obligatory obscure reference

We upgraded our Droids to 2.2 today, and while one upgrade went fine, the other went not so fine. As in, reboot loop hell not so fine.

While it was up and barely responsive I noticed that there was a message about an operation being performed on the SD card, so I pulled it out and restarted. Droid worked just fine without the SD Card — no lag, all the apps were there, no crashes/reboots, etc.

Put the SD card back in, original problems happen. Phone is completely unusable.

Ok, I figure I’ll just back up the SD card and format it then use it again in my Droid. I removed the SD card and mounted it on my Mac in a USB adapter, drug the folder over, then watched as the number of files that needed to be copied slowly crept into the 10s of thousands.

Which, as you might guess, ain’t right.

After a little exploring, I discovered that /DCIM/Camera contained a directory /DCIM/Camera/Camera which had the exact same files as /DCIM/Camera. Including a subdirectory named “Camera”. Turtles all the way down means the SD card check probably was consuming all ram/cpu on the Droid and causing the crash/reboot.

Luckily the fix is simple — copy everything *except* the Camera sub directory to another file system, delete /DCIM, and re-use the card.

That being said, it’s 2010, why do we still have trivial inode errors in *nix filesystems? (I’m looking at you, Rubin. Seriously, wtf?)

FINALLY made it to a HackPGH member’s meeting. It’s a nice little space, not in the best part of town, but at least there’s parking and the like. Many members have donated time and equipment to help set up the space, now they’re needing help with things like putting in A/C wiring and continuing to build out the space.

So what sort of things to people do at hacker spaces? Well, whatever the members think would be a fun project. Say, for example, building and launching a high-altitude balloon or learning about fizzy drinks.

If you’re in Pittsburgh, and you’re looking for a studio space to hack on technology or take classes, haul yourself out to the next Hack PGH open house night or take a class, you won’t be sorry.

I’ve been really focused on the paying work (which is all NDA), so I haven’t much to post lately.

However, this is kinda cool, my Makerbeam kit finally showed up:

..and I’m already using it to make temporary brackets for stepper motors:

In the middle of dealing with the permit process to build a deck off of our house, I read about the little oopsie Google had with collecting network data while running Street View.

It took me less than one minute to come up with some great ways to “monetize” Google Street View data by selling it to:

• local government code-enforcement units so they can issue fines for building without a permit
• repair/building contractors buying images of “all houses with old gutters” or “all houses with peeling paint”
• law enforcement agencies looking for pot growers (cf. electric bills triggering search warrants)
• security consultants / network security software firms selling fixes for things like unpatched software or open networks

You now have one minute to come up with other ideas, GO!

Building the Makerbot Cupcake was pretty straightforward and it’s been a lot of fun playing with it. My biggest problem right now is the print envelope — 80mmx80mm is all you can realistically hope for, and that’s with a heated platform to control warpage. I’ve made some useful bits for my bike computer project and cranked out a bunch of new year’s ornaments, but other than that I haven’t been using it much. Everything I want to print is too big, either in terms of warpage or in terms of x/y size.

Since I’m interested in bigger things, so I’m looking into building bigger printers. (Anyone who wants to buy me a Stratasys can ask and I’ll give them the delivery address…) One option is to build a Mendel which has an envelope of 200mmx200mm. Another is to figure out how to put a print head on something really big, like a knee mill or a large CNC plasma table.

More platforms back in the store and I dropped the price by $10. Now you have an option of a plate with no peripheral holes as well as an option for the nicrhome kit.

Here’s how I set it up: using Kapton tape, I attached a loop of nichrome wire to the underside of the platform. I also put the thermistor in an “average” spot away from the wire:

This connects using the A6 pin on the extruder, same as other boards, all of which are basically doing what Eberhard documented on his blog. For software, you’ll need to download and build the latest ReplicatorG and firmware from the makerbot github.

Technorati Tags: makerbot

I pretty much agree with the entire daring fireball writeup except for one bit:

Admittedly, it would be very hard to get someone on the phone at Apple who would know what a device such as this one is. Apple, like most large companies, deliberately makes it difficult for consumers to reach (non-retail) employees. There is no lost prototype hotline.

