 1024 Bit MODP key from RFC 4306 as the constants G and P in the algorithm described in the Wikipedia article. I’ve implemented this in Java using BigInteger, in code that compiles using GWT to compile to Javascript, in order to secure a conversation between a web front end and a server back end. The resulting key generated by the Diffie-Hellman exchange is used to seed a Blowfish encryption scheme which also compiles to GWT; packets are thus encoded using Blowfish and the shared secret from a DH exchange, then sent wrapped in JSON using Base64 encoding.

And just now I got the whole thing to work: I know have secure packets between a web client and a web server back-end.

That is the sort of stuff that makes me happy.