Thursday, May 23, 2013

FJ Cruiser: The Platform Begins...

My current effort on fixing up the FJ Cruiser is focused on building a platform where the back seats used to be.  This platform will serve two purposes.  First, it provides a level, flat, and elevated place for the dogs to sit behind us at the right height for them to see around.  Second, under the platform is a handy-dandy storage space for tools, winch supplies, etc.

The platform needs to be sturdy and rigid, and strong enough to handle any kind of stress we might put on it while offroading.  I came up with a design that relies on 1/2" thick marine-grade plywood (this means it has no voids on the internal plies) and 1" angle iron to join the pieces.  So far I've fabricated the fore and aft bulkheads, and a port and starboard rib – the basic strength components of the design.  All four of these pieces are bolted directly to factory threaded holes, the same places that the back seats and seat belts were attached.  The pictures below, with their captions, tell the story of what I've done so far (there's much more to go!)...

My "baby" drill press - primitive, but it works surprisingly well.  Curls are from drilling holes in steel angle irons; oil is used to lubricate the drill bit (to keep it from getting hot).

A cut, ground, wire-brushed, and drilled piece of angle iron, forming one "connector" between two pieces of plywood.

Four identical connectors (for connecting the aft bulkhead to the port and starboard ribs).

Two pieces cut from a 10' length of angle iron.

Rough-cut ends.

In the little "pony" vise, ready for grinding...

Yours truly, all gussied up with safety gear: face shield (I'm quite attached to my vision), hearing protectors (ditto), and gloves (those metal shaving and sparks can be very painful and hard to extract!).  The Australian bush hat is there to protect the top of my head from the sun!

The 4.5" angle grinder, armed with grinding wheel, ready to go to work.

What it looks like after grinding - flat end, chamfered edges.

After grinding, I degreased them with this magic stuff.  Probably should have done that before grinding!

Change over to the wire brush, which cleans all the non-grease gunk off the metal.  It also acts like fine emery paper, polishing off all the rough bits.

Quite a difference after being cleaned up!

All three parts completely cleaned up.

Next step is to mark where the holes are to be drilled.  The machinist's square does the measuring, the scribe (long pointy thing) scores lines in the metal, and the automatic center punch (short pointy thing) makes precise little dents in the metal, right where I want the center of the holes to be.

You can see two of the dents made by the center punch, and the scribed line they are on.

Connector ready for drilling, a drop of oil on the center punch dent.

First step is to very lightly "tap" the drill against the work, to check whether you've got the bit centered over the dent.  When you get it right, you can see a faint disk drilled out around the dent (as above).  Sometimes it takes me four or five tries to get the drill in the right place :)

We're at the right place, so it's time to start drilling.  The key with drilling into hard metal like steel is to go slow and let the tool do the work.  I just keep a steady pressure of a few pounds on the drill press handle.  The drill bit does the rest; takes about 60 seconds or so to drill the complete hole.  Above is what it looks like when the hole first gets started.

Here the entire width of the hole is started.  The little curls of steel are what it should look like if your bit is sharp and you have the right pressure on the drill bit.  Time for some more lubrication; don't want my bit to get hot...

The hole is finished, and you can see there are a number of quite large curls lying out.  That's what you want it to look like!  For a 5/16" hole (as above) through 1/8" steel (as above), I generally pause twice for additional lubrication.  For a bigger hole or thicker metal, I'd pause more.  It's all about keeping that drill bit cool, which will keep it sharp much longer (it gets softer when it gets hot).

Done, and degreased again!

Now I need to cut the port rib (the starboard rib is the piece with the angle iron bolted to it, lying down to the left of the router).  I use the router (upside down on the plywood) to do the cutting, not a saw - saws tend to splinter the top side of the wood, plus it's a challenge to make a perfectly square cut with them.  The router against a straight edge (like the big aluminum one above) makes a perfectly square cut every time, with no splinters.  It's a little tricky to control (and I screw up sometimes), but on the whole the result is superior to what I can do with a circular saw.

The router, close up, showing the milling bit (1/4" diameter).  Note the drill-like flutes to pull the wood chips up and out of the cut - key to this technique working.  The router is still upside-down, of course.

Here's my starting piece of wood, with the cuts I need to make marked on it in pencil.  There are five cuts altogether - three horizontal, one vertical, and one angled.

To make the first horizontal cut, first I set up (and clamp) the straight edge exactly 2 7/8" from where I want to cut.

All rigged for cutting.

The first horizontal cut.  Note I first cut through some waste wood to get there.

The second horizontal cut.

The third horizontal cut.

The angle cut (note some of the waste wood now fell off).

And the last cut, the vertical cut.  My piece is done.

And there it is!

Marking hole centers with a scratch awl.

These two holes are getting a counter-sunk bolt in them, so I drill them with the special counter-sink drill bit.

The trick is to counter sink them enough so that the head of the bolt projects ever-so-slightly (perhaps 1/32"), so that when you tighten the bolt, it pulls in flush with the wood.  There's a bit of art to this, as it depends on the size of the bolt and the kind of wood...