True, there’s no “lost prototype hotline”, but it’s pretty easy to get ahold of Apple. I bet any one of these would have worked just fine:

• Walk into any Apple store and ask the manager how to get a lost prototype back to Cupertino.
• Post to twitter: “Hey Apple, I think I found a lost prototype. How do I return it to Cupertino?”
• Go to Apple’s website, click on the “Contact Us” link, scroll down to “Apple Public Relations”, dial the toll-free number and explain what you found.

It’s not rocket surgery, people.

Today I got an interesting screen on twitter:

Now stop for a second and think about this. Twitter won’t reveal my phone number, but they will let people search for me by my phone number.

So if I just search for all permutations of phone numbers for a given NPA (area code) and NXX (the first three digits of a phone number in the USA), I can make a list of twitter users in a given geographic area or at a specific business. NPA is often a geographically large area, but a given NPA/NXX pair can be very small — as small as a single company or small town.

Obviously you’d get caught trying to search for a bajillion contacts at once, but if I opened ~50 twitter accounts and added 10-20 numbers to each account per day, I could do 500-1000 lookups and cover a given NPA/NXX pair within a week or so.

Before you assemble your extruder, check to see how big the thermistor head is. If it’s around 1mm and not around 3mm, then you might want to use a different set of values in the thermistor lookup table, as the resistance is different at various temperatures.

The reason this matters is that it’s how the Cupcake monitors the temperature of the extruder. You want to be printing ABS at around 220C, but the smaller thermistor will “read low”, so the temperature reported back to the software is off. To get to the right temp, you have to fudge it and set it at 240, then make sure you change it to 240 anywhere in g code generated by software.

It’s easier, in my opinion, to just make/use a new ThermistorTable.cpp:

1. if you have access to a temperature probe that’s good up to around 260C, use the reprap thermistor page as a guide to making your own table.
2. follow the makerbot wiki instructions on upgrading your firmware to verify that the default software will build/install. If anything goes wrong, or this table doesn’t work for you, you need to be able to revert.
3. make a backup of the ThermistorTable.cpp file
4. copy the new table (found below) into ThermistorTable.cpp
5. rebuild and install just like you did with the default software

This is the table I’m using with a 1mm thermistor, I’m able to set the temp to 220C and print quite nicely.

#include "ThermistorTable.h"
// Thermistor
 lookup table for RepRap Temperature Sensor Boards (http://make.rrrf.org/ts)
// Made with createTemperatureLookup.py (http://svn.reprap.org/trunk/reprap/firmware/Arduino/utilities/createTemperatureLookup.py)
// ./createTemperatureLookup.py --r0=93700 --t0=24 --r1=0 --r2=4700 --beta=4881 --max-adc=1023
// r0: 93700
// t0: 24
// r1: 0
// r2: 4700
// beta: 4881
// max adc: 1023
#define NUMTEMPS 20
short temptable[NUMTEMPS][2] = {
   {1, 477},
   {54, 189},
   {107, 159},
   {160, 142},
   {213, 130},
   {266, 120},
   {319, 112},
   {372, 106},
   {425, 99},
   {478, 93},
   {531, 88},
   {584, 82},
   {637, 77},
   {690, 71},
   {743, 65},
   {796, 59},
   {849, 51},
   {902, 43},
   {955, 30},
   {1008, 4}
};

New in the store: a nichrome kit option for heating the Al print platform and international shipping options.

Here’s how I set it up: using Kapton tape, I attached a loop of nichrome wire to the underside of the platform. I also put the thermistor in an “average” spot away from the wire:

The big problem here is that the harness is not attached, so there’s no strain relief for where the wires are soldered to the thermistor and nichrome. Industrial hot glue doesn’t work, so I’m going to give heat-resistant epoxy a try next.

EDIT: Oops, completely forgot about how to hook it up! I’m using the A6 pin on the extruder, basically copying what Eberhard documented on his blog. For software, you’ll need to download and build the latest ReplicatorG and firmware from the makerbot github.

Technorati Tags: makerbot