The rest of the holes are just 1/4" holes for bolts; there's steel on both sides so no counter-sinking is required.  To make a nice, clean, perfectly cylindrical hole I use a special kind of bit called a Fortsner bit - with a "backer board" so that the bottom of the hole doesn't splinter.  The backer board is just a piece of waste wood placed below the work piece when you're drilling.  The drill bit goes cleanly through the work piece and 1/8" or so into the backer board. 

The Fortsner bit.
Tah dah!  The perfect resulting holes...

The port and starboard ribs, with all their connectors installed.  The two long connectors tie into the fore and aft bulkheads; the short connector on the bottom ties directly into the FJ.

Lunch Yesterday...

Debbie and I went to lunch yesterday with a friend and former colleague, Aleck L. – at Sushi Ota in Pacific Beach.  It was make-your-brains-fall-out good, and it was even better to spend some time with Aleck.  This was my lunch, a daily special:

Debbie ordered several rolls and gobbled them down like Mo'i attacks dog food.  Then we had dessert – green tea creme brulee, also delicious.  After we ate, we sat and had a delightful conversation in which three hours went by without our noticing...

Murphy's Law...

Dave Carter, over at Ricochet, waxes poetic about his personal encounter with Murphy's Law the other day.  Here's one paragraph to whet your appetite:
As it turned out, the remainder of THAT day was filled with one human abnormality after another.  It began to wear on me, so that by the end of the day, I sought out a booth in the corner of the restaurant, as far away from everyone as possible.  That was when, predictably, a very large fellow and his wife arrived at the booth directly behind me.  When the big fellow -- we'll call him Jabba the Customer -- plopped down in the seat directly behind me, it had a seesaw effect that nearly launched me across the room.  I tried to make the best of it though, honestly I did.  When he decided to blow his nose loud and long in the restaurant, it sounded like the contents of his head were being spackled into his hanky.  I didn't say word, though my appetite was waning.  But when he followed up that little display of grace with a chunky, wide open-mouthed belch, I quite reflexively turned around and asked, "Would you like me to get a waitress to clean that up or do you want to barf first?"  His wife sat there wide-eyed and speechless, and Jabba the Customer didn't even acknowledge that I had said anything.  A few minutes later, they left. 
The rest is here...

Key Management Is the Problem...

In any system for transmitting messages using encryption, the security of the system boils down to the security of the encryption key.  This key security often isn't electronic at all – you need a secure way to distribute keys to authorized message senders and receivers.  If that key is stolen or misplaced, your key distribution process and ensure that no real messages are sent with that key – as the bad guys might have it.  This process is called “key management”, and it's hard.  Almost always there's a flaw in key management – anything from a minor and unlikely vulnerability to a gaping security hole you could drive an aircraft carrier through.  All of this is well understood by anyone designing a security messaging system. do you make a secure key management system?

Well, Roarke Horstmeyer at the California Institute of Technology and some others think they have an answer.  For their “key” they use a slab of special glass whose microscopic structure is random, unpredictable, and readable.  To set up a secure system, they make two slabs of glass – one for each side of the messaging system.  They then read the random data in each key and combine them to make a public key.  This public key can be safely published to the world, as it's contents can't be used for anything by itself – you have to possess one of the two glass slabs to make it useful.

Let's say we have two parties: the traditional Alice and Bob, each of whom have one of these special glass slabs.  The combination has been published.  Now Alice wants to send Bob an encrypted message.  She figures out how long her message is (“n” bits) and then takes the next “n” bits of her key (read from her glass slab) and uses them to encrypt her message.  She sends the message to Bob.  Bob takes the next “n” bits of his key (read from his glass slab) and subtracts it from the published combined key, yielding Alice's key – which he then uses to decrypt her message.  Straightforward and as secure as a one-time pad.

Really the glass slabs are just a memory – a very reliable, physical and tangible memory that (today at least) could not easily be copied.  Even just reading it would take a considerable amount of time, which means that security protocols (processes) could detect the fact that someone was reading it.  There's nothing special about the glass per se; it's this combination of characteristics that make it attractive.  A thumb drive could store data for a key, and be used the same way as the glass – but copying the thumb drive takes only a few seconds, and it's easy.  A thumb drive (or any other electronic store) would be vulnerable to any such attack.

The trouble with the glass, though, is that almost certainly there's a technical attack – some way that a bad guy could quickly read it.  Any conceivable storage mechanism for a key has this problem...

What a Great Idea!


When you distrust your government, you start looking at things in a different light. 

Consider this: on March 31st, 2010, Colleen Kelly visited with President Obama.  Kelly was the president of the National Treasury Employees Union – a virulently anti-Tea Party group that happens to represent most IRS employees.  Nothing suspicious about this visit; that's exactly the kind of friendly visitor you'd expect Obama to have.  But...the very next day IRS workers started targeting conservative and Tea Party groups.

Coincidence?  Hmmm...